U AD-A281 057' US Amny Corps of Engineers "Water s S p1 or C IIIIIIII IIICeII

Instituse for Water Resources

GUIDEBOOK FOR RISK

PERCEPTON AND COMMUNICATION IN

WATER RESOURCES PLANNING

Part I

- Underpinnings and Planning Applications -

__-- 4.T--

October 1993 IWR Report 93-R-13
DEPARTMENT OF THE ARMY

CORPS O ENGEERS, WATIR RESOURCES SUPPORT CENTER

INSTITUTE FOR WATER AS$OURCS Q W ?"Ih77 TELEGRAPH ROAD

ALEXANDRIA. VA 2231•-•it

RIPL TOJune 24, 1994

CEWRC-IWR

MEMORANDUM FOR COMMANDER, Defense Technical Information Center,

Cameron Station, Alexandria, VA 22314

SUBJECT: Transmittal of IWR Report 93-R-13

1. Reference AR 70-31.

2. Two copies of IWR Report 93-R-13, "Guidebook for Risk

Perception and Communication in Water Resources Planning:

Part I - Underpinnings and Planning Applications", has hereby

been Submitted

3. Initial distribution of this report has been made to

appropriate Corps of Engineers agencies. It is recommended that

copies of this report be forwarded to the National Technical

Information Center.

4. Request for the DTIC Form 50 (Incl 2) be completed and

returned to WRSC-IWR.

FOR THE DIRECTOR:

Enclosure Kyle E. Schilling

Director
Guidebook for Risk Perception and

Communication in Water

Resources Planning

Part I - Underpinnings and Planning Applications

A Report Submitted to the

U.S. Army Corps qf Engineers

Institute for Water Resources

Casey •ld&g

Fort Belvoir, Vlgnia 22060

by

Clifford Ruzsel

for

Planning and Management Consultants, Lid

RP 9 Box 15 (Hwy 515)

PO. Box 1316

Carbondale, Iinois 62903

(618) 549-2832

under

Contract No. DACW72-89-D-0020

MTC QUAMrY "IF P

October 1993

IWR Report 93-R-13

I IH 94-20430 |HIEEIEiIKII,.'• 94 9 7 ' 5 083
Y4eface

This report is a product of the U.S. Army Corps of Engineers' Risk Analysis for Water Resources

Investments Research Program managed by the Institute for Water Resources which is a unit of

the Water Resources Support Center. The report was prepared to fulfill part of several work

units in the research program. These work units focused on developing and applying the

concepts of risk preference and risk communication to water resources issues. The report

conforms to the basic planning model and to the risk and uncertainty analysis recommendations presented in "Economic and Environmental Principles and Guidelines for Water Related

Land Resources Implementation Studies" (P&G).

The risk analysis framework encompasses the four basic steps in dealing with any risk: characterization, qualification, evaluation, and management. The purpose of conducting these

analyses is to provide additional information to both Federal and non-Federal partners on the

engineering and economic performance of alternative investments that address water resources

problems. The goal is to produce better informed decisions and to foster the development of

the idea of rational joint consent by all parties to an investment decision.

The guidebook consists of six chapters, a bibliography, and appendices. The chapters provide

an overview of the terminology and concepts of risk, risk perception, and risk communication

with the public as applied to water resources. It introduces the planner to a methodology to

solving water resources planning problems that explicitly includes both risk and uncertainty

and public involvement.

This report was prepared by Planning and Management Consultants, Ltd. under terms of a

contract with the U.S. Army Corps of Engineers Institute for Water Resources. Dr. Eugene Z. -066s8100 •

Stakhiv was the initial contract manager and was succeeded by Dr. David A. Moser of the ' I$ GPM "j

Technical Analysis and Research Division. The Chief of the Technical Analysis and Research MDU 28 In

Division is Mr. Michael R. Krouse and the Director of IWR is Mr. Kyle Schilling. Mr. Robert thmDoml

Daniel, Chief Economics and Social Analysis Branch, Planning Division, Mr. Early Eiker, Chief,

Hydrology and Hydraulics Branch, Engineering Division, and Mr. James Crews, HQUSACE,

served as technical monitors for the research program. Numerous field reviewers provided Die ,tbut;"y

valuable insights and suggestions to improve early drafts. Aval1.abilit, Oode

hat SanLa./

Distm

.r1e
cQknowledgements

The guidebook evolved from the contributions of several prominent researchers in risk perception, behavior, and communication. Professor John Sims of Illinois Benedictine College, and

Dr. Kurt Alley, private practitioner, prepared papers on the effects of risk communication

problems and prospects and on the effects of personality on risk perception and decision

making. Professor Ann Fisher of Pennsylvania State University provided her perspective on

risk communication based on her experiences with several federal agencies. A discussion of the

effects of socio-cultural factors on risk perception and behavior in the face of risk was contributed by Professor Ortwin Renn of Clark University. Additional meaningful criticism and

contextual examples of risk communication were provided by Drs. Duane Baumann,John

Langowski, Jerzy Kocik, and Kevin O'Grady of Planning and Management Consultants, Ltd.

A special note of deep gratitude is extended to Edward Pettit, Donald Hayes, and Judith

McFarlin for their administrative assistance and office support.

V
Table of Contents

PREFACE ....................................................................................................................... iii

ACKNOW LEDGEM ENTS ................................................................................................. v

LIST OF FIGURES .......................................................................................................... 2

LIST OF TABLES .................................................................................................. xiii

EXECUTIVE SUM M ARY ............................................................................................ xv

I. INTRODUCTION TO THE GUIDEBOOK .................................................................... 1

INTRODUCTION .................................................................................................... 1

Purpose of This Guidebook .............................................................................. 2

Scope of This Guidebook ................................................................................ 3

Corps Planning Process .................................................................................... 4

Handling Risk and Uncertainty in Planning ...................................................... 5

ORGANIZATION ................................................................................................. 6

II. DEALING WITH RISK: THE NORMATIVE MODEL AND SOME LIMITATIONS ......... 7

RATIONAL MODELS FOR DEALING WITH RISK ................................................. 8

NOT-SO-RATIONAL MODELS: WHY DO WE CARE? ......................................... 12

NOT-SO-RATIONAL MODELS: PROBLEMS FOR PUBLIC AGENCIES ................. 14

SOURCES OF TENSION BETWEEN EXPERTS AND PUBLIC IN RISK ANALYSIS ..... 17

III. FILTERS FOR RISK INFORM ATION ..................................................................... 23

INITIAL FILTERS ............................................................................................... 23

Attention ...................................................................................................... 24

M otivation and Ability .................................................................................. 24

M edium and Form at ..................................................................................... 25

EM OTIONAL FILTERS ....................................................................................... 25

Denial and Passivity ....................................................................................... 25

"Perish the Thought--Denial of Unwanted Thoughts ................................ 25

"What, Me Worry?"--Denial of Unwanted Feelings .................................. 26

The M yth of Personal Im m unity ............................................................... 26

Inner Peace as False Security ................................................................... 26

The Spectacle Response ........................................................................... 27

Passivity in the Face of Threat .................................................................. 27

The Tendency to Remain in Familiar Surroundings Despite

Danger ................................................................................................... 28

vii
Table of Contents (continued)

Counteracting Feelings of Abandonment ............................................ 28

Mastery through Observation ........................................................... 28

Mastery through Repetition .............................................................. 28

Reaction to Authority .................................................................................... 29

"Why Hast Thou Forsaken Me?!-Feelings of Abandonment ..................... 29

Authorities as Scapegoat ......................................................................... 29

"Try and Make Me"-Rebelliousness against Mandated Measures ............... 30

Reliance on the Protection of Superior Authorities ..................................... 30

Partial Compliance: Pacifying by Concession ............................................. 30

Pleasing Authorities Rather Than Coping with the Threat ........................... 30

COGNITIVE FILTERS ........................................................................................ 31

MIXED FILTERS ................................................................................................. 32

Responding to Auxiliary Characteristics in Judging Risks .................................. 32

Resolving Cognitive Dissonance ..................................................................... 33

Response to "Framing" of the Risk .................................................................. 33

CONCLUSIONS .................................................................................................. 34

IV. COGNITIVE PROBLEMS WITH RISKY DECISIONS ............................................. 35

PROBLEMS WITH PROBABILITIES ..................................................................... 35

Understanding Independence of Events .......................................................... 36

Incorporating New Information ..................................................................... 36

Estimating Subjective Probabilities ................................................................. 37

The Dominance of Sensational Information ..................................................... 38

The Role of Expert Judgments ....................................................................... 39

PROBLEMS WITH WEIGHTING OUTCOMES IN UNCERTAIN SITUATIONS ......... 39

Utility Functions ........................................................................................... 39

Evidence about Utility Functions ................................................................... 41

PROBLEMS WITH OBSERVED JUDGMENTS IN RISKY SITUATIONS .................. 41

The Allais Paradox ......................................................................................... 42

Preference Reversal ......................................................................................... 43

Estimates of Relative Riskiness ....................................................................... 45

CONCLUSIONS .................................................................................................. 48

V. SOCIAL PRESSURE AND AMPLIFICATION .......................................................... 49

GENERAL CULTURAL BACKGROUND .............................................................. 50

CULTURAL GROUP AFFILIATIONS ................................................................... 51

RISK IN THE POLITICAL ARENA ....................................................................... 52

SOCIAL AMPLIFICATION OF RISK .................................................................... 53

CONCLUSIONS .................................................................................................. 54

0__
Tabl of Contents (continued)

VI. GUIDELINES FOR RISK COMMUNICATION ........................................................... 55

FRAM EW O RK ................................................................................................... 55

GENERAL GUIDELINES ON RISK COMMUNICATION CONTENT ..................... 57

When Understanding Is the Objective ............................................................ 57

Perceiving Natural Processes and Probabilities ........................................... 57

Acknowledging Differences in Expert Opinion ........................................... 59

Framing the Outcomes from Alternative Projects or Policies ....................... 60

Understanding the Insurance Analogy ..................................................... 62

Setting the Risk in Perspective .................................................................. 63

When Action Is the Objective ......................................................................... 66

Perceived Seriousness of the Risk ............................................................. 66

Perceived Interest of the Group ................................................................ 68

Perceived Efficacy of Risk Reduction Efforts ............................................. 68

GENERAL GUIDELINES FOR RISK COMMUNICATION FORM .......................... 69

The Message Must Be Vivid and Personal ........................................................ 69

The Message Should Originate from a Person ................................................. 70

The Message Must Come from a Credible Source ............................................ 70

The Message Should Be Clearly Applicable to the Person Receiving It ................ 70

The Message Must Be Clear, Specific, Concise, and Concrete ............................. 71

Multiple Messages Should Contain a Common Theme .................................... 71

GUIDELINES FOR SEEKING RISK COMMUNICATION FEEDBACK .................... 72

When Understanding Is the Objective ................................................................. 72

When Action Is the Objective ............................................................................. 72

SU M M A RY ......................................................................................................... 73

When Understanding Is the Objective ................................................................. 73

When the Objective Is Action ......................................................................... 73

Design and Delivery ....................................................................................... 73

SUPPLEMENT OF EXAMPLES TO CHAPTER VI ........................................................ 75

EX AM PLE 1 ....................................................................................................... 75

EX AM PLE 2 ........................................................................................................ 76

EX A M PLE 3 ........................................................................................................ 77

EX AM PLE 4 4.................................................. ...................................................... 78

EX AM PLE 5 ........................................................................................................ 79

EX AM PLE 6 ........................................................................................................ 79

EX AM PLE 7 ........................................................................................................ 83

REFEREN C ES ......................................................................................................... 85

_ _ _ ix
List of Figures

11-1 Costs and Damages as Related to Project Choice and Natural Event .................... 10

11-2 Illustration of a Weighting Function for Outcomes Under Risk ........................... 13

11-3 A Schematic of Sources and Processing of Information About Risks .................... 18

IV-1 Decision Weights Related to Probabilities .......................................................... 38

IV-2 Utility Function Shapes and Their Characterization ............................................ 40

IV-3 Dart Board Patterns for the Preference Reversal Experiment ................................ 43

IV-4 Rankings of Hazards: A Few Examples ............................................................. 47

VI-1 Expected Annual Damage and Benefit Distributions ............................................ 63

VI-2 Estimated Versus Actual Ranking of Risk ........................................................... 64

S-1 Cattle Rancher Decision Tree ........................................................................... 77

xi
List Of Tables

11-1 M atrix of Payoffs (Net Benefits) ............................................................................ 8

IV -1 Payoff M atrix ..................................................................................................... 42

IV-2 Elements of a Survey of Risk Perception ........................................................ 46

VI-1 Principles and Guidelines for Risk Communication: A Schematic .................... 58

VI-2 Best and W orst Outcom es .............................................................................. 61

VI-3 Outcom e Inform ation ................................................................................... 61

VI-4 Expected Annual Damage and Benefit Distributions ........................................ 64

VI-5 Risks that Increase Chance of Death by 0.000001 ............................................ 65

VI-6 Qualitative Factors Affecting Risk Perception and Evaluation ........................... 67

S-1 Communication Themes and Examples ........................................................... 75

S-2 Cost-effectiveness of the Programs .................................................................. 76

S-3 Application of Principles of Persuasive Communication

Television Comm ercial A ........................................................................... 80

S-4 Application of Principles of Persuasive Communication

Television Com m ercial B .............................................................................. 81

S-5 Measurement of the Effects of the Drought ...................................................... 82

XUl__x
a Execuhtve Summary

The purpose of this guidebook is to provide Chapter IV discusses what is known about

observations and theories about how people human cognitive operations in uncertain

perceive risk and to set out guidelines that situations.

will assist water resource planners and

managers in their efforts to communicate with Chapter V deals with the effects of social

the public and with decision makers about pressure on risk perceptions and the potential

situations in which risk is important. for social amplification of risk perceptions.

Elements of risk and uncertainty are found in

all areas of water resource planning and Chapter VI is the heart of this manual. It

management. Different techniques for provides guidelines for risk communication

characterizing risk as well as different meth- that represent the lessons to be drawn from

ods for identifying desirable strategies for the problems discussed in the previous

dealing with risk are found in different areas chapters. Two situations are distinguished.

(flood control, navigation, drought, environ- In the first, public understanding of a promental management). gram or project is what is at stake. In the

second, the Corps decision makers believe

The guidebook consists of six chapters, a that there is a need for public action, espebibliography, and appendices. It develops a cially action in response to some natural

picture of what is known about the public's hazard. The following pages of this summary

perceptions and reactions to risk and the best will focus on Chapter VI.

policies and methods of communication with

the public about risk. An extensive bibliogra- Guidelines for Risk

phy is provided under separate cover for Comlunicatfio

those wishing further information on these

topics (Part II -An Annotated Bibliography). There are four elements of the risk communication process that need to be considered by

Chapter II discusses models of risk behavior, the planner:

It establishes the foundation for risk analysis

and management and discusses the problems • Objective(s): Why is the communication

that interfere with straightforward application being undertaken?

of this foundation.

• Content of the message: What information is

Chapter III deals in more detail with the to be conveyed in order to accomplish the

methods people use to filter information objectives?

pertaining to risk situations. This chapter ties

directly to the public's perceptions of, and * Form of communication: How should the

reactions to, risk, and the role of precognitive, message be transmitted from the source to

emotional response is emphasized. the receiver?

xv
• Feedback from the audience: What is being - Stress the analogy of the project to an

received? insurance policy against catastrophic loss

whenever this is appropriate.

Two broad alternative objectives are (1) the

planner may want to provide the audience • Provide information that allows the audiwith a better understanding of the risk and ence to assess the risk (at least in terms of

uncertainty surrounding planning alternatives threats to life and limb) of the contemplated

and thus to stimulate cogent and informed project or program relative to other actividiscussion-and ultimately a defensible ties and programs, both individual and

resolution; or (2) the planner may desire to collective.

communicate risk in order to encourage

appropriate behavior by individuals and While the principles developed above for the

communities. Message content and audience content of risk communication attempt to

feedback will vary depending on the objec- anticipate and deal with specific problems,

tive. The form of the communication is less success can by no means be guaranteed.

dependent upon the objectives. Accordingly, it is well to check on the

progress (or lack of it) being made. The

When Understanding Is the Objecive following is a minimal checklist.

The guiding principles, which pertain to the

content of the risk information program, can Check for the audience's interpretation of

be summarized as follows, probabilities in the case at hand. This may

involve pretesting physical analogy models

Uncertainty should be expressed in a for definitional fitness (e.g., the wheel of

variety of ways using such physical analo- fortune). Another question is whether the

gies as wheels of fortune and jars containing notion of independence is getting across or

colored balls. Care should be taken to use requires reinforcement. A third general

language and mechanisms that do not problem area to be explored is the possibilencourage thinking of independent events ity that the audience contains a significant

as cyclic, with fixed return intervals. (The number of people who subscribe to some

common expression, "100-year flood," may sort of causal or ethical theory of the events

be counterproductive.) in question that interferes with their ability

to think of them as random.

- Disagreements among experts should be

made explicit and not concealed. If Check for the presence of patterns of utility

possible, the range of opinions should have weights that would point toward incautious

probability weights attached to the alterna- policy prescriptions. Perhaps the largest

tive possibilities, concern here is the possibility of risk

seeking when all options will lead to losses.

* The decision problem outcomes should be

i,amed in at least two ways, one stated as Check for the possibility of internal confulosses from best case and one as gains from sion such as that evidenced by the preferworst case. ence reversal phenomenon. This will xv'
probably involve asking preference ques- All members of the community should be

tions two ways: one using strictly prefer- required to make sincere efforts to reduce

ence terminology; the other using the the risk.

willingness-to-pay format developed in the

contingent valuation literature. ° The specific strategies of Ehe campaign

should rely, to the extent possible, on

When the Objective Is Action providing feedback on risk reduction efforts

With this objective we have somewhat more and providing economic and social incenexperience, primarily because the effects of tives for doing so.

weather-related hazards are often mitigated

through voluntary action by citizens; the With respect to gleaning feedback on the key

campaigns that call forth that volunteering issues, the following four items are particuhave been studied and refined over the years. larly crucial.

Examples of events that are conducive to the

voluntary actions of citizens include shoring - Check to make sure that the actions being

up a levee with sandbags to prevent flooding touted in the campaign are perceived as

and a door-to-door campaign to warn people effective in mitigating the threat.

of approaching or impending danger such as

a flood, brush fire, or hurricane. The guiding o Check that the audience sees the goal of the

principles which pertain to content can be campaign and the manner of its application

summarized as follows, and enforcement as fair and effective (e.g.,

one group, neighborhood, or town is not

" The campaign should effectively convey a seen as carrying the load for others).

message about the seriousness of the risk.

This effort should not, however, be allowed • Check that the seriousness of the threat has

to degenerate into a scare campaign, for the not been so emphasized that significant

behavior triggered by fear is likely to be amounts of regressive behavior have begun

counterproductive, to show up.

" The program should provide social rein- Note that time constraints may not allow

forcement of risk reduction behavior gathering feedback during an event; ex post

especially at the local level. This will research may be required.

cultivate strong group interest and moral

commitments within the community. The Form of Risk Communication

Past research and theories of persuasive

" The campaign should make an attempt to communication suggest several important

convince the consumers that their actions requirements in designing maximally

aimed at reducing risk will help to mitigate effective messages, whether the objective is to

risk impacts. induce understanding or action.

"• Risk reduction efforts requested by * Messages should be vivid, that is, evoking

the campaign should be equitable. lifelike images within the mind.

x Vii
Messages should come from a credible • The message should be clearly applicable to

source. Information from authoritative the person receiving it. This requires that

sources is more likely to be believed and, information should be "personalized" or

therefore, acted upon. It may be useful to "localized."

combine the information from various

sources even if they appear at odds over a * The means for delivering the message

particular issue (e.g., environmental groups should make the maximum use of personand chemical companies). to-person communication through local

media personalities, leaders, and citizen

The message should be clear, specific, advisory groups. Impersonal messages

concise, and concrete. Words used in a should be avoided.

message should immediately bring an

image to a person's mind. Specific but • Modeling of risk reduction behavior by

concise messages are easier to read and respected individuals in the community

understand. should be sought as the most powerful

means of persuasion.

xv0u
Introduction to the Guidebook

Introducwim dealing with necessary judgments and

decisions. It is hardly less surprising that 4t

The extent to which all human activities generations of academic and practical thinkers

proceed in a setting of uncertainty about the have turned their attention to the question:

future is captured in the old saw: "Nothing is How should we to make decisions in the face

certain but death and taxes." But like all such of uncertainty? Finally, it may surprise a few

saws, this one could do with some straighten- readers, but not many, to learn that the

ing and sharpening, for while all humans are answers suggested for this last question do not

destined to die, none of us can know the time always match the ad hoc procedures generor manner of our passing. More important, ated by individuals as part of the business of

we can never even be sure that efforts we getting by.

make to affect the certain event are doing the

slightest good. And where taxes are con- The method chosen for coping with uncercerned, it is impossible to predict year-to- tainty in many planning and policy-making

year changes in the key rules that influence contexts is simple if not very defensible: those

how we seek income, how we spend it, involved pretend it does not exist. They plan,

how we save and invest, and even how we decide, and speak publicly as though their

keep records. point estimates of the future would certainly

come about. Think, for example, of discusBeyond the supposed certainties of death and sions of the federal budget deficit. How often

taxes, every part of our lives involves us in do these explicitly recognize the tremendous

decisions in the face of an uncertain future. uncertainty with which the projection of

Every decision may produce any one of a government revenues and expenditures (and

number of results depending on what nature hence their difference) is laced?

does (floods, droughts, hail); what other

people do (decide to buy stocks, to go to the While this approach surely hampers us in

same movie at the same time and theater, to such fields as fiscal and health-care policy, we

drive drunk); and even what our own bodies appear to be able to live with the performance

do (cramp up in cold water, turn out to be penalty in return for the rhetorical simplicity.

allergic to an exotic new food). But when our policies impinge on nature and

on the relationship among human actions,

Given that we are uncertain about so much, it nature's responses, and the feedback from

is not surprising that people have developed nature to human health and well-being, we

idiosyncratic rules of thumb-including rules do recognize the need to explicitly take

that deny the existence of uncertainty-for uncertainty into account. Thus, we require
that dams, bridges, and culverts be designed manual has been designed to set out these

and built with some specified small-probabil- problems in the context of the normative

ity rainfall events in mind. (At the other tail model for dealing with risk in decision

of that event scale, we plan reservoirs and making; to identify which problems may

emergency water supply facilities to protect us usefully be thought of as communication

against lack of rainfall out to some chosen problems; and to suggest strategies and

level of event rarity.) We set ambient envi- techniques for avoiding those that are avoidronmental quality standards in terms that able or ameliorating those that cannot be

recognize that in some rare combinations of avoided.

natural conditions they cannot be met at

acceptable cost. Our regulations regarding Purpose of This Guidebook

sites containing improperly disposed-of toxic The purpose of this guidebook is to provide

compounds also use probability-type state- observations and theories about how people

ments (expected cancer cases per year in the perceive risk and to set out guidelines that

local populations) in specifying the standards will assist water resource planners and

for cleanups, managers in their efforts to communicate with

the public and with decision makers about

In no field of public policy, planning, and situations in which risk is important. Elemanagement are the techniques for analyzing ments of risk and uncertainty are found in all

uncertainty better developed or more areas of water resource 1,1 ining and managewidely disseminated than they are for ment. Different techniques for characterizing

water resources. And in very few fields are risk as well as different methods for identifythe data required to characterize that uncer- ing desirable strategies for dealing with risk

tainty even close to being as rich in geo- are found in different areas. For example,

graphical coverage, time periods covered, standard flood damage analysis may be

and events measured. conducted using historical data on rainfall and

streamflows in conjunction with knowledge

On the other hand, roughly in parallel with of floodplain configurations and the nature of

our developing technical knowledge and skill, activities located in the floodplains. But, the

a realization has grown that there are often extraordinary situation that would be created

large and troublesome gaps between our by dam failure does not lend itself to the same

expert calculations and the perceptions and methods because historical data on actual

rules of thumb of the lay public. This is failures is insufficient to produce useful

troublesome because misperceptions and probability estimates for specific dams and

misleading rules of thumb can constrain specific situations. Modes of failure must be

society from opportunities for social gain. analyzed in terms of individual contributing

events and their probabilities. These probThere appear to be several different sorts of abilities will often be based on the profesproblems behind these gaps. Some seem to sional judgment of experts in dam engineerbe more susceptible to solution through ing The final analysis strings together these

careful communication between the planners contributing events with assumptions about

and experts and the public; some less. This their independence (or, in some cases, their 2 ______
correlations) to arrive at an overall probability guidance. The Corps has held a series of

of failure. Estimating the consequences of workshops and training courses since 1987,

failure for the downstream communities will that focus on how risk analysis can be useful

also require different techniques than will in developing pertinent information for

ordinary floods because of the nature of the planning and decision making. In the area of

flow resulting from dam failure, research, the Corps has produced or supported several documents and reports

Analogous contrasts can be made for naviga- including: Risk-Based Decision-Making in

tion risks (where we may only imperfectly Water Resources (Stakhiv and Haimes 1986;

understand how obstructions are created, Haimes and Stakhiv 1990; Stakhiv, Moser,

though we usually have good historical data and Haimes 1992), which provide a crosson water levels and flows in rivers); drought section of risk analysis applications to various The purps c

(where predictions of weather over future types of water resource problems; an Engiweeks and months is key to management neering Circular (EC) entitled Risk Analysis in guidebook is to,

decisions, though we may lack forecasting Planning; and Facing Natural Hazards: Uncer- observations and

skill extending beyond 3 or 4 days); and tain and Intertemporal Elements of Choosing theories about how

environmental management (where ecologi- Shore Protection Along the Great Lakes people perceive risk

cal-modeling capability may reflect substantial (O'Grady 1992). The Army Corps of Engi- and to set out

ignorance of how relevant systems, such as neers has also developed several methods for guidelines that will

wetlands, actually function in the larger assessing risk and uncertainty in various areas assist water resource

context as well as a serious lack of historical of water resources planning (Holliday 1987, p n and managers

data on inputs and end points). Section 1). inters to

in their efforts to

Other uncertainties such as political, Despite, or because of, these advances in the communicate with the

institutional, and economic factors are area of risk and uncertainty for water re- public and with

even more difficult to explicitly incorporate, sources planning, the need for a manual decision makers about

These factors are often influenced by the regarding risk perception and communication situations in which risk

ability of state, local, and private entities to remains. Both the decision maker's and the is important.

cooperate in the implementation of structural public's perceptions of risk from natural and

and non-structural measures (Hobbs 1987, man-made influences must inform the

Section 7). assessment of risk and uncertainty in the

project planning process. In order to underNoting the importance of risk in water stand risk behavior, one must understand risk

resource planning and management (and the perception and how it may influence the use

requirements in Economic and Environmental of technologies designed to reduce or control

Principles and Guidelines for Water and Related natural hazards.

Land Resources Implementation Studies (U.S.

Water Resources Council 1983), hereinafter Scope of This Guidebook

referred to as Principles and Guidelines or All perspectives on risk, including the percepsimply as P&G, the Army Corps of Engineers tions of individuals, the public, as well as

has developed a program to address risk planners and decision makers, affect how risk

including training, research, and field is managed. This study begins with four

_________3
concerns involving perceptions and behavior outlining an orderly and systematic technique

under risk and uncertainty. The four con- for project evaluations. Its six primary

cerns are: steps are:

"The individual's and public's concept- • Specification of problems and opportunities

ualization or perceptions of risk, its measurement, display, and relevance to water • Inventory, forecast, and analysis of conditions

resources analysis

- Formulation of alternative plans

" The public's exhibited behavior under risk

as measured by appropriate instruments - Evaluation of effects

and its relevance to water resources

* Comparison of alternative plans

" Decision makers' attitudes toward and

perceptions of risk given the typical choices • Plan selection

and risk-cost trade-offs that are made in

water resources These six steps each include efforts to cope with

risk by understanding the information relevant

" The differences in public attitudes regarding to the risk involved. The information pertinent

comparative risk assessment among natural to a project must be evaluated and understood

hazards and between the technologies in terms of its accuracy, relevance, and dependdesigned to lessen the threats ability. The Corps aims at achieving increases

in national economic efficiency but realizes that

Just as risk perceptions of individuals, the both its information about the past and its

public, and decision makers may vary across projections of the future will always involve

particular natural or man-made hazards, uncertainty.

effective methods of risk communication

likewise may vary according to particular Therefore, this process places special emphasis

water resource-related projects. on informing and educating decision makers in

the Corps and in federal, state, and local

Various water resource projects and the four authorities, so they can fully evaluate the factors

concerns about perception will be considered that weigh in the decision-making process.

in relation to each other and depicted through These relevant factors, as outlined in the

the six steps of the planning process. The six companion guidebook to this manualsteps are important to consider, since assess- Guidelines for Risk and Uncertainty Analysis in

ments of risk may be influenced by the Water Resources Planning (Greeley-Polhemus

passage of time and the implementation of Group, Inc. 1992), are the (1) basic assumpeach of the steps of the planning process. tions employed, (2) data and information

analyzed, (3) unavailable data and information,

Corps Planning Pcoess (4) areas and degree of risk and uncertainty

The planning process of the Corps is a formal involved, (5) reasoning and rationale used in

method of evaluation and decision making, formulation, evaluation, and selection. 4
Handling Risk and Uncrtanty in Planning * The planner should carefully select the

Let us begin by observing that it used to be variables that will be used in determining

common for "risk" and "uncertainty" to mean measurement error and sources of risk.

different things. Knight (1921) introduced

the distinction between a situation involving * Standard methods of risk evaluation may be

risk, in which probabilities over the possible used when risk can be characterized by a

outcomes were known, and a situation probability distribution that is based on

involving uncertainty, in which they were not. firm data, such as hydrologic risk.

Commonly, though by no means universally,

today this distinction has disappeared be- - The planner should explain why certain

cause, as we shall see, the notion of probabil- aspects of a project have been selected as

ity has been broadened to include subjective areas of risk. The heart of the

likelihood judgments as long as these are • Possible alternative outcomes should be

made in such a way as to conform to the rules developed utilizing sensitivity analysis (the inoividuals thatmthe

for probabilities. process of changing assumptions then individuals who make

comparing the various outcomes). up this "public" neither

Nonetheless, Section 1.4.13 of the Principles perceive, nor respond,

and Guidelines outlines the requirements for Subjective probability estimates may be to risks in terms

planners regarding the assessment of risk and useful in determining a spectrum of consistent with any

uncertainty in the planning process. The outcomes, but the report must clearly narrow concept of

P&G defines risk as situations in "which the identify these estimates as subjective. rationality.

potential outcomes can be described in

reasonably well-known probability distribu- Utility functions and public perceptions (if

tions, such as the probability of particular well known) may be used to suggest the

flood events" (p. 5). Planners are required to best alternative design to decision makers.

examine, then determine, the level of uncer- (P&G, pp. 15-6)

tainty in the data or the assumptions regarding "future economic, demographic, social, While this information is helpful, it does not

attitudinal, environmental, and technological provide full application guidelines for plantrends." ners who have to characterize and evaluate

risk during project development. In particuThe P&G also provides the following recom- lar, it does not help in coming to grips with

mendations regarding the application and differences in risk perception between the

handling of risk and uncertainty: public and the planners or with techniques

for communicating with the public about risk.

"* When working with related projects, the The heart of the problem-and the heart of

planner should attempt to use the same the rationale for this guidebook-is that the

analyses and presumed probability distribu- individuals who make up this "public" neither

tions. perceive, nor respond, to risks in terms

consistent with any narrow concept of

"* Techniques utilized in determining risk rationality. In some situations, it appears that

should relate to the stage of planning. prerational or childlike responses are chosen;

5
while in others, so many facets of the risk are Chapter III deals in more detail with the

taken into account in making judgments that methods people use to filter information

we might almost be tempted to call the pertaining to risk situations. This chapter ties

behavior "super-rational." But only rarely directly to the public's perceptions of, and

will individuals easily and quickly buy into reactions to, risk, and the role of precognitive,

the models for coping with risk that we refer emotional response is emphasized.

to as "normative." (These models are briefly

reviewed in Chapter H1.) Chapter IV discusses what is kncwn about

human cognitive operations in uncertain

O mgauiation situations.

This manual consists of six chapters, a Chapter V deals with the effects of social

bibliography, and appendices. It develops a pressure on risk perceptions and the potential

picture of what is known about the public's for social amplification of risk perceptions.

perceptions and reactions to risk and the

best policies and methods of communication Chapter VI is the heart of this manual. It

with the public about risk. An extensive provides guidelines for risk communication

bibliography is provided (under separate that represent the lessons to be drawn from

cover) for those wishing further information the problems discussed in the previous

on these topics (Part II -An Annotated chapters. Two objectives are distinguished.

Bibliography). First, the objective of the planner is to provide

the audience with a better understanding of

Chapter II discusses models of risk behavior, the risk and uncertainty sur-rounding

It establishes the foundation for risk analysis planning alternatives. Second, the objective

and management and discusses the problems of the planner is to encourage appropriate

that interfere with straightforward application behavior by individuals and communities,

of this foundation. especially in response to natural disaster.

6 _____
Dealing with Risk: The Normative

Model and Some limit aons

This chapter will begin with a brief review of observed, and in this guidebook we shall feel

normative (or, as they are sometimes called, free to use the two words interchangeably.

"rational") models for decision making in However, a potentially greater problem for us

conditions of risk and uncertainty. We and for users of this book, because it is often

assume that our audience has at least a hard to detect, is variation in the meaning of

nodding acquaintance with these methods. the work "risk" itself. For example, when we

From that foundation we shall move on to speak of "risk aversion" and "risk seeking" as

examine the tensions between this benchmark descriptions of preferences, we shall not be

and the most common perceptual and opera- referring to a dislike of uncertainty per se, but

tional approaches exhibited by the public at rather to a feeling related to the dispersion of

large. These tensions may be thought of as outcomes and the changing value of the

arising from three broad classes of influence: marginal unit of gain or loss across the range

of outcomes. Often in the technical literature,

" Problems created by our ways of approach- however, "risk" means something even more

ing life generally (emotional problems) and specific. Sometimes it means the probability

the results of our response to actual experi- of contracting a disease (as in, "the cancer risk

ence with risk or to communications about of smoking is..."); sometimes it means the

risk that reach us from our friends, neigh- chance of death or some other serious health

bors, or colleagues, or from the media. damage for a randomly chosen member of a

popu'ation from a cause or activity (as in, "the

" Limitations on our ability to think as the risk from superfund site x is 10-5"); somedetached experts say we should ("cognitive" times it means the number of deaths per year

problems for short) from a cause or activity; and somctirmes it

means a complex amalgam of characteristics

" The conditions in which we find ourselves with no one measurement scale that characwhen called upon to make such decisions terizes an activity-its riskiness-as perceived

("contextual" or "exogenous" problems) by lay people. The best we can do is to try to

be clear about the particular meaning we are

Before we proceed, let us return very briefly to attaching to risk in particular parts of the

matters of terminology. We have already discussion. But the reader must be alert for

observed that the old distinction between risk variations in the meaning of risk in other

and uncertainty is no longer generally sources of information.

7
Rational Modelsfor Dealing We may also know what the probabilities of

With Risk nature's choices are. That is, we may know

that event 1 occurs 50 percent of the time,

Let us begin by assuming that our interest in event 2 occurs 30 percent of the time and

risk arises from the necessity of choosing event 3 occurs 20 percent of the time. Where

among alternative programs, policies or these probabilities might come from will be

projects when the outcomes that follow from discussed later. For now, we can think of

the choice are partly determined by events them as reflecting historical experience.

over which we have no control mnd that,

indeed, appear random to us. To illustrate, let The fundamental problem of choice under

us be more specific and assume that we are uncertainty may be thought of as arising

required to choose among three alternative because, in general, no project will have

projects competing for investment dollars (A, payoffs in all states that are at least as large as

B, C). Further, assume that the actual results those of any other project choice. If such a

from choosing any one of the projects depend project does exist, there is surely no point in

on which of many alternative possible "states doing other than choosing it. But in the

of nature" (1, 2 ...... n) is actually experienced. inconvenient "real" world such a trivial

Thus, these states are exogenous to our choice version of uncertain choice is rarely seen.

but, jointly with that choice, determine the Thus, in the payoff matrix (Table 11- 1), we can

net benefits accruing from it. Also assume we see that no project dominates. A is the best

have quite complete information, including choice if we are certain nature will choose

an estimate of how likely each state of nature event 1. C is the best if we know in advance

is to occur,' and estimates of the payoffs (net that event 2 will occur, and so on. But, the

benefits) that accrue when a project is chosen essence of risk is that we do not know.

and a state of nature occurs. Thus, we have at To try to make the nature of the problem a

our disposal information about what could little clearer, let us think about the design and

happen, depending on how we choose. That construction of a levee that will protect a

information might be summarized in a matrix small town from flooding. Two things are

of payoffs like that in Table 1I-1. obvious: a higher levee will cost more to

Table 11-1

Matrix of Payoffs (Net Benefits)

Nature "Chooses" a State or Event

Project 1 2 3

We A 5 4 0

choose B 2 -10 9

a project C -2 6 6

'It is not essential that either the possible states of nature or 8 _their likelihoods be independent of project choice, but it is

certainly simpler for this review.
construct; and a higher levee will offer protec- How do we decide which project to undertake

tion over a greater range of possible flood then? In brief, we have to seize on one state of

crests. If we knew in advance how high the nature or one payoff for each project, or we

crests would be during the planning horizon, have to summarize all the information we have

we could choose the "best" height. It would be into one number per project. Some alternative

the one that minimized the sum of the costs of rules:

levee and the remaining damages from

flooding. Look at the worst nature can do and pick

the project that produces the best result in

A very simple version of this problem is that situation, realizing that (a) this may be

presented in Figure Il-1, where we distinguish very unlikely, and (b) if another state,

three levee projects A, B, and C of progres- perhaps any other state, actually materialsively greater height. In Figure Il-la we show izes, we will probably regret our choice.

the costs of each levee and the damages that how high the crests

would occur in the "protected" town at various Look at the worst result for each project and would be during the

river flood crest heights. (For simplicity we pick the project that gives the least serious planning horizon, we

pretend we are interested in only one event, of these worst outcomes. Picking the could choose the "best"

what we might call the design flood for the project that gives the least serious result is height. It would be the

project.) The hypothetical damage curves very conservative and puts a limit on our one that minimized the

assume that damage is zero until the levee is losses. sum of the costs of

overtopped at which point substantial damages

are incurred immediately. As the height of the Pick the project that gives the best of the

crest rises above this level, the damages best results. This is a very aggressive damages from flooding.

increase more than linearly, and at some strategy and ignores the possibility of a truly

enormous crest height it no longer makes any horrific loss. Neither method makes any use

difference which levee was built. of the probability information we assumed

to be available.

In Figure II-lb we bring costs and damages for

the hypothetical projects together, showing Another option is to create a summary

their sum in each case. And, most impor- measure using all the available informatantly, we show that over different ranges of tion. Called the expected value, it would

crest height, different projects dominate. If we be calculated for each project. For the

knew, for example, that the maximum crest payoff matrix (Table 11-1) and the probabiliheight would be between CO and C1, we would ties set out earlier in this section, the

build levee B. But we do not know. Nature expected values of the net benefits are as

sends us no memo of intent, though we can follows:

observe nature's actions and, if we have been

doing so for many years, we can infer some- E(Project A) = .5(5) + .3(4) + .2(0) = 3.7

thing about what might happen in the future.

These inferences are the source of probability E(Project B) = .5(2) + .3(-00) + .2(9) = -0.2

information-information about the likelihood

of crests of particular heights. E(Project C) = .5(-2) + .3(6) + .2(6) = 2.0

_________9
Figure 1I-I

Costs and Damages as Related to Project Choice and Natural Event

(a) Costs and damages of three levee projects

Cost of C

Damages Damages Dage $ Cost of B withLeveeA eeBwth=e Q/

Over

Planning

Horizon* Cost of A

River crest - highest flood over planning horizon

(b) Costs plus damages for the three projects

D Damages with C

$ Cost Of C

Over

Planning Damages with A

Horizon*

Cost of B

Cost Of A

I- A is Best-.- -B is Best-,-- - C is Best

Co Cl

River crest - highest flood over planning horizon

*An added complication, ignored here, Is that we do not know when any flood will occur.

10
And by this criterion, project A is best. In this latter connection, however, it is

More generally, the expected value of important to note that this "expected value"

any project is the sum of the probability measure is not a prediction of the result that

weighted outcomes over all possible will actually be observed in any particular

states of nature; or, for continuous experiment. So that if we have a single

probability density functions, the integral decision to make, the expected values of the

over the range of possible outcomes of the alternatives are not predictions of outcomes

product of the density function and the net but simply agreed upon criterion values for

benefit function. ranking the decision alternatives. One very

easy way to understand the difference beAs we note below, this simple summary tween prediction and expected value is to

measure can be elaborated for cases in which think of rolling a fair die. We can predict

the gap between maximum losses and with certainty only that the result will be

maximum gains is so large that we might either a 1, 2, 3, 4, 5, or 6 on the top face. We the alternatives are not

want to weight losses more than gains (or can "predict," as we do in games involving predictions of outcomes

even vice versa). It is also possible to elabo- dice, that some particular face will come up, but simply agreed upon

rate on the methods that seize on one particu- but we have only one chance in six of being criterion values for

lar payoff, and indeed, we can even decide proved right in a particular trial. On the other ranking the decision

what to do by trying to anticipate how badly hand, the expected value of the operation: alternatives.

we will feel (how much we will "regret" our toss one die and record the top face is (6 + 5 +

choice) when our decision is actually stacked 4+ 3 + 2 + 1) +6= 21 +6= 3.5. This can

up against nature's choice. never be the result of any single trial of tossing

the die. But if we toss the die 1,000 times,

But to go back to the expected value criterion record the value of the top face each time, add

as representing the method of choice, we the results, and divide by 1,000, the result

observe that there are several ways to under- will be very close to 3.5.

stand what it means, any one of which may

be helpful to any particular person. If we It is very easy to construct examples in which

begin by asking how we might use all avail- agreeing to use the expected value criterion

able information, we can see that this tech- leaves us very uncomfortable. It is also

nique seems an intuitively sensible answer. possible that some readers will be utncomfortWe have weighted our information aibout the able with the notion of a probability distribupossible results using our information about tion over outcomes. Therefore, let us briefly

the relative likelihood of our experiencing any consider these two areas of discomfort.

particular result. If, on the other hand, we

think about the problem as though we could In some applications, even government

repeatedly run an experiment in which we agency applications, in which gains are not

choose and then nature chooses, and 'itially personal and bankruptcy is not a possibility,

we observed a result, the criterion just decision makers may want to put a greater

discussed can be seen as our best predictor of weight on large losses (e.g., large losses of life

the average of all the results observed in that and property in a flood) than on large gains

series of experiments. (e.g., from recreation days experienced on a 11
full flood-control reservoir). In such circum- while simple physics will not carry us very far.

stances, it is possible to introduce another (This is the origin of the old risk-uncertainty

weighting function---economists often refer to distinction.) Does it make sense even to talk

it as a utility function--that is tailored to the about, let alone to use, probabilities in such

feelings of the decision maker in question. Or cases? Many, though by no means all, of those

it may be instructive to try several different who have thought deeply about this subject

weighting functions and see how sensitive the believe that answer is yes, it does make sense

implied choice of project is to the choice of not only to talk about but also to use probfunction. A typical weighting function abilities, even when these are "subjective"-

displaying the conservative bias known as based on judgment and experience rather than

"risk aversion," is concave to the results axis- physical laws or data. In complicated cases,

that is, it increases as results increase but at a such as the dam collapse possibility, it may be

slower and slower rate?2 Such a function is necessary to break down the path to failure

not only to talk about displayed in Figure 11-2. (decompose the risk) into small steps that

but also to use different individuals can wrap their minds

probabilities, even Now, what about probabilities? It may seem around, and later, to combine many judgwhen these art to be one thing to talk about probabilities ments into an overall probability that all the

"" where coins and dice are concerned, some- failures necessary to produce a major accident

judgment... thing slightly different where local rainfall and would occur.

streamflow are the states of nature, and quite

another when we have to cope with a ques- There are also established methods for

Ution of possible massive structural failure (e.g., apdating subjective probabilities as experience

collapse of an earthen dam). In the first case, and information accumulate (Bayes' theorem.

probabilities are determined by simple For an example, see Parzen (1960) and in

physics and the shapes of the chance deter- Chapter IV.)

miners, (e.g., we ignore the infinitesimal

probability that a tossed coin will land and Not-So-Rational Models: Why Do

stay on its edge, and we argue, a priori, that We Care?

unless it has been tampered with, either side

down is equally probable.) In the second case We have tried to emphasize that the descrip-

(hydrologic), we can look at quite long tion above is fundamentally normative

historical records--at least we can in most (prescriptive)-a matter of what we ought

places in the industrial economies. Using to do when we make decisions under risk.

more or less sophisticated techniques we can There is, however, a considerable body

extract the information in that record and of evidence suggesting that individuals do

obtain estimates of the relevant process not always, or even usually, follow -his

probabilities-for example, a continuous prescription. The catalog of human failings in

probability density function for rainfall or this regard is long and will be discussed in

streamflow someplace.

SThis notion, originally called "moral expectation," was

introduced into the probability literature in the eighteenth

But in many important decision contexts we century by Daniel Bernoulli as a way of understanding why people are not willing to pay infinite amounts to play games

have either no record or a very short record, with unbounded expected values (the "St. Petersburg Paradox"). 12~
Figure 11-2

Illustration of a Weighting Function for Outcomes Under Risk

Weighting (utility) function value

Result

(e.g.: money return)

more detail in the chapters that follow. But known as the law of large numbers, where

for present purposes consider just a few items the garble involves imputing a will and a

from it. memory to the coin so that it "knows" its

record over the past ten tosses and

Many individuals have great difficulty somehow "acts7 to push the cumulative

understanding the fundamental concepts of record back toward the long-run predicted

uncertainty or randomness--especially the result of one-half heads and one-half tails.

notion of "independence" between two such

events (e.g., between the first ten tosses of a In more complex situations, such as those

coin and the eleventh). Thus, it is common created by the uncertain forces of weather,

for people to believe that if ten coin tosses individuals will often personify an analoin a row come up heads, the probability of a gous sort of memory. For example, the

tail on the eleventh toss will be substantially research of White, his students, and

greater than one-half. This conviction is students of his students (Burton, Kates,

related to a garbled version of what is and White 1978; Kates 1962; White 1964) 13
has shown that many people view natural never-follow the dictates of any normative

hazard events such as flood, drought, hail, method in making their own decisions about

and tornadoes as being sent by a conscious what to do in risky situations. They may

Being who somehow keeps track and misjudge or misunderstand probabilities.

would not send one flood on the heels of They may focus on some irrelevant or emoanother. Others see such events as cyclical, tional facet of the problem. Or they may

where again the occurrence of the event mean different things when they use words

guarantees a period free from it. such as "prefer" and "willing-to-pay" than

experts assume they ought to mean.

"Even when they understand probabilities

and how to use them, people commonly Not-So-Ratimal Models: Problems

overweight low probability events-that is For Public Agencies

assign a "decision weight" to low probability

events that is higher than the "objective" or In the context of purely personal decisions, no

"true" probability of the event (Kahneman one but the decision maker stands to lose

and Tversky 1982). from the use of a flawed version of the

normative model. If an individual wants to

" Individuals are highly susceptible to gamble on coin tosses while assuming the

nuances of situation framing in deciding coin in question has a memory and a will, that

between alternative gambles. (e.g., concen- is his business. (Economists may be upset

trating on expected fatalities in one framing because this calls their entire model of the

leads to different preferences over the same rational, self-seeking individual into question,

gamble than does concentrating on ex- but hardly anyone else will care about that.)

pected lives saved (Kahneman and Tversky If another individual allows small differences

1982; Tversky and Kahneman 1981)). in the words used to describe his problem to

influence his decision, he pays whatever price

" Subjects in laboratory experiments com- is involved. But the number of decisions that

monly exhibit preference reversals over are purely personal is surprisingly small, once

gambles-that is, they commonly act we begin to take account of the many forms

irrationally in the face of uncertainty by, of interdependence implied by such features

for example, saying they "prefer" lottery of modem society as crowded streets, buildticket A to lottery ticket B (where A differs ings, and highways; public (tax) financing of

from B in probabilities and sizes of win- much health care; and welfare programs

nings) but then indicating a higher aimed at preventing the worst ravages of total

willingness to pay for B rather than for poverty. In such societies, driving while

A (Lichtenstein and Slovic 1971; Slovic drunk, for example, endangers not only the

and Lichtenstein 1983; Grether and driver but also others on the road, and the

Plott 1979). cost of any care required for resulting injuries

would likely be shared generally across

Thus, we can see, at least in a preliminary society through such programs as medicaid or

way, that there is reason to expect to find that through the shifting of charitable-care costs to

lay citizens will not always--indeed, may privately insured patients. So, even what

14
might seem on the surface to be a private different type and sited in different geologidecision about taking risks can have diffuse cal conditions, fails. For the population, the

social consequences. Therefore, all citizens news of one dam failure has led to a large

have, in principle, an interest in how those increase in subjective probabilities of dam

decisions are made. They would, if they failures generally.

could be asked, presumably say that accurate

information and sound methods should The Corps, in an effort to explain the

be used. benefits of yet another dam project, talks

publicly about numbers of flood deaths

An agency such as the Corps of Engineers, occurring with or without the dam.

charged directly with the spending of public People's feelings about the project may

money to achieve public ends, has an obliga- indeed be affected by the use of a "deaths

tion to use accurate information and sound occurring" frame rather than a "lives saved"

methods in dealing with the uncertainties that frame. says these citizens

face it. But its decisions cannot in general be should accept an

made and imposed unilaterally. It therefore The Corps is considering a request for a expected value decision

has an interest both in understanding how the Section 404 permit that involves a wetland criterion as the

private citizens with whom it interacts make drainage scheme. Its consideration will appropriate one...

their decisions and in encouraging the use of include an examination of prospective Many concerned

the best available methods and information by ecological damages to the wetland. Ulti- indi m

those citizens. Consider a few hypothetical mately, the Secretary of the Armys indeed prefer a more

but not farfetched examples: on the permit will have to be based, in part,

on the expert judgment of ecologists about conservative criterion,

The Corps is planning a flood-control the probabilities of various types and levels such as acting to

reservoir project and finds, using the best of harm. But there is no requirement that minimize maximum

available historical hydrologic data as well even entirely rational citizens should also possible damages.

as sound methods for evaluating flood accept these judgments. Further, there is

damages avoided, that the proposed dam nothing that says these citizens should

seems to be justified in National Economic accept an expected value decision criterion U

Development account terms. But toward as the appropriate one for such a decision.

the end of the planning cycle, a severe flood Many concerned individuals might indeed

occurs (say the 500-year flood). The prefer a more conservative criterion, such as

residents of the region, hearing "500-year acting to minimize maximum possible

flood" and subscribing to the cyclical view damages.

of natural hazards, oppose the dam as

unnecessary because another flood is not The message of these examples is that simply

"due" for about 500 years. understanding the classical normative model

of risky decision making is not enough for a

Another dam project, with a similar public agency that must interact with a range

purpose, runs into trouble with the local of citizens in order to do its job. Such an

population that must provide cost-sharing agency must be prepared to find its plans

when an existing dam on another river, of criticized on the basis of apparently irrational

15
fears (or equally irrational overconfidence); to • Even in more mundane and familiar

have its judgments questioned by outside settings, experts may be quite unreliable

experts; and to have its decision methodology judges of risk. Freudenburg (1988) reports

rejected as insufficiently conservative (or as too on studies of the inability of physicians to

conservative) by the public, diagnose disease from case histories and

examinations and on the inability of

Concern about exactly this problem- geotechnical engineers to predict correctly

disconnection between expert or agency the height of an embankment that would

assessments of and recommendations for risky cause a clay foundation to fail.

situations--has inspired a substantial amount

of literature (For recent examples, see Institute And even when bias and lack of skill are both

for Philosophy and Public Policy 1988 and absent, experts may face very fundamental

...not everyone who Slovic et al. 1991). Much of this literature has constraints on their ability to deal with risk.

qualifies as a "Public" a tone in which condescension and frustra- For example, philosophers of science talk

decision maker...also tion seem mixed in equal parts. "Why can't about "interference effects" that may occur

qualifies as an expert in they be more like us?" expressed Professor when technologies are combined in new ways.

understanding Higgins' frustration with the ways of women; it It may be impossible to predict when such

Unertainty. might stand for the technocracy's feelings effects will occur and what form they will take

toward the public's ability to deal with risk. (Applebaum 1977; Hacking 1986).

U Two points, however, must be stressed by way Thus, there appear to be several difficulties

of putting this concern in perspective. First, even with expert risk assessments. Whatever

not everyone who qualifies as a "public" rules of thumb the lay public may use to assess

decision maker--certainly not every legislator the assessors, it would be surprising if there

or executive or regulatory agency head-also was collective agreement to put a "decision

qualifies as an expert in understanding uncer- weight" of one on expert predictions of risk.

tainty. Thus, this individual human frailty is Since in many of the situations that form a

doubly a matter for collective concern. But backdrop for the "we-us" lament, there is at

second, and at least as serious, there are least some reason to see corporate or agency

reasons to be concerned even about the ex- self-interest served by low levels of risk

perts in our public decision-making structure. prediction, much higher levels may well enter

Consider the following: individual calculations with nonzero weights.

In the presence of such fundamental defects in

Sometimes expert expressions of confidence our knowledge, skepticism and conservative

(of the low probability of hazard) seem to be rules of thumb may seem only prudent even to

related to political and financial pressures to educated, objective, and unemotional memkeep programs on track. For example, bers of the public.

NASA's official estimate of the probability of

shuttle failure, 1 in 100,000, is wildly The final nail in the coffin of hope for rational

different from the recorded rate of 1 in 25 or public decisions about risk has been thought

1 in 50, depending on the calculation used to be that if there were no a priori rational

(Freudenburg 1988, p. 47). grounds for devaluing a particular risk

16
assessment, the public would still be in a Sources of Tension Between

sense unreachable. The combination of Expe &and Public in Risk Analysis

faulty understanding of risk, flawed manipulation of new information, and tendencies To provide some structure for our catalog of

to try to take the probabilities out of risk difficulties, or rather, we should say, the

would form too powerful a block to learn- causes of differences between individual and

ing. While this may yet prove to be so, agency answers to questions of how to

there are fragments of evidence that, at least respond to risk, we provide the schematic of

where people see their self-interest immedi- Figure 11-3. This shows the individual as

ately involved, careful attention to the having two sources of information about risk:

details of risk communication can make direct observation of risks and communicaa useful difference (Bohm 1990; Smith tions that describe risks. By "direct observaet al. 1990). tion" we mean such opportunities as living ...in order to take

through years of climate and weather in a advantage of

But in order to take advantage of opportuni- particular location; driving an automobile on opportunities for

ties for careful communication, it is necessary particular roads at particular speeds; taking careful communication,

to understand where these many sources specific drugs; eating foods; watching the it is necessary to

of controversy come from. On the basis of processes of birth, growth, and death in other understand where these

that understanding, it should be possible humans; and so forth. Much of this observato develop strategies aimed at making the tion provides us with information about the c o of

final collective decision on any program or risks we are running and most of us make at controversy come rm.

project as rewarding as possible for society least some effort to process and extract that

at large. To those twin ends-understanding information.

and strategy formulation-the rest of this

chapter provides a brief overview of sources We also have available a massive amount of

of difficulty with the rational model. Some indirect irtformation about risk-indirect

of these sources are internal to individuals, because it has been processed by others and

and some of these in turn represent then communicated to us in words, numcognitive or logical failures, while others bers, pictures, or mixtures of those means

are simply produced when different individu- of communication. Indirect sources include

als make different choices and use different all of the mass media (TV, radio, newscriteria for choosing, all equally valid and papers); stories and reports brought to us

internally consistent. Some difA -zulties by other individuals; specially targeted

arise, on the other hand, because in stress- efforts to inform us, such as newsletters

ful situations, emotional modes of thought from concerned groups, from companies

and behavior may take over. And still that want to sell us a service or product,

others are produced by social pressures and and from public agencies that want us to

interaction. Chapters III-V go into these share their view of a particular situation

problem areas more carefully, as preparation or policy.

for the final Chapter VI in which lessons

for action are drawn from the catalog of Both our own observations of, and the

difficulties. indirect communications we receive about,

17
Figure 11-3

A Schematic of Sources and

Processing of Information About Risks

DIRECT INDIRECT

Observation of Risks Communication

about Risks

INFORMATION INFORMATION

INITIAL FILTER INITIAL FILTER

Attention

Attention Motivation

Motivation

Format/Medium

Filtered information

EMOTIONAL FILTER 4-COGNITIVE FILTER

Reaction to Authority Assessment of Source:

Retreat/Denial Characteristics, Reputation, Interest

Influence

MIXED FILTER

Response to Framing

Taking Account of Auxiliary Dimensions

Cognitive Dissonance

EXTERNAL SOCIAL PRESSURES COGNITION/INFORMATION PROCESSING

Cultural Biases Estimating Probabilities

Social Amplification Dealing with Independence

Updating Probabilities

Influence Weighting Outcomes

Risks _Ranking 

18
risk may be thought of as subject to several merely meant to be suggestive and an aid in

filtration stages. Initially, we filter out infor- interpreting the sorts of problems that have

mation that arrives when we are too busy to been observed and commented on in the

be attentive, or that does not seem to speak to field.) We distinguish three sorts of filters:

our personal situation. For example, informa- emotional, cognitive, and mixed.

tion about tornadoes in Oklahoma may not

be attended to if we live in Massachusetts and The idea behind the "emotional" label is that

have never seen or heard of a tornado touch- we are sometimes not so much thinking

ing down anywhere nearby. Reports of the about what we see or hear as simply reacting,

dangers of rock climbing, long-distance perhaps in rather primitive ways, to the

swimming, or urban rollerskating may well be information that has reached us. Two

filtered out if we have no intention of ever principal types of reaction we distinguish are,

pursuing any of those activities. But even a first, to the information itself and, second, to ...we filter out

"TV news report of flash-flooding danger in the source of the information. The first infonnatiou that arrives

our local area many be essentially ignored if reaction may result if in fact that information when we are too busy

we are trying to balance a recalcitrant check- is very threatening. For example, a story to be attentive, or that

book when the report appears on the TV about the dangers of smoking could be very does not seem to speak

news. In the case of indirect communication threatening to a heavy smoker. Similarly, to our personal

about risk there also seems to be another stories about flood risks threaten floodplain situation.

initial filter, one triggered by the medium inhabitants and observing a bad automobile

containing the message. As an extreme accident threatens a person who habitually

example, consider junk mail and phone calls. drives very fast or who drinks and drives. U

An individual may very well have decided to Such immediate threats may, as discussed in

ignore all such messages and may throw away more depth in Chapter III, trigger retreat and

the one and hang up on the other without denial--refusal to think about the problem or

receiving even a fraction of the intended to take steps to reduce the threat.

message. Similarly, some (even many)

individuals may change radio or TV stations The second broad sort of reaction is to the

when an informative talk show comes on. source of the message. An especially compliOthers may read only certain parts of their cated cause of such reactions may be the

newspapers, be it comics, sports, business, or connection formed by the individual between

editorials. the threat implicit in the risk information and

the authority that is perceived to be its source.

The next layers of filtration act on information This reaction may well take the form of

that has "survived" the first filters and entered rejection of the information because the

our consciousness. These secondary filters source of the information is seen as having

may be thought of as determining how the betrayed or abandoned the individual

surviving information is classified and receiving the message. In effect, the authorinterpreted in preparation for processing. ity is seen as parent to the recipient's child;

(The order of these filters in Figure 11-3 does and a failed parent at that because it is

not reflect any sophisticated model of human merely informing about a risk rather than

consciousness, emotions, and intellect. It is "fixing" it.

19
A second filter between receipt and processing contrary to fact" out of the risk information

of information we call "cognitive" to empha- received. The first of these activities, the

size that sophisticated thought and reasoning resolution of cognitive dissonance, has been

are involved in its application. A major recognized for many years as a very human

activity of this filter is to judge the combina- information processing activity (Festinger

tion of message and source and check for 1957). Roughly, it is what we try to do when

grounds for rejection. As a very simple new information conflicts with current beliefs

example, consider an individual who or emotional positions. For example, an

encounters an advertisement in a major news individual is emotionally and financially

magazine that tries to explain that concern committed to a major environmental group,

about exposure to carcinogens in food has but the group takes a position on the risks

been blown out of proportion, that the in- from a specific farming practice or chemical

creased risk of some of the better-known scare that objective sources of information seem to

examples is so tiny as to be nearly undetect- agree is dead wrong. How does the indiable across large populations. The cognitive vidual respond? By filtering out the objective

filter checks the source of the ad. If it is information on the grounds that it is only

Monsanto, skepticism may dominate the reac- apparently and not "really" objective? By

tion. If the ad has been jointly sponsored by abandoning belief in the group? Or by some

Monsanto and the Environmental Defense quite sophisticated internal admission that the

Fund, a very different response will probably group, while worthy of continuing support,

be called up. In general, this filter may be was surely wrong on this call? A similar

thought of as an examination of the message- difficulty would arise for an individual whose

institutional source pair in terms of such livelihood was threatened by a policy suggescharacteristics as the perceived fairness and tion that intellectually, the individual knew to

balance of the message; apparent sincerity of be socially desirable. In such situations,

the message; the likely objectivity of the something has to give, and often it appears to

source; and the apparent competence of the be the emotional position that ends up

message construction. Failure of the pair to dominating behavior.

pass some part of this examination may relegate the message to the wastebasket as surely Response to framing is another well-studied

as if it had arrived in a piece of junk mail, even phenomenon of the literature on individuals

if considerable expense has been put into and risk. Simply put, the evidence is that

putting the message in a popular medium. many, though by no means all people, will

respond differently to two mathematically

We label the third filter "mixed" because it identical pairs of risky choices if one choice

seems that elements of both emotions and pair is couched in negative (e.g., loss of life)

cognition are involved in its processing work. terms, and the other is stated in positive (e.g.,

The examples we give in Figure 11-3 of this saving of lives) terms. We attribute this

filter's activity include the resolution of difficulty to the mixed filter because it is

cognitive dissonance, the response to particu- clearly not a purely cognitive phenomenon

lar aspects of message framing, and the but has something to do with our emotional

construction of what we might call "situations responses to the terms being used. 20
The third activity we categorize as part of the trian risks. This may be related to the way

operation of the mixed filter is related to the these different sorts of events are treated by

response-to-framing problem but seems to be the media.

worth a separate mention. We call it the construction of situations contrary to fact. The Once a probability of an event is formed

best examples of this come from laboratory and new information bearing on that

experiments and other investigations of the probability becomes available, individuals

problems that individuals have with risk, and have difficulty making the called-for

we describe these and give examples in adjustments. Technically, this should be

Chapter IV. done using Bayes' theorem, which not 1

person in 10,000 has probably ever heard

In Figure 11-3 we show the information that of (see Chapter IV). But even allowing for

survives and is modified by the filtration pro- the necessity of using rough, intuitive ...evice indicates

cesses going to a cognitive processing opera- methods, it appears that people make that individuals tend to

tion. In this operation an individual uses the incorrect judgments about how important overestimate the

surviving information to estimate and update particular bits of information are. They probability of rare and

subjective probabilities of the events in ques- may, for example, overvalue in their spectacular events and

tion (flood, lung cancer, auto accident, or revision the results of one test, ignoring the to underestinate the

whatever); to deal with the implications of information about the test's diagnostic probabilites of

stochastic independence where that is relevant powers; or they may seize on some infor- o f

(as it certainly is with fair coins and other mation that appears to "explain" how the peian ri

gambling devices and is generally thought to events in question occur.

be for most naturally hazardous events); to

construct auxiliary weighting schemes for out- As already noted, people commonly have a

comes (technically often referred to as utility great deal of trouble with the notion of

functions); and to rank risks and make de- independence and appear ready to go to

cisions about behaviors and choices. In all considerable mental lengths to construct

these operations we observe further difficulties theories that deny independence in risky

that imply that policies and projects decided situations that involve repeated trials or the

on the basis of expert judgments and agency simultaneous occurrence of several events.'

weighting criteria may well not be acceptable

to lay individuals. Consider, for example, the While no subjective weighting scheme for

following list, and see Chapter IV for more outcomes can, a priori, be said to be wrong

detailed discussion: or illogical, some are more intuitively

appealing than others and some are more

* The evidence indicates that individuals tend obviously consistent with observed behavto overestimate the probability of rare and ior than others. A pattern that researchers

spectacular events and to underestimate the find with surprising frequency is noninprobabilities of common and more pedes- tuitive indeed: this is a pattern expressing

3

A joke that uses this proclivity for its humor involves the person who tries to board a plane with a bomb in his briefcase.

When caught, arrested, and questioned, he explains his behavior by saying that he'd heard the chance of a plane having a

bomb on board was 1 in 10,000. He figured the chance of there being 2 on this plane must be I in 100 million; so he was just increasing his and everyone else's safety.
aversion to risk when gains are at stake but a possible influences on behavior under uncerseeking of risk when losses are in question. tainty that come to us with the belief system we

(As discussed in Chapter IV, however, there adopt from the culture we grow up in. For

is a problem in trying to infer weighting pat- example, a person raised in a fundamentalist

terns from observed behavior when prob- Protestant religious household may be ready to

abilities are also subjective and subject to the see God's hand and God's judgments in natural

problems caused by the difficulty of accept- events. This makes it hard for such a person to

ing independence.) see that the normative model for dealing with,

say, flood risk, is of any use. On the other

*Perhaps the most damaging phenomenon of hand, Western culture generally enshrines the

all to the notion that lay people can deal power of human scientific and technological

rationally with uncertainty is one already knowledge and assumes that we can eventually

referred to--that well over a majority of know nature's secrets and control nature's

daaging phe"omenon subjects in laboratory tests exhibit what is processes. This bias, too, may make it hard to

of all to the notion that known as "preference reversal." This occurs accept ran-domness and independence associlay people can deal when they are asked to give a preference ated with natural events.

rationally with between two lottery tickets and subsequently

utainty is ...Iwn to say what price they would have to be paid The second aspect of social influence, social

for each ticket to give it up if they owned it. amplification, is a more subtle but also perhaps

When the choice is between two tickets that a more powerful notion. It involves the reac- reversal."

have similar expected values but very different tions of individuals to events, both as individudispersions of potential winnings, individu- als and as members of hierarchies and groups, U als commonly express a preference for the and the interaction of those individuals with

ticket offering lower dispersion, even if its others in such a way as to amplify the perexpected value is also a bit lower. But when ceived threat from the event. ("Amplification"

asked for the prices they would require to is used here in a generic sense of changing the

sell each of the tickets if they owned them, strength of; the process may lead in either

these same individuals commonly name a direction of increasing or decreasing the genhigher price for the wider dispersion ticket. eral perception of risk.) An example of ampliSince we normally think that "preferred-to" fication in the plus sense could be found in a

and "would-want-a-higher-selling-price-for" situation in which local politicians pick up

amount to the same thing, these experiments signals of concern from constituents about a

seem to many to suggest that people become proposed dam, for example, and, stressing the

hopelessly muddled when faced with risky dangers, bring this to much wider attention

decisions. while giving the concerns new legitimacy. This

feedback loop could in fact be engaged for

The final box in Figure 11-3 is that labeled another round or two and lead to massive

"external social pressure." It is shown as influ- rejection of the required local financing.

encing the outcomes of all the filter operations

and of the cognitive processes. Within the With this introduction and framework in place,

box, two specific forms of social influence are we now turn to a more careful and detailed catnoted: cultural biases and social amplification. alog of difficulties with, or limitations of, the

2 . . The first is meant to suggest the range of normative model for making risky decisions.
Filte for Risk Communicaion

The informal model of risk perception and those of us who grew up in the 1940s and

analysis that we sketched in Chapter II 1950s were more likely than not to have

emphasized the role played by "filters" watched one or both of our parents smoke

between external stimuli and internal infor- regularly. If those parents have died-or if

marion processing. These filters operate both they have been treated for cancer, emphyon the risk information gathered directly by sema, or heart disease-we have an observaour own senses and on information about risk tion, in retrospect, on the health risks of

provided to us by others as, for example, in smoking. (We also have an observation if

television documentaries, magazine articles, they are still living and in good health; an

and conversations with friends. And the observation with a very different message.)

filters seem to be created to serve different Or consider climate risks. The longer we

ends, some apparently more useful to the have lived in one place, the more observaindividual than others. For example, one sort tions we potentially have on such climatic

of filter may prevent new information from and weather risks as flood, drought, hail,

being noticed or remembered seemingly in hurricane, and tomado. And as a final

order that concentration on other, more illustration of the notion (without any claim

immediate concerns will not be lost. Another to having presented a complete catalog),

sort, on the other hand, may change the think of the thousand and one risky things

nature of the information that gets to the each of us does every week from commuting

brain's processing operations to make it by automobile to operating power tools,

consistent with a comforting, but not from taking drugs (prescription,

necessarily serviceable, version of what is nonprescription, alcohol, caffeine) to

being observed. exercising irregularly and under stressful

conditions. Each such action and its

We divided these filters into four broad types: consequences constitute an observation that

the initial or consciousness protecting, the can help us form our own judgments of the

emotion-based, the cognitive, and the mixed risks we are running.

emotional and cognitive. Within each type

we distinguished more than one motivation On the other hand, by far the greatest

for the filtration action and more than one amount of information available to us about

possible outcome of the filter's operation. almost any risk we care to name comes to us

In this chapter, we go over this material indirectly: from friends or acquaintances

more carefully, reporting on their experiences, from the

media of mass communication, or from a

IniUtl Filters third- or fourth-hand account that relays to

us the content of a story in the media. In

It is possible to gather some information from interpreting our own, direct, experience, we

our own, direct experience. For example, inevitably suffer from the problem of small 23
sample size. Furthermore, although we may just as well have been playing a sport, reading

have some personal experience with many a book, or finding our way in a part of town

risks, there are inevitably many, many more we are unfamiliar with.

that we can know nothing directly aboutwhether because we actually do not have Motivation and Ability

relevant experiences or because we do not People develop strategies to select informaknow what our experience is. Thus, it is very tion, including risk information, that they feel

unlikely that any given U.S. citizen has any is relevant to them. In the technical literature,

direct experience relevant to assessing the the general phenomenon is sometimes

risks that nuclear power plants pose. And referred to as the "selection process." The

while we may all be walking "observations" major criteria for selection are ability and

on the dangers of pesticide residues on food motivation (Chaiken and Stangor 1987). ...for most ara of

or of lead in the general environment, we Ability refers to the physical possibility that modern life...our risk would be very unusual if we actually knew the receiver can follow the message without

perceptions are ilIely to anything at all useful about our experience. distraction; motivation to the readiness and

be more a product of Thus, for most areas of modem life relevant to interest of the receiver to process the message.

our exposure to indirect agency responsibilities, our risk perceptions

informationespeciany are likely to be more a product of our expo- Two conditions have to be met to satisfy the

stories andi anabsis in sure to indirect information-especially criterion of ability: the information has to be

stories and analysis in the mass media--than accessible; and the receiver must have time to oheroass media-tha of personal experience, process the information. Several factors

of personal e ii~ee, influence the motivation of a receiver to

Afttnin process the information. The information

For both sources of information, similar initial content has to be relevant (referring to

filters are usually in operation. We have personal interests, salient values, or selfcalled these "attention" and "motivation" esteem), and it should trigger personal

filters. In simplest terms we mean to suggest involvement (with the issue, the content, or

that whether or not a direct experience or an the source). Both motivational factors are

indirect message about the experience of reinforced if the receiver has some prior

others is used to construct a judgment about knowledge or interest in the subject or is in

risk depends, first, on whether we attend to it, need of new arguments to back up his/her

and second, whether we are motivated to point of view. (Clearly, these points are

make use of it. Our ability to attend depends relevant to the design of risk communication

on what else we have to do or think about. At activities. See Chapter VI.) If both criteria are

the extreme, an obsession with a career or met, the individual selects the information.

marital problem could effectively block However, to economize further on time, he or

messages from nearly every other aspect of she is going to evaluate whether it is necessary

life. More usually, if we are devoting consid- to study the content of the information in

erable attention to one task or interest, we do detail or to make a fast judgment according to

not have attention "left over" for much else. some salient cues in the message received.

The example we used in Chapter II was The first strategy refers to the central route of

balancing a checkbook, but the activity could information processing, the second to the

24
peripheral route (Petty and Cacioppo 1986; information processing (cognitive) center.

Renn and Levine 1991). The central route is We consider three sorts of subsequent filters:

taken when the receiver is so highly motivated those based on emotional reactions to the

by the message that he or she studies each message or experience; those based on

argument carefully. The peripheral route is cognitive processing applied to peripheral

taken when the receiver is less inclined to deal features of the message rather than its content;

with each argument but forms an opinion or and what we call mixed filters, which seem to

an attitude on the basis of simple cues and display features of both emotional reaction

heuristics. and cognitive processes.

Medim and Fonmat Emotional Filters

One other matter that we have chosen to

discuss as part of the initial filtering or Within this category of information filters, we message aimed at

selection process is the role of medium and distinguish two major types: denial and a mass audience,

format. As common sense suggests, any "defensive passivity," and reaction to author- including a message

message aimed at a mass audience, including ity. Within each type, several variations on about risk, is more

a message about risk, is more likely to be the main theme may be identified. likely to be attended to

attended to if it arrives in an attractive and if it arrives in an

accessible "package." Everything else equal Dena ad Psity attractive and accessible

(level of distraction, motivation, ability), a Denial may usefully be thought of as an

boring package will be more likely to be admission of inability to cope. For example, "package.

filtered out than will an intriguing and we may deny overwhelming threats or

attractive one. Thus, for example, a four- or seemingly all-pervasive risks, even though

five-page single-spaced letter is far less likely small (such as one might understandably

to be read than a much briefer one, perhaps believe lurk in the food we eat). But denial

accompanied by a colorful brochure. A radio can itself take several different forms.

spot might get more attention still. And a few

minutes on TV, with action and not just "Perish the Thought"--Denial of

words, might be most effective of all at getting Unwanted Thoughts

attention. Commercial advertising agencies Denial can refer to a blocking from awareness

make a living by devising "best" ways to get of certain threats; we simply do not think of

attention and transfer at least modest amounts them. If we have been warned about a threat

of information about products and services we forget the warning. This is what we

within constraints on budgets and on accept- usually think of as constituting denial, and

able media, images, and vocabulary, this conception has a certain basic intuitive

believability (Freud 1966).

Now let us follow the information that has

passed the initial filtering process and discuss Commonplace evidence of this type of denial

subsequent reactions to it on the part of the is presented to many of us on a monthly basis

individual. These reactions we are also calling when our credit card bill arrives. We are

filters, since they determine what part of the incredulous as we suddenly remember the

original message, if any, gets through to the purchases we have made and have 25
conveniently "forgotten." Would we have so going to be you" (Wolfenstein 1957). The

readily forgotten a promise of a $1,000 check enormous power of this psychological

due us at the end of the month? Thus, denial mechanism in denying danger is shown in

is a motivated blocking from awareness of people's responses to questions about the

unwanted thoughts. aftermath of a nuclear blast; most people

respond that after the blast they would do

"What, Me Worry?"--Denial of what they could to help the injured.

Unwanted Feelings Under certain conditions, denial may be

There are other, more paradoxical forms of functional. When threats are remote, it would

denial. One may, for example, acknowledge be very troublesome to become anguished

that a very dangerous situation exists but not about all possible disasters that could befall

feel worried about it. In other words, the us. And when faced with threats about which

The enormous ower of external situation is acknowledged, but the one can do nothing, it perhaps makes sense to

this psychological feelings aroused by this danger are blocked not get oneself worked up. But in other

mechanism in denying from our awareness. This can lead to a circumstances, the mechanism of denial may

danger is shown in pernicious response to danger, because it may be extremely ineffective, even irrational, as a

people's responses to preclude feelings from acting as a spur to means of coping with risk. If the husband

questions about the protective action despite receiving adequate whose wife was undergoing surgery had

aftermath of a nudear warning from authorities regarding impend- allowed his denial to prevent him from taking

blast, most people ing danger (Freud 1966; Fenichel 1945). appropriate action, what would the consequences have been? At the very least his wife

respond that after the A different sort of example of this type of would have felt abandoned in a moment of

blast they would do denial, called isolation of emotion, is the great need.

what they could to help husband whose wife requires serious surgery.

the injured. In the days prior to surgery he is solicitous To cite another, more general, example of the

toward her and takes time off from work to be irrational nature of denial, consider the

near her; but oddly enough, he feels very unhelmeted motorcycle rider who places

Ulittle. Only when the surgeon informs him some ill-defined James Dean image of mascuafter the operation that all has gone well does linity above his own physical safety as he

the husband experience a welling up of ventures forth blithely onto the highway,

feelings, and only then does he realize how protected only by his adolescent sense of

frightened he has been all along, invulnerability. By a circuitous logic, this

behavior could be called rational (i.e., using

The Myth of Personal Immunity reference to values, etc.), but to do so is to

A third type of denial is that of myth of confuse the terms rational and understandpersonal immunity. This is a belief that, able. The behavior is indeed understandable,

although a very real danger is acknowledged, but only by reference to the irrational elethe disaster will strike somewhere else. "The ments of his makeup.

other guy" will suffer. It is almost a clicht that

recent victims of disasters, when interviewed, Inner Peace as False Security

say that "this is the kind of thing that always Another aspect of denial is the tendency to

happens to someone else. You never think it's equate internal feeling states and external

26
states. People during times of threat some- and hope you will spare my life." It is

times believe that if they are "good," every- suggested here that this well-documented

thing will turn cut all right. Similarly, we animal behavior has a counterpart in human

sometimes believe that if we remain calm response to threat. When faced with an

inside, and do not get upset by a threatening overwhelming threat, the public may respond

situation, that outside events also will remain with what seems to be paradoxical passivity.

calm; and conversely, that feeling upset will Instead of taking protective action in their

only lead to external disaster (Wolfenstein own self-interest, they may adopt a fatalistic

1957). It is as if we are trying to control the attitude, saying, "It's all in God's hands now,"

gods by controlling ourselves. Young chil- or "You can't run from fate." In risk literature

dren do not make a distinction between that this is commonly referred to as an "external

which is internal and that which is external, locus of control," a belief that the direction

and one suspects that this tendency operates and outcome of one's life are determined by

in adults as well during times of danger. forces outside oneself.

The Spectacle Response Locus of control has traditionally been a

The early stages of an actual disaster can elicit helpful lens through which to observe risk

what might be callcd a "spectacle response." response, but it obscures as well as illumiHere not only ;, ,darvr de~aed, but the nates. The passivity we are describing is not

danger acts as a rmagnet -and .::toally draws an ever-present personality factor but, rather,

people into dangerous situationr.,. Examples a threat-induced, temporary, regressive

are those who go to the shoreline during response whose psychological meaning is not

predicted times of seiche, or those who visit self-evident and thus requires further analysis.

fires. What is at work here? Why are people It is argued here that the passivity described

drawn to such experiences? Perhaps it is the above is actually designed to serve a protective

case that such occurrences are experienced by function, albeit irrational in its method. It

the individual as an opportunity to face and to represents the individual's desire under

master childhood fears. Evidence for this extreme threat to seek an early childhood

reasoning is that at these times there is often a dependency upon a protective, omnipotent

sense of elation experienced, suggesting that power. And yet recognizing that this is not

some emotional burden has, at least tempo- possible, the passivity also expresses to the

rarily, been lifted. superior force, like the defeated dog, "I offer

you my throat, have mercy on me" (Fenichel

Passivity in the Face of Threat 1945). Conversely, active attempts at fending

Two neighborhood dogs circle each other off (defeating) the threat by taking active

menacingly. Suddenly there is a lunge, a precautions may seem to the individual a

frightening bit of thrashing about, and one of form of aggressive pride that will only prothe dogs rolls on its back in a posture of total yoke greater retaliation by the gods.

submission. Communicated to the victor is

the message, "Yes, I know you are far stronger This phenomenon, sketched in stark terms

than I, and it is no use to struggle. My only here, would hardly be expected to manifest

hope then is to throw myself on your mercy, itself in pure, undiluted form, at least in a

27
psychologically healthy population. But this of combating the crumbling sense of meaning

mode of response phenomenon, like many of brought on by disaster (Wolfenstein 1957).

the others discussed in this section, may act as

a subtle counterpoint theme to more observ- Mastery through Observation. Under

able, rational reactions to threat. In their very conditions of threat, the tendency to regress

subtlety lies their power, for these processes toward childlike thought processes may lead

operate just out of reach of awareness, out of people to believe that staying at home and

rationality's reassuring grasp. watching things will afford them protection.

This is a manifestation of the primitive belief

*The Tendency to Remain in Familiar that danger can be controlled by watching it,

Surroundings Despite Danger and a feeling that if we keep an eye on an

Different types of dangers require different object, it cannot harm us (Wolfenstein 1957).

The desire to remaini t kinds of responses to avoid harm. Certain As primitive and unrealistic as this may

home during times of natural hazards such as hurricanes or floods sound, it may be part of the foundation of the

threat may be an may necessitate leaving one's home tempo- "scientific coping style" discussed later in

attempt to counteract rarily, or even permanently, as the most Chapter VI. What we can know about and

an intense feeling of effective safety procedure. But it is well understand is, in a sense, tamed and masaeiandonment. known that many people are very reluctant to tered. And by being able to predict, we feel a

leave their homes, and they place their lives in sense of power, as if we had control over the

great jeopardy by ignoring warnings to phenomena observed. It also is clearly related

evacuate. Obviously, powerful psychological to the "spectacle response."

forces, which can overcome our realitybounded tendency toward self-preservation, Mastery through Repetition. But what of

must be involved. There are three closely those who have survived terrible disaster and

related forces at work here, as described have seen their homes destroyed and their

below. belongings lost? How can we understand the

desire of many people to return and rebuild

Counteracting Feelings of Abandonment. on the same location despite the continuing

The desire to remain at home during times of possibility of recurring danger? More than

threat may be an attempt to counteract an economic and material considerations seem to

intense feeling of abandonment. As stated be involved in such decisions. What seems to

earlier, one's unspoken faith in a variety of underlie this behavior is an attempt to master

protective sources may have been shattered the traumatic event by repetition. The person

by the disaster, and all that remains to provide places himself in the same situation in an

comfort is that which is familiar. Our home attempt to restore an equilibrium that was

and belongings are the physical embodiment destroyed by the force of the disaster. He

of our lives: our values, beliefs, our history, rebuilds, not in hopes of repeating the

and our relationships. And thus, the home, disaster, but in hopes of bringing about a

traditionally seen as a refuge from the world, positive outcome next time. By taking action

takes on even greater emotional significance. and rebuilding, he is transforming a passively

To surround oneself with the immediate experienced trauma into an actively directed

evidence of the meaning of one's life is a way successful outcome. This psychological 28,
tendency is related to our observation of authorities Cassandra-like in their impotence or

children's games during wartime. These can turn the authorities into scapegoats whose

games consist of repetition of the very themes advice is actively resisted.

that terrify the child: assault by an overwhelmingly powerful enemy. In these games The following is a brief description of the various

however, the outcome is always a heroic forms that this phenomenon may take and the

victory by the forces of goodness over the depth of feeling elicited.

power of chaos (Waelder 1933).

"Why Hast Thou Forsaken Me?"--Feelings of

These games enacted over and over again Abandonment

with the same positive outcome are really very If feelings of intense vulnerability are evoked in

serious business to the child, an attempt to times of disaster, a deep sense of abandonment

restore inner peace and balance following a by authorities may be experienced. Authorities

shattering experience. And so, too, the urge in this conception are thought of as parental

by disaster victims to return and rebuild may figures who have failed to perform their crucial

be folly from one point of view, but seen from protective task. In its strongest form, this

a psychological perspective is compelled by perceived abandonment could result in despair.

the urge to restore the internal forces of order But even at lesser levels of disaffection, warnings

over the power of chaos. could be ignored because authorities are no

longer seen as potent protectors (Rado 1942).

As we shall see in the following subsection,

the impact of expert advice and warnings Authorities as Scapegoat

from authorities on these powerful mecha- When faced with an overwhelming uncontrolnisms of denial may be profound, though not lable threat, all of the carefully constructed laws

always in the desired direction. of cause and effect, right and wrong, by which

we have governed our lives, may be threatened.

Reaction to Authority Emile Durkheim coined the term "anomie" for

Ideally, when the public is faced with risks, this intense state of personal breakdown of social

the desired response would be one based on meaning, and demonstrated that it can lead to

an objective assessment of danger. As we suicide (Giddens 1972). But the human spirit

have seen, however, the term "objective does not yield easily. To avoid this ultimate

assessment of danger" is an oxymoron. breakdown, that is, to maintain a crucial sense of

Dangers are filtered through complex order and justice in our universe when things are

psychological processes (such as denial) seemingly out of control, there is a tendency to

that heavily influence perception, attitude, blame someone. If a scapegoat can be identified,

and action. then the universe can still be seen as lawful and

controllable. This scapegoat is often the very

Can the public's lack of objectivity be effec- authority whose responsibility it is to issue

tively countered by clear warnings from warnings and outline precautions (Rado 1942).

authorities? Certainly this is possible to an

extent. However, the same psychological Another way of thinking about this mode of

forces that lead to denial can also render response is to see that clear warnings of danger ,99
may threaten the public's wish to deny the authorities to protect one from danger. In

danger. Ironically, it is the warnings them- effect, an external threat may act to shut down

selves that become the threat and require one's more mature tendencies to take selfwarding off. Warding off can take various protective action and may take one back to

forms, but a common one is angry skepticism early feeling states when one felt safest if

directed at authorities. This neutralizes the mother and father were interposed between

threat posed by the warning. us and danger.

"Try and Make Me"-Rebelliousness against Partial Compliance: Pacifying by Concession

Mandated Measures As we have seen, in times of threat childhood

In risk literature, it is often said that voluntary themes of goodness, obedience, disobedience,

precautions recommended by authorities are and punishment reemerge. Another manifesseen as more acceptable by the public than are tation of this recurring theme is the tendency

precautions may also mandated measures. Usually, the American to comply with certain pacts of recommended

stir up long-held, Spirit of individual autonomy is cited as the precautions while ignoring other, perhaps

perhaps partially reason for this preference. From what has crucial, parts. What is at work here is an

dormant, beliefs and been said here, mandatory precautions may attempt to demonstrate one's moral goodness

feelings about authority also stir up long-held, perhaps partially through superficial compliance. This "goodand obedience and may dormant, beliefs and feelings about authority ness" can then be used psychologically in one

and obedience and may elicit childish of two closely related ways: to exempt oneself

suitchiish resentment a responses such as resentment and from other tasks (like a child who tells himself

such as resentment and rebelliousness, he has been very good for quite some time

rebelliousness. and is therefore entitled to do as he pleases) or

As young children we learn to deal with the to support an underlying denial. In other

world partially through thousands of warnings words, isolated, circumscribed compliance

we receive from our parents, warnings de- may allow one to say in effect, "I've done

signed to ensure our safety: "Don't play in the almost everything you asked, and now I've

street"; "Never play with matches"; "If I see you earned the right to relax and forget about it"

swing that bat indoors one more time..." For (Wolfenstein 1957).

children, rules of safety are inextricably linked

with rules of obedience. And it is this primi- Pleasing Authorities Rather Than Coping

tive association that is evoked in times of with the Threat

danger, when our more sophisticated, more Partial compliance may spring from other

adult coping skills are threatened. Reinforcing causes as well, but with the same potential for

this regressive tendency is the fact that catastro- harmful outcome. For example, the public

phes are often perceived as punishment or, may put recommended precautions into

perhaps, as divine retribution. effect, but not for the purpose of protecting

themselves from danger as much as to avoid

Reliance on the Protection of censure from authorities. The motivation for

Superior Authorities carrying out protective measures would be

During times of threat, there may be a ten- immaterial but for the fact that this type of

dency to rely passively on the power of ambivalent compliance tends to be superficial 30
and halfhearted. To better appreciate the • Competence (degree of technical expertise in

impact of this ambivalence, we have only to meeting institutional mandate)

recall any recent directive from our supervisor

to perform what we felt to be an unnecessary • Objectivity (lack of biases in information and

task. The task may have been completed, but performance as perceived by others)

certainly not with the same vigor as when we

sincerely believe in a project. • Fairness (acknowledgment and adequate

Cognifive Filters representation of all relevant points of view)

- Consistency (predictability of arguments and

Before people get around to processing the behavior based on past experience and

risk information they have received, and not previous communication efforts)

filtered out via emotional reaction to the Trust in control

threat depicted or to authority per se, they * Sincerity (honesty and openness) institutions can lead to

may still do some cognitive processing of the the implicit acceptance

information about the source of that informa- Trust relies on all five components, but poor of even substantial

tion and the relation between characteristics marks on one attribute may be compensated perceived risk, while

of that source and of the message received, by an excellent reputation or excellent perfor- distrust may lead

This processing may proceed from what seem mance in another dimension. For example, people to oppose

quite unnecessarily cynical assumptions of if objectivity or disinterestedness is impossible actions atopl to that pplse imply risks,

responsible agency officials, but we character- to accomplish, apparent fairness of the mesize it as cognitive because it seems to us to sage and faith in the good intention of the even when those risks

involve the application of logic rather than the source may serve as partial substitutes. Consis- are perceived as small.

following of feelings. We recognize the tency is not always essential in gaining trust,

possibility of disagreement on this point, but persistent inconsistencies destroy the

(Cognitive processing of the information itself common expectations and role models for

is the subject of Chapter IV.) behavioral responses. Trust cannot evolve if

people experience inconsistent responses from

As experience of risk has been replaced by others in identical or even roughly similar

information about risks, and individual situations.

control over risk by institutional risk management, trust in institutional performance has All public institutions have lost trust and

been the major key to risk responses. Trust in credibility over the last few decades except for

control institutions can lead to the implicit the news media (Lipset and Schneider 1983).

acceptance of even substantial perceived risk, Trust and credibility losses are high for the

while distrust may lead people to oppose political system and many government agenactions that imply risks, even when those cies. Science still has a high degree of credibilrisks are perceived as small. ity, although much less than two decades ago.

Since many risk managing agencies have been

Trust can be substructured using the follow- caught in the maelstrom of distrust, it is

ing five perceptual components (Barber 1983; essential to revive the major elements of trust

Lee 1986; Renn and Levine 1991): through performance and communication.

S_ 31
Research shows clearly that there is wide- Respndg to Awciliaiy Charaacristics in

spread agreement in the public as to what Judging Risks

figures are culturally defined as more or less The type of risk involved and its situational

trustworthy (McGuire 1985; Stem and characteristics shape individual risk estimaAronson 1984). For example, when consid- tions and evaluations (Slovic 1987; Renn

ering information presented concerning 1990). Statistical methods have been emtechnological risks, it was the university ployed to explore these qualitative characterisscientist who was seen as far and away the tics of risks. (See also the discussion in

most reliable of sources, because he or she Chapter IV.) The following contextual

was perceived as the disinterested scholar, variables of risk have been found to affect the

uncontaminated by the desire for gain, perceived seriousness of risks (Slovic et al.

committed to truth, and highly qualified in 1981; Vlek and Stallen 1981; Renn 1983;

Low-Probabi)lty high- knowledge and assessment skills. Contrary to Covello 1983; Gould et al. 1988):

consequence risks are that, the industry representative was seen as

usually perceived as the least reliable source of information • The expected number offatalities or losses.

more threatening than concerning technological risk. And for the Although the perceived average number of

more probable risks flip side of the reasons already cited: such fatalities correlates with the perceived

with low or medium persons are perceived as biased in interest, riskiness of a technology or activity, the

consequences. selfishly motivated, willing to dissemble, and relationship is weak and generally explains

without the expertise necessary for competent less than 20 percent of the observed

risk assessment. Clearly, the choice of variance. The major disagreement between

spokesperson, the personification of any technical risk analysis and risk perception is

attempt at risk communication, is one of not on the number of affected persons but

major importance. on the importance of this information for

M xed Fltrs evaluating the seriousness of risk.

- The catastrophic potential. Most people

Some varieties of information filtration show distinctive preferences among choices

processes appear to combine elements of pure with identical expected values (average

emotion and of cognition (more or less logical risk). Low-probability high-consequence

thinking). We identify and single out for brief risks are usually perceived as more threatdiscussion three such processes: ening than more probable risks with low or

medium consequences.

"* Taking account of auxiliary dimensions of

a risk - Situational characteristics. Surveys and

experiments have revealed that perception

"* Attempting to resolve cognitive dissonance of risk is influenced by a series of perceived

properties of the risk source or the risk

"* Responding to the "framing" of the message situation. Among the most influential

rather than to the quantitative information factors are the perception of dread with

it contains respect to the possible consequences, the

32
conviction of having personal control over causes great tension, which forces rapid

the magnitude or probability of the risk, the resolution, most often in the form of deleting or

familiarity with the risk, the perception of modifying points of view until internal consisequitable sharing of both benefits and risks, tency is achieved. Consider, for example, the

and the pot -ntial to blame a person or long-time employee of corporation X, who is

institution responsible for the creation of a informed that the firm is behaving in a way that

risky situation. In addition, equity issues threatens life (dumping toxic materials where it

play a major role in risk perception. The can leach into the groundwater used by the

more risks are seen as unfair for the exposed town for its water supply or storing water

population, the more they are judged as behind an unstable rubble dam or allowing a

severe and unacceptable (Kasperson and lung-destroying dust to accumulate to dangerKasperson 1983; Short 1984). ous levels in the workplace). Our hypothetical

employee almost certainly has some stake in

The beliefs associated with the cause of believing the organization she has devoted her

risk. The perception of risk is often part of life to is good. But she also has a stake in self

an attitude that a person holds about the and community preservation. For that purcause of the risk, that is, a technology, pose our hypothetical person would have to

human activity, or natural event. Attitudes accept that the firm is causing danger, is not

encompass a series of beliefs about the being "good." Something will have to give,

nature, consequences, history, and justifi- and depending on the circumstances it may

ability of a risk cause (Thomas et al. 1980; be either belief in the firm or belief in

Otway and Thomas 1982). Due to the the danger.

tendency to avoid cognitive dissonance (as

discussed below), most people are inclined Resoe to "Framing" of the Risk

to perceive risks as more serious and "Framing" problems arise when the words

threatening if their other beliefs contain used to describe alternatives under uncertainty

negative connotations and vice versa. A are changed-without changing the substance of

person who believes that industry policies the choice-and produce a change in the

are guided entirely by greed is likely to think preferred alternative. A classic example goes as

that the known risks of industrial pollution follows (Kahneman and Tversky 1982).

are only the "tip of an iceberg." On the other

hand, a person who thinks of industry as Imagine that the U.S. is preparing for the

providing consumers with goods and outbreak of a rare Asian disease, which is

services they need and value may well be expected to kill 600 people. Two alternative

inclined to think that concern about such programs to combat the disease have been propollution is overblown, posed Assume that the scientific estimates of

the consequences of the programs are as follows:

Resolving Cogniive D na If Program A is adopted, 200 people will be

"•Cognitive dissonance" (Festinger 1957) is a saved If Program B is adopted, there is a 1/3

term that describes the individual's reaction to probability that 600 people will be saved and a

simultaneously holding two incompatible 2/3 probability that no people will be saved.

points of view. Such a state of internal discord Which of the two programs would you favor?
The majority response to this problem is a Conclusions

risk-averse preference for Program A over

Program B. When the process of taking in information

about risks is presented, with the stress on

Other respondents were presented with the multiple "layers" of filtration, what is perhaps

same problem but a different formulation of remarkable is that we learn anything at all, not

the programs: If Program C is adopted, 400 that some of what we think we have learned is

people will die. If Program D is adopted, less than useful. But this is an extreme,

there is a 1/3 probability that nobody will die pessimistic interpretation. Much of what has

and a 2/3 probability that 600 people will die. been said above applies only to times of great

stress and even then probably only applies to

The majority choice in this problem is risk- a small fraction of the population involved.

seeking: D over C. The certain death of 400 This is true, for example, of most of the denial

people is less acceptable than a 2/3 chance responses. However, we do have to take

that 600 people will die. (pp. 166-67) seriously the observations about the importance of making risk communication clearly

Since A and C are mathematically identical, as relevant to the audience; of choosing an

are B and D, the observed differences in accessible medium and an attractive format; of

choices exhibited in these experiments means not coming on with a parental, authoritarian

that we are not dealing here with purely message; of working to protect competence,

rational thought. Clearly, the choices are at objectivity, fairness, consistency, and sincerleast in part emotional responses to the ity; and of being sensitive to subtleties of

different pictures conjured up by "deaths" and framing (describing) the risk and the

"lives saved." In the first version, the refer- decisions.

ence point or status quo is implicitly 600

deaths, while in the second framing, the We shall return to these and other related

reference point becomes zero deaths. Thus, matters in Chapter VI. But in the next chapin one case respondents are thought to be ter, we turn to a discussion of the cognitive

evaluating "gains" and in the other "losses." problems individuals display when they come

But again, the fundamentals of the given to operate on and make decisions on the basis

problem are explicitly gains, because we are of the filtered information available from the

told that in the absence of any intervention, outside world.

600 lives will be lost. The two interventions

both improve on that base case, at least in

expected value terms.'

4 Kahnenum and Tversky attribute the result to the S-shaped

utility (outcome-weighting) function, which implies risk

seeking for loss gambles and risk aversion for gain gambles.

(See Chapter IV.) But there is also considerable similarity

between this sort of 'framinge problem and the reaction of

subjects to the Allais paradox gambles, also discussed in

Chapter TV. Both seem to involve unacknowledged, and in a 34 logical sense unjustified, shifts in the assumed status quo.
* 9nC idve Problems ith

kM D Desisons

In principle, by suitable design of laboratory lessons for planners and decision makers in

experiments or by careful interpretation of the Corps of Engineers. The approach taken

data from natural experiments, it should be in this chapter will be to use the structure of

possible to probe the following three the rational model to organize a catalog of

cognitive aspects of how nonexpert individu- phenomena that have troubled thinkers in

aý leal with decision making under this field and to discuss:

uncertainty:

- The relation among the phenomena

How they define, estimate, and manipulate

probabilities. (Recall that subjective prob- * The existence of occasionally contradictory

abilities are generally accepted as part of findings

rational decision making.)

• The extent to which the "problems" may

* How they interpret, and especially, how represent entirely rational adaptations to the

they weight the possible outcomes in an complexity and conflicting signals of the

uncertain situation. (Recall that subjective real world (as opposed to evidence of true

"utility" weights are also an accepted part of limitations on the rationality of human

rational decision making.) beings)

* What sorts of decisions they make when The drawing of lessons will be postponed to

confronted with actual choice situations, Chapter VI of this guidebook.

whether in or out of the laboratory.

Problems with Probabilies

Indeed, understanding the cognitive limitations of individuals' use of the normative, In the rational model, individuals are suprational model co; choice under uncertainty posed to either draw their probability inforhas been developing for at least thirty-five mation from objective facts (such as the

years, though examples illustrating those shapes of coins or dice; or records of events

limitations have existed since the eighteenth such as rainfall), or they are supposed to

century. The size and richness of the litera- construct their own probabilities from their

ture in this field poses its own problems-- subjective judgments (such as one might do

how to do it justice; how to make connections by looking at the sky in the morning and

among at least a few of its many dimensions; judging how likely rain is tl~nt day). In either

how to reconcile some of its apparent contra- case, for any but the simplest situations, these

dictions; and how to draw from it practical same individuals should manipulate the

-35
probabilities in ways that are consistent with Updating subjective prior probabilities (or for

some of the fundamental rules of probability that matter, objective prior probabilities)

theory.' using Bayes' theorem can be illustrated with

an example based on one in Parzen (1960) on

Understantd g Indeeden of Events page 119. Assume a district engineer's initial

In the last chapter, we saw that some indi- subjective probability is 0.005 that a particuviduals do not appear to be able to under- lar dam is likely to fail in a given ten-year

stand the independence of events. An period. This estimate would be based on

example almost everyone will have experi- engineering judgment and what is known

enced, either in themselves or others, is a about the dam's site; construction quality;

disinclination to take the independence of history of overtopping, erosion, and leaks;

events seriously. Thus, people are inclined to and other relevant features and/or knowledge ...people am e d attribute memories to dice and coins as an of failures of other similar dams. Further,

attribute memories to outgrowth of a misunderstood version of the suppose that we have available a test that

dice and coins.., law of large numbers. (Some individuals will correctly predicts an imminent failure (failure

argue vigorously that tails must be more likely within ten years), when conditions are right

after heads has come up five or six times in a for that, 95 percent of the time. The test also

row.) Analogously, people often seek comfort correctly gives a dam that has no chance of

or certainty by attributing weather events failing within a decade a clean bill of health

such as floods and tornadoes to some sort of 95 percent of the times it is used in that

extraworldly intelligence or to a cyclical situation. Finally, suppose the hypothetical

process (Kates 1962; White 1964). The dam is tested and the prediction is for failure

general effect of such beliefs is to lower the within ten years. What should be the

subjective probabilities people hold for events engineer's new estimate of the probability that

that have just happened or for events that the dam will fail? Bayes' theorem says that the

have happened frequently relative to some new probability should be:

notion of the long-run mean occurrence rate.

Operationally, the most important manifesta- The prior failure probability times the

tion of this is probably the belief, often widely probability of a positive test given conditions

shared within groups that have experienced a for failure (0.005 x 0.95) divided by the sum:

natural disaster such as a serious flood, that The probability of a positive test given the

a repeat performance "can't" occur for a conditions for failure times the prior subjective

long time. probability offailure plus the probability of a

positive test given that the conditions for

Inaoporating New Information failure do not exist times the prior probability

Another major technical error that has been of no failure (0.95 x 0.005 + 0.05 x 0.995).

observed in handling probabilities is with So the new failure probability should be:

updating in the face of new information. 0.00475 + 0.0545 = 0.087.

Rational individuals who use subjective

probabilities should also use Bayes' theorem 5 Recall, we are talking here about the normative theory. People ought to behave as though they did these things.

to update those probabilities when they are That this is not at all the same as a theory purporting to

explain how they do make decisions is the purport of this

given relevant new information, guidebook.

36
Observe that the test result should cause the they are very good at estimating them in the

engineer to revise his or her initial probability first place (Fischhoff 1988; and Lichtenstein

estimate all the way from 0.005 to 0.087, a et al. 1982). Kahneman, Tversky, and others

multiple of over 17. have discovered that individuals without

special training or expertise tend to overestiThere are at least two problems with lay (and mate the probabilities of very rare events

even expert) behavior vis-A-vis this prescrip- (such as deaths by exotic causes) and undertion. First, Bayes' theorem is simply not well estimate the probabilities of more common

known, and even those who have heard of it, events (Slovic et al. 1982). Even where

and possibly even used it in a statistics class, outside information on probabilities is

are unlikely to have developed any true available, individuals will tend to supply their

familiarity with its operation. Second, its own subjective version in which low-probresults appear to be counterintuitive in many ability events are treated as though more

situations. The reader may find this true for probable, and higher-probability events as less

the example sketched above, where the prior probable than the information supplied

probability estimate is very low and the ability would indicate (Kahneman and Tversky

of the test to detect the condition at issue is 1982). This is shown schematically in Figure

very high. Thus, in the above example, many IV-1. Here "decision weights" may be

lay observers and every professional one thought of as subjective probabilities supplied

might be tempted to say that if such a "good" by the experimental subjects, while "probabiltest gave a warning of failure, we "ought" to ity" refers to objective likelihood estimates for

take it more seriously and revise the probabil- the same phenomena. If the experimental

ity of failure to something closer to 0.95. This subjects were perfect judges of probabilities,

might be called a tendency to overweight the "decision weight" line would coincide

"diagnostic" information, relative to previ- with the 450 line. That is, the estimated

ously held notions.6 decision weights would equal the objective

probability estimates.

Finally, it should be noted that Smith and his

collaborators have found, in a study of the It is not clear whether this phenomenon arises

communication of radon risk, that individuals from a fundamental difficulty in coming to

did process skillfully provided information as grips with numbers such as 10-6, or because

though they were at least approximate very rare events are brought to our attention

Bayesians (Smith et al. 1990). only when they happen, while more common

events bask in relative obscurity. (On reEstimating Subjective Probbi s search into the difference between subjective

Whether people at large can or cannot probability estimates and "true" probabilities,

manipulate probabilities, it does not seem that see Lichtenstein et al. 1982). What is clear is

that if we have reason to doubt people's ability

6 Another way of thinking about the intuition that the new to get the magnitude of probabilities right,

probability-that reflecting the results of the test--ought to

be 095 is as a rejection of the original probability. If, for then it is very hard to work backward from

example, that original estimate had been 50/50 for the fail/

do not fail chances, 0.95 would be the appropriate post-test observed decisions to infer the implied

Dababiity. But even if the original failure probability had

0.25. the appropriate post-tes probability would be weighting pattern for outcomes. This is a

0.864, identif nearly a darn as about large to as fail. the test's ability successfully to -37
subject we take up in the next subsection. situations has to be a fundamental part of

Corps efforts.

From the point of view of the Corps of

Engineers, the problems arising from this The Dominance of Sensational Information

tendency might be of several sorts. For But even this general exhortation makes it

example, the chances of negative conse- necessary to mention a couple of other

quences from very rare events involving phenomena that are sometimes discussed as

failure of Corps facilities, such as levee features of a "probability problem" but may be

overtopping, may be generally overestimated interpreted in other ways as well. In particu-

*by the public. On the other hand, in thinking lar, the tendency of laymen to fasten

about the design of a new facility, that same onto the sensational may not be part of a

public may be unhappy about local participa- cognitive problem. Sensational information

...providing the public tion in the cost of protection against relatively is, almost by definition, very available inforwith good information common occurrences (ice damage to struc- mation. For most purposes in most activities

about probabilities of tures in northern rivers). All these consider- of most ordinary lives, it is not worthwhile for

events of concern...has ations suggest that providing the public with individuals to spend scarce time or money in

to be a fundamental good information about probabilities of events seeking out information on which to base a

part of Corps efforts. of concern in particular planning and decision probability estimate. If something pops up,

Figure IV-I

Decision Weights Related to Probabilities

459 line

Subjective

Decision ......... experimental

Weights rsuts

Probability

Source: Kahneman nd TverskV 1982
ready to hand, it may well make sense to use particular design alternative may produce a

it. If this makes us overestimate the probabil- very wide dispersion of flood damages

ity of being murdered by devil-worshipping avoided compared to the no-project case.

cultists, it is probably not a problem for Thus, one quite improbable event involving x

anyone. But if it makes many people overesti- inches of rain in 24 hours, which would have

mate the chances of overtopping of a levee, caused huge losses before the project, might

then we do have a collective problem. successfully be controlled, implying equally

huge benefits. But an event of only slightly

The Role of ExpertJudgments lower probability and slightly higher rainfall

In the matter of expert judgment and its role might overtop all the planned defenses and

in subjective probability formation, we have cause about the same damages as in the

to keep in mind that citizens of modem, free without project situation, i.e., might imply

democracies hear constantly from experts zero benefits (damages avoided). in such a

who disagree about everything under the sun: situation, the decision maker(s) might well

whether a little drinking is good for you or think that another dollar of benefits added by

not; whether paper or Styrofoam cups are a project refinement when benefits are already

easier on the environment; whether an high (perhaps involving investment in

interest rate cut by the Federal Reserve Board recreational facilities) is worth less than

is currently desirable; whether we should try another dollar of damage prevention in the

to introduce a greater element of parental overtopping case (perhaps simply by an

choice into public education. What has to be increase in emergency spillway capacity).

clear to the observer of this cacophony is that,

for every issue, one of the sets of contesting Utility Fwwutios

experts is wrong. The trick is knowing who Economists usually refer to weighting functhey are in advance. In the absence of costly tions as "utility" functions, and we may

(in time and money) investigations of who is distinguish between functions (or weighting

most likely to be right in any given situation, schemes) that reflect aversion to "risk" and

rules of thumb such as "split the difference" or those that reflect a positive seeking out of

"a plague on all their houses" can certainly not "risk." Here "risk" may be thought of as the

be ruled irrational. dispersion of outcomes (e.g., their variance or

standard deviation.)

Problems with Weighting

Outcomes in Uncer•an Siftuti Risk aversion is equivalent to the feeling

described above that the "value" of another

In Chapter II, we discussed the possibility that dollar of benefits is smaller, the higher the

in some situations, particularly those involv- benefits are--the value of losses is larger, the

ing widely dispersed uncertain outcomes, larger the losses (see Figure IV-2). It is

individuals may rationally want to apply important to understand that these functions

nonlinear weighting schemes to the outcomes of whatever shape need not remain academic

in addition to taking account of probabilities, abstractions. It has been demonstrated in

For example, if the design decision at issue practical decision problems that it is possible

involves a flood control problem, any through skillful questioning to construct such

-9
Figure IV-2

Utility Function Shapes and Their Characterization

(a) (b)

Utility Utility

Risk Neutral

Outcome Outcome

(c) (d)

Utility Utility

Risk Averse

for Gains

Zt~~~isk 

frGn

Pronen

Loss Gain Outcome

Outcome Risk Prone

for Losses

40,,
a weighting function for an individual over seem to be widely neglected by consumers

the range of outcomes faced in the decisio,: to (Kunreuther and Slovic 1978).

be made (Benjamin and Comell 1970).

Observe also, that in trying to infer subjective

Other than our expectation that anything weighting schemes from actions, we run into

called "utility" ought to increase as the an identification problem of sorts. If we

underlying outcomes improve, however, we believe that individuals take any account of

cannot judge the "correctness" of patterns both outcomes and (subjective) probabilities,

displayed in actual situations by lay or expert we cannot disentangle the "cause" of observed

individuals. But it is usually hypothesized decisions. For example, an individual could

that most people in most situations in their have risk averse preferences but still buy

daily lives are risk averse. This pattern of lottery tickets if that individual systematically

utility weight is consistent with the purchase overestimated the chance of winning the

of insurance at a premium exceeding the grand prize. (And such systematic overestimaexpected value of the loss from the insured- tion is what "feeling lucky" is all about.)

against event. It is not consistent with

purchasing lottery tickets at prices above the Problems with Observed Judgments

expected value of the winnings. That behav- in Risky Situations

ior bespeaks risk-seeking preferences.

The last subsection referred to certain patterns

E ne about Utility FunctioU s of decision that have been observed in the

There is, however, some evidence (Kahneman debate about cognitive limits on individuals'

and Tversky 1982) that, at least in laboratory ability to deal with uncertainty. These

settings, individuals use utility-weighting patterns include the purchase of insurance at

schemes that are risk averse for gains and risk premiums exceeding the expected value of the

seeking for losses, certaiply an odd, though losses and the purchase of lottery tickets at

not an irrational, pattern. If this pattern were prices above the expected value of the

widespread, we would commonly not see winnings. It was pointed out that such

insurance purchased against catastrophic actions are not evidence of inability to cope

losses, but neither would we see much activity with risk. It is almost always difficult to say,

in the lottery (or numbers) business. Thus, outside a laboratory setting, what they are

the fact that we do see lines outside of stores evidence of, since subjective weights and

selling state loLtery tickets when the prizes probability estimates may reasonably be

become very large, and that we see people thought to interact in the decision process.

buying at least some kind of insurance

suggests that the laboratory results may not be Within laboratory settings researchers can

terribly good guides to reality. Admittedly, better control the information and incentives

the insurance purchases are generally required that lie behind decisions under risk. And in

as conditions for obtaining a mortgage or such settings, or in closely related survey

registering a car. Newer forms of insurance, research, there is evidence of actual logical

often not required, such as flood insurance do failures in individuals' risk-related decision

41
processes. We shall consider three kinds of (mixes of probabilities and outcomes) they do

problems that research has discovered: not focus only on the differences but also take

account of the similarities. The following way

"The paradoxes, exemplified by the "Allais of visualizing the paradox is attributed to

paradox" in which revealed decisions Robin Dawes (Pool 1981). Imagine an urn

violate a fundamental axiom of the rational filled with 100 balls, divided as follows: 89

model red balls, 10 blue balls, and 1 black ball.

Now imagine that four different games of

" "Preference reversal" in which stated chance (referred to here as "lotteries") have

preferences over generalized "lottery tickets" been created based on this urn. In each

(explained below) contradict the relative lottery, the payoff obtained by the player is

prices for which the subjects would be determined by which color ball is drawn from

willing to sell the same "tickets" the urn. In the experiments, the subjects are

each asked to make two choices: between

" "Risk ratings" in which subjective ratings of lotteries A and B and between C and D, where

activities, both individual and collective, the payoffs for each lottery are as described in

have been shown to be highly imperfectly Table IV- 1.

related to the actual risk of death posed by

the activities7 Logically, the only difference between the two

choices is the result of drawing a red ball. In

The AMlis Paradox both A and B a red ball gets you a million

The "Allais paradox" involves a combination dollars; in both C and D it gets you nothing.

of logic and empiricism demonstrating that Therefore, the independence axiom requires

individuals faced with uncertain, lottery-type that someone who prefers A to B also prefers

decisions, violate what is known as the C to D and vice versa. But empirically there is

"independence axiom." That is, when a very widespread, if not unanimous, choice

individuals choose between two lotteries of A over B and D over C.

Table IV-1

Payoff Matrix

Outcomes

Ball Drawn A vs. B C vs. D

Red $106 $106 0 0

Blue $106 $2.5 x 106 $106 $2.5 x 106

Black $106 0 $106 0

7 "Framing problems" that crop up in this same literature

have been classified in this guidebook a.v part of the filtration

42 process and were discussed in Chapter III.
One can tell stories that explain this behavior, with handling choice under uncertainly that

such as invoking the notion that the prospect go beyond difficulties with probabilities and

of the certain $1 million in A produces a new odd subjective utility patterns.

status quo. Then, Lhe choice between A and B

is interpreted as a choice between a 10/11 Preference Reversal

probability of adding $1.5 million and a 1/11 "Preference reversal" is said to occur when

probability of "losing" the $1 million that is contradictory answers are given to two

notionally in hand. In the C vs. D choice different questions concerning choices among

there is no change in status quo accepted a single set of alternative "lottery tickets."

implicitly, so the (unlikely) zero event is not Again, a classic example should help make

translated into a loss. But story or no story, clear how the reversal arises and what it

the real situation does not involve a change in means. Grether and Plott (1979) provide a

the status quo, and the commonly observed simple graphic one in their important paper

choices are irrational. They bespeak problems on this phenomenon.'

Figure IV-3

Dart Board Patterns for the Preference Reversal Experiment

The "P" Game The "D" Game

8 Grether and Plott also report on the rather large psychology literature-even up to that date--that had explored this

phenomenon.

43
Imagine that you can choose between playing judgments. They also designed the pattern of

two games, P and D, with darts (see Figure payoffs so that increasing wealth as the experiIV-3). In P, the dart board is a circle with a ment proceeded would not be a potentially

single radial line. A dart is thrown by a distorting factor.) Further, they attempted to

blindfolded person (with nonetheless a control for a set of competing noneconomic

guarantee that it will hit the interior of the theories of decision making under risk with the

circle). If it hits on the radial line, you will aim of ruling out as many of these as possible.

receive nothing. If it hits anywhere else, you In this latter regard they could not in the end

will receive $4. (Clearly this is a near certain rule out one possibility related to a previously

$4.) The alternative board, D, is divided into discussed problem, the effect of framing. That

two areas by a pair of radial lines. One area, is, they could not rule out the possibility that

covering say 40 percent of the circle, will decision makers seize on "anchoring' informaproduce a $16 payoff if the dart hits it. The tion such as probabilities in one case and

60 percent area produces a zero payoff if hit. payoffs in another for reasons that have little to

do with the quantitative substance of the

The subjects who are presented with these two gambles in question, but more to do with the

games are asked to say which one they would language and context of the experiment (or real

prefer to play and to assign a money value to decision). If true, it becomes very difficult to

each, usually thought of as the price for which understand in any general way what people

they would sell the right to play the game if think they are doing when they make uncerthey held it. Consistently over actual experi- tain choices. Even more disturbing is the

ments, a large proportion of those presented prospect that once some understanding was

such problems say they prefer the P game but developed, manipulation would, in principle,

assign a higher value to the D game. become extremely easy.

As in the previous two examples, we see a There is, however, another side to the literature

clear problem with the logic (or rather the on preference reversal, albeit a strain that

illogic) that must lie behind this contradic- remains to date obscure because unpublished.

tion. It comes down to this. If you prefer P to The principal source of this other side is Peter

D you ought to require being paid a higher Bohm at Stockholm University, and his

price to give up P if you owned the right to contribution has been to move the experimenplay it than you would require to give up D if tation out of the laboratory and to increase by a

you owned the right to play it. factor of several hundred the significance of the

payoffs involved in the P and D games. In

Grether and Plott, in their own preference Bohm's first experiment, the P and D "lotteries"

reversal experiments, worked very hard to were defined by used cars. The subjects were

eliminate any conditions that might allow the university graduate students who were in the

reversal phenomenon to be argued away as market for a car. From the subjects who chose

rational (e.g., they tried to make the gamble to participate, Bohm extracted rankings of the

payoffs large enough so that they could assert cars as well as stated willingness-to-sell prices.

that serious efforts were being made by the He found no preference reversals (Bohm

experimental subjects to make correct 1990). In another nonlaboratory experiment, 44
this one involving real-world lottery tickets, differences. In general, lay people tend to

Bohm and a collaborator found that 11 underestimate the riskiness of such very risky

percent of the subjects exhibited preference activities as smoking, drinking, and driving,

reversal, a considerably smaller percent than while they overestimate the riskiness of such

has been found in the laboratory exercises exotic activities as mountain climbing and

(Bohm and Lind 1991). This suggests that common "threats" such as vaccinations (Slovic

the laboratory results may actually include an et al. 1980).

element of minimizing decision costs in the

face of rather trivial rewards despite the efforts It appears from the literature that has grown

of experimenters. This, in turn, suggests we from this subject that the key to understandshould be doing additional research before ing the observations is the notion that far from

using preference reversal evidence as part of being cognitively limited (though they may be

an argument for the widespread existence of information limited), lay people strive to work ...individuals regularly

serious cognitive problems in individuals' with a very complicated model when they pursue voluntary

ability to deal with uncertainty, decide what risks to be concerned about. Lay activities that are much

people think about a number of dimensions riskier to themselves

Estimates of Relate Riskiness of the decisions or activities they are asked than are the collective

Estimates of "relative riskiness" of individual about (Slovic et al. 1980). For example, one activities they often

and collective activities have been of consider- study asked lay people to say how concerned object to on the

able interest since people began pointing out they were about 90 different activities and

that individuals regularly pursue voluntary then to rank the 90 activities or sources of risk

activities that are much riskier to themselves (threats to lives) along eighteen dimensions as

than are the collective activities they often summarized in Table IV-2. Subsequent

object to on the grounds of riskiness (Starr statistical analysis led the researchers to

1969). Viewed as an apparent disconnection conclude that the eighteen dimensions could

between acceptable, self-imposed, and what have been represented by three factors that

we call collectively suffered risk, this phenom- determine the level of concern about (the

enon seems to hint at another bit of evidence perceived riskiness of) an activity. The first of

of cognitive difficulty in dealing with risk, for these they labeled "dread," for it reflects such

it shouldn't make any difference how the one- considerations as whether the activity is

in-one-thousand chance of dying comes controllable, whether it could be globally

about. It might be argued that this phenom- catastrophic, whether its effects would persist

enon is a sort of large-scale Allais paradox, in the future, and whether exposure is

where the independence axiom is violated by voluntary or involuntary. The second they

otherwise presumably rational people. label, "familiarity," and it reflects such considerations as whether or not the activity is

Whether one is willing to go that far or not, it observable, known to the exposed persons,

has certainly been the case that studies known to science, and produces immediate

comparing the riskiness perceptions of lay effects. The third factor measures extent of

people and experts have turned up substantial exposed population. The sorts of results they

obtained are shown schematically in Figure

9 Riskiness is usually expressed in terms of deaths-numbers IV-4. Activities that score high on factor I (to

of deaths per year in the U.S. population caused by, or

probability of a randomly chosen individual's dying from, 45
11aI,)e IV-2

t-lement'i of- a Survey ol RiAk Pirrceptlon

A. The Haatr&'!I Rnhed:

1, Home Amfura e;4 31 (oloting Al fltvi

2 Home appltan e; 12 sooi tuirin (1) Motphiric

I.Homne power 1to)Ik 33 "odiumrt witalf 61 ( );10i1 Iatplv'

4 Miknrwdw ven% 34 FVwod prewrvaliw;,! 64 Valhtin

5. I'owe~r mowri 1¶3 k--(X itr~iadton 6') Antuibiot it

6s H~andguni; 36 1lani oil~t "ItIble 0 1)"t Prcipt ;;ili

7 TertorIAni 17 )[mic vxl~otauiti A7 Mlxmg

A, Crimte 3M ;1;( oi~w (1 fowiihull "ýItntg

4. Nerve gm;3. Abeiw;o; OQ Virvwol;V

10. Nuclevir weofio 40, Police wot4 70 Ut'NOW)

11. Nationaol dolenw 41, Vieighting 71 ituriung 12. V'arf are 42 (IhrlItn;aý live hlu~,h; 72 logging

13. M~cydp'; 43. (I0qtie~k 71 Moiuin ,Ittribhning

14 Mitorcytie; 44, I'luoromenvtii ght-, 74, Mui;;roorn I huting IS, motor Vehicle's 4'¶ Hait dye;ý 7) IRek reA onial boal ing

to, RA~lroAd 46 (,'hemical d infe antit; 7A R~oller i-oot';

1 7. Corenerl Aviation 47 DNA researth 77 ImuhA divirig 1$ ss¶,1 48. llqud natutal gm; 7A ')ýuerd;x

19, JUMbo) Jets 49 Smoking 70 I'ibathirig 20. Commerdal aviation ¶30. iractor; 80I "'rung Ž1. Anesthetic-3 ¶1 (-'hemical I ~rillizer;4 At 'witnmin g pools

22. Voicnaion ¶2. Herbiodes 82. bitoI Ole(tvit Power

23. Pregnancy, birth ¶33. 1)11 AI llydroekectri power

24. Open-heart surgery ¶34. Perticide;5 84, 'olat electric power

23. surgery ¶33, Aspirin $' on' la power

20. RAd lotion therapy ¶36. Marijuana 86 Ntrteair rower

27. tDiagriosic Croy'i ¶37. Heroin 87. flytngit

28. Alcoholic beverage's 38. 1.aet rile 89. sk'54y;Iper; 29. Caffeine 139. Amphetamine4 89 RI~rdge% 30. Wooer fluoridation 60. lý riuae W0 tOAn

8. The dimensions on which they were ranIhed:

1. Is hzard accepted voluritarilyý

2. is the tisk of devith immediate?

3. To what extent are rislk; known to pron;tv expoied?

4. To what extent are r1;kF, known to soenice)

5. is this tisk new and novel (it old and familIAr)

n, D)oes the rtik have a chronic or a c:atastrophic eflie 0

7. Howe people learnied to live with thi; hozard or i; it dreadedW

8. How likely Is; A mi~hap to cgu~e death . Can mi,.haps he preventiedl

10. It a mls;hap occurs, c:an the damage be controlled)

11. How many People'are expoged to Ihi% hazard)

12 N~e4 the hazord threatent future generation;) 113 Are you personally at ri~k from tht; hazard?

14.Are Zh berteliti equit;Ably diwriblied Among thowe At rlik?

11 ¶3lioei the hazaird threan glbl-t~rpe

16. Are the dAmage-producing procev;es ob,;rrvahle A; they (h ýuv

1 7 Are the. ri~; Incr-eamng or de-reaminA7

18, Coin the risk; he reduced eamily)

416 .. --souwo Paul slovic, ilardkh PTi4hhofl, oind soroh L"t hloil~qoin 1080, lip 1$1 1 A
Figure IV-4

Rankings of Hazards: A Few Examples

Unknown/Unfamiliar

Food Coloring Lasers

Nuclear

Cosmetics *Power

Christmas Tree Lights Pesticides

Common & Dreaded

accepted * Dams

Nuclear

Weapons

Bicycles Commercial Terrorism.

* * Aviation

Crime e

Alcoholic

Beverages * Firefighting

Known/Familiar

Source: Slovic et al. 1980, p. 201 47
The question is, What does all this mean? • They often exhibit or rather appear to work

That lay people misperceive "risk"? Or do from utility-weighting schemes that would

they understand a richer notion of "risk" than lead toward very nonconservative behavior,

is captured by probabilities of death (or though in other settings they seem to favor

average fatalities per year in a given popula- explicitly conservation options.

tion)? The latter is probably the case, a

finding with profound implications for • They are prone to inconsistency and even

communication about collective risks between blatantly irrational decisions in the face of

responsible public agencies and concerned real, albeit, not familiar or weighty choices.

populations.

On the other side, it must be acknowledged

We turn, in the next chapter to another that:

Lay people have a veryr source of problems with individual and

rich notion of collective decisions in risky situations. This * Generally, being good at probability

"rskiness," one takes the discussion to the collective or social estimation is probably not very important

involving many level, describing some of the special problems to success or even survival of individuals.

dimensions other than that arise because our ultimate interest is in

probabilities of death managing risks to groups, not in how indi- - Spectacular events are easy to learn about.

for exposed viduals think about gambles over alternative The commonplace, beyond that in our own

populations. used cars. lives, must be sought out.

CoKclsios - Subjective utility-weighting patterns

U can and, in general, should look different

Once individuals have attended to and filtered for different outcome ranges. Laboraexternal information concerning risky deci- tory experiments can only cover a tiny

sions, they are in a position to process what part of the range people see in everyhas survived. The literature on risk percep- day life.

tion and the actual behavior of people in the

face of uncertainty-whether the task be The restricted range of laboratory experiguessing at probabilities or choosing among ments involving actual rewards and the

alternative "gambles"-compares that evi- hypothetical nature of questions probing

dence of such processing to the benchmark of such apparent contradictions as the Allais

the normative model set out in Chapter I1. In paradox may very well imply that much of

general, the conclusions of that literature find the observed intentions and behavior

individuals wanting. In summary: represent minimum effort at decision

making.

"* They neither judge nor manipulate probabilities correctly. Lay people have a very rich notion of

"riskiness," one involving many dimensions

"* They seize on spectacular information and other than probabilities of death for exdismiss the judgments of experts. posed populations.

48
Social Pressure and Amplification

In Chapter II (Figure 11-3 and the accompany- these studies exclude from the analysis

ing text) we chose to portray external social the social and cultural variance of risk

pressures on individuals as influencing the interpretations.

processes of filtration and cognition. This

kept our schematic "model" fairly tidy and Sociological analysis provides some further

helped us to organize our discussion. But the insights into the social and organizational

reader should be warned that although two factors that influence risk perception (May

decades of research have created a substantial 1989; Clark 1989). Some studies attempt to

base for understanding how people perceive identify social influences in the formation and

and respond to risk, we lack a comprehensive change of attitudes toward risk-bearing

concept of the social experience of risk, that activities or technologies (Short 1984, 1989;

is, the social processing of uncertainty and the Gould et al. 1988). Some aspects, such as

perception and evaluation of expected perceived fairness in the distribution of risks

consequences related to an event or activity and benefits, have gained special attention as

(Luhmann 1990). The social science ap- part of the dynamic interaction among the

proaches to risks constitute a patchwork of various groups involved in rejecting or

many different schools and perspectives, legitimizing a proposed imposition of a

risk on a special population (Kasperson and

As discussed in Chapters II, III, and IV, Kasperson 1983; MacLean 1986; Rayner and

psychological research into risk perception Cantor 1987). More theoretically oriented

has revealed that contextual factors shape studies have emphasized the social construcindividual risk estimations and evaluations tion of risk interpretations and their affinity

(Slovic 1987; Renn 1990). The identification to different types of knowledge acquisition,

of these factors, such as voluntariness, social interests, and cultural values

personal ability to influence risks, familiarity (Bradbury 1989).

with the hazard, and the catastrophic potential provides useful information about the These sociological studies have been valuable

elements that individuals process for con- for understanding the variability of risk

structing their interpretation of risks. In interpretations among different groups and

addition, analyses of people's heuristics in for pointing out the organizational problems

making inferences have shed some light on that aggravate the potential outcomes of risks

how risk information is generalized and due to institutional constraints that impede

evaluated intuitively (Kahneman and Tversky effective risk management and control (Short

1979). These psychological studies fail to 1984; Freudenburg 1988). However, they

explain, however, why individuals select remain scattered and often fragmented and

certain characteristics of risks and ignore fail to link scientific assessments, individual

others. More broadly, by focusing only on perceptions, and the social and cultural

the individual as an information processor, experience of risk. 49
Coherence and plausibility are characteristics as part of the political process

of the cultural approach to risk developed by

such thinkers as Douglas, Rayner, Schwarz, * The social amplification of risk

Thompson, and Wildavsky (Douglas and

Wildavsky 1982; Rayner 1987; Schwarz and General Cultural Background

Thompson 1990). According to this approach, cultural beliefs and world views "Scientific coping style" refers to the tendency

determine how people experience and of professionals who study risk response to

interpret risk. This notion is intrinsically deal with the world in a very particular way:

plausible because we recognize that a substan- one that involves the use of rationality to deal

tial part of who we are-how we view the with problems and to overcome obstacles,

world; how we think about and interpret and one that involves taming unknown

what we experience; how we see our respon- phenomena by systematically achieving

world views determine sibilities to our fellow humans; and so on-is understanding of the principles by which

how people experience determined by our socialization within a these phenomena operate (Fenichel 1939).

and interpret risk. particular society. As children, we learn from This tendency, rooted as it is in the scientific

our parents, older siblings, and other adults method, is certainly not all bad. In fact,

what is expected of us in most normal it is arguably the springboard of Western

U situations in life. We also learn the habit, to a civilization.

greater or lesser extent, of checking our

feelings, deductions, actions, and reactions What may be problematic is that as a personal

with those of others. This generally shared coping method this scientific style may lead to

habit is what leads to substantial coherence important blind spots about human functionwithin society in matters such as how we ing, about one's own responses as well as

generally view natural hazards and how we those of others. Thus, for example, it has led

respond to a particular and immediate threat risk managers to view their analysis of risk as

to life or limb. an objective lens through which reality is

brought into clear focus and to assume that

We consider social learning and interaction this scientific coping style is universal. As we

under four broad headings in roughly have seen, those with a less scientific bent

increasing order of narrowness of focus: (i.e., the public), when faced with dangerous,

unknown forces, may react in irrational

"* General cultural background and world ways that in the extreme do not serve ecoview nomic gain, physical safety, or even value

maintenance.

"* More specific groupings of individuals

within our culture based on their attitudes Very roughly speaking, what this says to

toward hierarchy, procedural rules, and planners and decision makers in agencies

cohesiveness such as the Corps of Engineers is that even if

it could be pointed out to the members of the

"* Political considerations and the potential for public that their information filters were

manipulation of risks and risk information arbitrary or too efficient; even if they could be

501
chided each time a faulty probability estimate like the government to refrain from extensive

were made or manipulation completed; even regulation or risk management efforts. Tii,,

if evidence of irrationality could be pointed group contrasts most with the egalitarian

out to them, they might very well not care. If group, which emphasizes cooperation and

the coping style they learned valued emotion equality rather than competition and freedom.

rather than logic, the "normative" model Egalitarians focus on long-term effects of

would be a curiosity, not an ideal. In short, human activities and are more likely to

providing facts about the issue or decision at abandon an activity (even if they perceive it as

hand may not help. The only option open for beneficial to them) than to take chances.

engendering dialogue may be a more funda- They are particularly concerned about equity.

mental discussion of why even a minimal The third group, the bureaucrats, relies on

notion of protecting ourselves must involve us rules and procedures to cope with uncerwith some version of the normative model. tainty. As long as risks are managed by a

capable institution and coping strategies have

Cultural Group Affiliations been provided for all eventualities, there is no

need to worry about risks. Bureaucrats

In recent years, anthropologists and cultural believe in the effectiveness of organizational

sociologists have investigated the social skills and practices and regard a problem as

response to risk and have identified four or solved when a procedure to deal with its

five patterns of value clusters that separate institutional management is in place. The

different cultural groups from each other fourth group, the atomized or stratified

(Schwarz and Thompson 1980). These individuals, are either part of a hierarchy or

different groups have formed specific posi- believe in hierarchy, but they do not identify

tions on risk topics and have developed with the hierarchy to which they belong.

corresponding attitudes and strategies. They These people trust only themselves, are often

differ in the degree of group cohesiveness (the confused about risk issues, and are likely to

extent to which someone finds identity in a take high risks for themselves but oppose any

social group) and in the degree of "grid" (the risk that they feel is imposed on them. At the

extent to which someone accepts and respects same time, however, they see life as a lottery

a formal system of hierarchy and procedural and are often unable to link harm to a

rules). concrete cause (Thompson 1980).

According to this literature, there are four The practical utility of these insights would be

major groups in modem society that are likely greater if it could be anticipated that memberto enter the risk arena: the entrepreneurs, the ship in the groups were distributed systematiegalitarians, the bureaucrats, and the stratified cally, for example, with respect to region or

individuals. Members of the entrepreneurial risk management setting. Then planners and

group are convinced that risk taking provides decision makers could take advantage of what

them with opportunities to succeed in a is understood about group assumptions and

competitive market and to pursue their reactions when structuring a program of risk

personal goals (Rayner 1987, p. 13). They are communication. In the absence of such

less concerned about equity issues and would convenient systematic patterns, it is probably

51
safe to assume the distribution of group Actors will enter the risk arena if they expect

membership to be random across regions and this will provide them with an opportunity to

decision areas. Then recognition of the gain more resources (Kitschelt 1986; Dietz et

existence of such groups just sensitizes the al. 1989). Beyond their reservoir of resources

risk communicator to some of the possibilities at any time, they can gain more resources by

for foul-ups. exchanging one resource for another (e.g.,

winning public trust by sharing power

Risk in the Political Arena through participation or exchanging evidence

for prestige) and by communicating to other

Beyond the problem of distrust in risk actors and the media. The objective of

management institutions, risk debates take communication is to receive public support

place in a political context in which risk and to mobilize other groups for one's own

reduction may only be one objective among cause. The more resources a group can

uncertainty of risk others. Using the metaphor of a sporting mobilize in an arena, the more likely it is that

assessments provides arena, social conflicts can be described as it dominates the conflict resolution process

sufficient flexibility to struggles between various players, controlled and gets its point of view incorporated in the

"-support" conflicting by a rule enforcement agency (usually a final decision.

evidence and claiis, govemmental institution) and observed by

professional reporters (the media) who Actors may use the arena to gain more

Sinterpret the actions on the stage and transmit resources even when the topic of the arena is

their stories to a larger audience (Lowi 1967; not of central importance to them. They can

O'Riordan 1983). use risk as a vehicle to get their message

across and to mobilize public support. Risks

To be successful in a social arena, it is neces- are then linked with other topics such as

sary to mobilize social resources. These business ethics, consumerism, or lifestyle

resources can be used to gain the attention changes. These linkages may or may not

and support of the general public, to influence reflect logical connections; they can be based

the arena rules, and to "score" in the arena in on associations or plausibility. They are

competition with the other actors. Social constructed by social groups as a means to

resources include money, power, social mobilize resources.

influence, value commitment, and evidence.

Money provides incentives (or compensation) The inherent uncertainty of risk assessments

for gaining support. Power is the legally provides sufficient flexibility to "support"

attributed right to impose a decision on conflicting evidence and claims. Because of

others. Social influence produces a social the weak position of the rule-enforcement

commitment to find support through solidar- agencies, risk arenas tend to experience more

ity. Value commitment induces support rule innovations than other arenas in which

through persuasion and trust, while evidence strong enforcement agencies are present. In

can be used to convince persons about the arenas with high ambiguity of the political

likely consequences of their own actions. issue, weak status of the rule-enforcement

Resources are not only the ends but also the agency, and a lack of immediate personal

means to accomplish other goals. experience about the potential consequences

52
of political decisions, the distribution of including significant indirect impacts such as

resources relies almost entirely on the success liability, insurance costs, loss of confidence in

of one's communication efforts. institutions, or alienation from community

affairs. Such secondary effects often trigger

In general, then, the Corps of Engineers can at demands for additional institutional responses

the very least expect that its own risk commu- and protective actions or, conversely (in the

nication efforts will not constitute the only case of risk attenuation), place impediments

game in town, whenever there is a high- (or in the path of needed protective actions. In

even moderate) stakes decision on the line, accordance with the metaphor of amplificaThe Corps has to be prepared to be attacked tion in the processing of electronic signals,

for its assumptions, methods, conclusions, "amplification" includes both intensifying and

and its motives for all of the above. How it attenuating signals about risk. Thus, alleged

responds to such a critique may prove at least overreaction of target audiences receives the

as important as the style and content of its same attention as alleged "downplaying." look to others to

primary message in determining the outcome determine what his

of what, at that point, will have become a The amplification process starts with either a reaction to threat

contest or controversy, not just an issue. physical event (such as an accident) or the should be.

recognition of an adverse effect (such as the

Social oIIs discovery of the ozone hole.) In both cases,

SAmplfi of Risk individuals or groups will select specific

characteristics of these events or aspects of the

An individual will often look to others to studies and interpret them according to their

determine what his reaction to threat should perceptions and mental schemes. These

be. The group may serve to alert the unsus- interpretations are formed into a message and

pecting individual to danger or to give false communicated to other individuals and

reassurance to each of its members, because groups. Upon receiving the messages, these

everyone is looking to other members for cues social groups or individuals process the

regarding danger (Begum and Ahmen 1986; information and may feel compelled to

Lamm 1988). This prosaic but fundamental respond. Some may change their previously

observation may help to motivate the more held beliefs, some may gain additional

complex notion of the social amplification of knowledge, some may be motivated to take

risk as proposed in 1988 by Kasperson and actions, and others may use the opportunity

his colleagues (Kasperson et al. 1988). to compose a new message that they will send

to the original sources or other interested

This concept of social amplification is based parties (Renn 1991).

on the thesis that events pertaining to hazards

interact with psychological, social, institu- Individuals or groups collect and respond to

tional, and cultural events and shape risk information about risks and act as "amplificabehavior. Behavioral patterns, in turn, tion stations" through behavioral responses or

generate secondary social or economic communication. Amplification stations can

consequences that extend far beyond direct be individuals, groups, or institutions. It is

harms to human health or the environment, obvious that social groups or institutions can

53
amplify signals or consequences only via the perception studies, then, can contribute to

actions of individuals working in those social improving risk policies in several ways

aggregates. But individuals in groups and (Fischhoff 1985):

institutions do not act or react predominantly

in their role as private persons but, rather, • They can identify and explain public

according to the role specification associated concerns associated with the risk source.

with their positions. Amplification during

reception may therefore differ among indi- • They can explain the context of the

viduals in their roles as private citizens and in risk-taking situation.

their roles as employees or members of social

groups and public institutions. Amplification • They can identify cultural meanings and

occurs on the communication (signals) and associations linked with special risk areas.

consequence level (behavioral responses).

resolution of conflict in - Based on this knowledge, they can help to

democratic societies is The social amplification framework provides articulate objectives of risk policies, in

achieved by initiating an integrative concept. The distinction addition to risk reduction, such as fairness,

discussion among the between individual and social amplification procedural equity, vulnerability, and

major parties stations corresponds with the two traditions institutional trust.

olvedin t in risk perception: the individual processing

of information ard the social responses to risk - They can provide a foundation for the

based on experience of (dis)trust, the political design of procedures or policies to incorpoprocess... arena conditions, and cultural affiliations. It rate these cultural values into the decision

provides a more holistic picture of the risk making process.

perception process and takes into account

psychological, sociological, and cultural They can help responsible agencies design

aspects. programs for evaluating risk management

performance and organizational structures

Concusio for monitoring and controlling risks.

Although risk perceptions differ considerably There is no impartial referee available to judge

among social and cultural groups, the integra- the appropriateness of risk perceptions.

tion of beliefs related to risk, the cause of risk, Science may help to determine the magnitude

and its circumstances, into a consistent belief of the risk, but the only viable resolution of

system appear to be common characteristics conflict in democratic societies is achieved by

of public risk perception in almost all coun- initiating discussion among the major parties

tries in which such studies have been per- involved in the decision-making process or

formed (Renn 1989). These perceptions affected by the decision outcomes (Habermas

reflect the real concerns of people and include 1971). Such a dialogue can be organized in

the undesirable effects that the technical the form of advisory committees, citizens

analyses of risk often miss. Social risk panels, formal hearings, or in other ways

(Fiorino 1989).

54
Guidelines for Risk

Communication

Framework The characteristics of the four elements of

the risk communication process are deterThere are four elements of the risk commu- mined by the audience being addressed.

nication process that need to be considered There are two very different audiences that

by the planner: the planner has to communicate with: (1)

Corps and governmental (federal, state, and

Objective(s), that is, what is the risk local) decision makers and (2) the genieral

U issue? Who constitutes the audience? publc. Planners must tailor the communiWhy is the communication being cation techniques to the particular group

undertaken? they are dealing with at the time. There are

distinct differences in how risks are preContents of the message, that is, what sented to each group.

* information is to be conveyed in

order to accomplish the objectives? The presentation of risk to decision makers

is similar, yet different from the presentaForm of communication, that is, how tion to the public. The basis for this

should the message be transmitted divergence is the different role each group

from the source to the receiver? plays in the planning process, leading to a

variation in the content and form of the risk

Feedback from the audience, that is, communication between the two audiences.

what is being received? The difference between the two groups can

be summarized as follows: decision makers

The objectives depend on the problem or may require a greater level of detail in their

environmental hazard at hand. Two broad information about the risk of the project

alternative objectives are (1) the planner than is needed by the public. The content

may want to provide the audience with a and form of the risk communication with

better understanding of the risk and these groups reflects these differences.

uncertainties surrounding planning alternatives and thus to stimulate cogent and The type of data provided to the decision

informed discussion-and u0imately a makers by the planner reflects the nature of

defensible resolution, or (2) the planner the decision maker's job. In order to make

may desire to communicate risk in order to informed decisions about risk, information

encourage appropriate behavior by indi- such as advanced statistical analysis is used

viduals and communities. Undoubtedly by the planner to develop alternatives for

there are other objectives, the consideration of decision makers.

55
Examples of technical data are the prob- essential and that is to check what is

abilities and associated probability distribu- actually getting through to the intended

tions of the various risks. The same level of audience, through soliciting feedback.

detail is not generally needed for communication with the public. The public's ability The specifics of content, form and feedto understand and analyze the detailed back, and the guidelines suggested here for

information used by decision makers, such dealing with those elements of the process

as statistical analysis, is usually limited, differ significantly depending on the

Therefore, it is important that the appropri- objective of the exercise. The key considerate content and format of communicating ations in design of form are common to

risk be used when addressing the public, both objectives. Thus, for example, when

Feedback is essential These concepts are discussed in detail in the objective is to influence understanding,

this chapter. it is especially important that the content of

the risk communication message come to

communication The manner in which information is grips with the cognitive problems identified

programs 1 every actually communicated between the in Chapter II. For example, care must be

setting. The presence planner and the audience is another taken in the expression of probabilities and

of risk raises the ante. difference in the communication process. in the framing of the decision conseThe most manageable Information flowing from the planner to the quences. On the other hand, when action

and e a wy t decision maker is usually transmitted in the is the desired objective, the contents of the

obtain feedback i to form of written documents such as Corps message must be sensitive to the factors that

reconnaissance and feasibility reports, and motivate individuals to take actions (as

convene one or more internal meetings. The public is usually discussed in Chapter III) and must deal

focus groups. given information through town or neigh- explicitly with the actions desired. In other

borhood meetings, television and radio words, tell them what you want them to do,

Uspots, newspaper advertisements, and why you want them to do it, and how

brochures. The reconnaissance and feasi- should they go about doing it. This apbility reports used by decision makers are proach is equally suited for an audience of

available for the public to read. However, internal or external decision makers as well

these types of reports tend to be technical as the public in general.

in nature and more difficult for the general

public to understand. In the interest of In designing a format for the communicaconveying the risks and the options avail- tion, however, far more commonality exists

able to deal with the risks, it is usually best between the objectives. Thus, a message

for the planner to describe the situation in should always be vivid and personalized,

nontechnical terms. concise and concrete. Whenever possible it

should be delivered in person to small

The contents and form of the message are groups and should be reinforced by an

both important and distinguishable. Thus, authoritative local figure.

it is helpful to think about risk communication in terms of "what you tell them" and Feedback is essential to successful commu-

"how you tell them." One other element is nication programs in every setting. The

56
presence of risk raises the ante. The most implications of probabilities of uncertain

manageable and economical way to obtain events.'1 When understanding in a planning

feedback is to convene one or more focus context is at stake, it is prudent to:

groups. Such groups allow in-depth discussion of issues and problems in a Express uncertainty in a variety of ways

nonthreatening setting and, while not while avoiding modes of expression that

producing statistically representative encourage or seem to confirm beliefs in

information, can nonetheless alert the the cyclicity or supernatural purpose of

program manager to needed adjustments in natural events.

strategy and tactics. But what the focus

groups can most usefully probe varies with For example, in order to breathe life into the

the objective. In a program aimed at notion that the probability of a flood on a

enhancing understanding of a risky deci- particular river at a particular place in a usflt has tho

sion setting, the cognitive threats to under- particular year is 0.01, it has been thought

standing have to be the first concern. In a useful to say that the "return frequency" of "return frequency" of

program aimed at stimulating action in the such a flood is 100 years. The problem with such a flood is 100

face of risk, the perceptions of the commu- this otherwise obvious transformation is that years. The problem ...

nity as they relate to desirability, fairness, it gives ammunition to the brain's disinclina- is that it gives ammuniand seriousness of purpose must be gauged. tion to think in terms of independent events. tion to the brain's

If such a flood occurs in year t, the brain dinclnaion to think

U would like to say that now we will not have to in terms of independent

worry about that again for t plus one hundred

years, well beyond our lifetime. This is not a events.

General Guidelines on Risk very useful view of the natural world.

Communication Content n

An alternative is to dream up physical analoIn this section, ten guidelines for the gies to the 0.01 probability. Philosophers, for

content of risk communication are set out example, like to talk about pistols that have t

and discussed, five for each of the objec- chambers and one bullet, and the exercise is

tives: understanding and action. These are thought of as Russian roulette with that pistol.

summarized in Table VI- 1. An alternative might be a wheel of fortune on

a carnival midway or something involving

colored Ping-Pong balls in jars. The key point

When Understandng Is the Objective is to make it clear that the pistol cylinder or

the wheel of fortune is spun, or a drawing is

Perceiving Natural Processes and made from the jar every year and that the

Probabilities same probabilities apply every time."

As we have noted, there is substantial evidence (and most of us can probably testify 10 E-g., on probabilities of natural hazards-Kates 1962. White

1964; on using new information to update existing estimates- through personal experience) that it is Tversky and Kahneman 1980; and making estimates of probabilities,

common for people to have trouble estim?' especially of rare events-Slovic et al. 1982; Lichtenstein. et al. 1982;

ing, manipulating, and understanding the IThe pistol figure breaks down in the multiple year context as soon

as we have a flood (bullet) because there is no tomorrow in failed 57

Russian roulette.
Table VI-1

Principles And Guidelines for

Risk Communication: A Schematic

Objectives Understanding in the Planning Action in the Management

Context Context

Content Express uncertainty in several Emphasize seriousness but not

ways but in general avoid feeding powerlessness.

into problems with independence.

(e.g.: don't use recurrence intervals.)

Give ranges of probabilities and Reinforce socially responsible

outcome measures whenever behavior.

experts differ.

Frame the decision problem in Affirm possibility of mitigating

different ways; at least as gains impacts through desired action.

relative to worst case and as losses

relative to best case.

Stress analogy of project to Stress equity of sacrifice being

insurance wherever applicable, requested.

Provide relative risk information Publicize model behavior by

in a schematic way. respected local citizens where possible.

Format * Make message vivid.

"* Use authoritative source.

"* Make message clear, concise and concrete.

"* Personalize the message.

"• Deliver the message in person to small groups.

"* Multiple messages should contain common theme.

Feedback Use Focus Groups - Probe:

" For cyclical or supernatural views * Perceived relative desirability of

of natural-world uncertainty alternative possible actions

" For presence of risk-prone • Perceived actions by others in

utility patterns over losses community

" Meaning of expressed preferences • Effectiveness of monitoring and

for particular decisions, using enforcement regime, if any

willingness-to-pay format

• Regressive behavior

58
Acknowledging Differences in problems once the first has been accepted.

Expert Opinion This is because much expert analysis and

Although much of the Corps planning work prediction about the natural environment is

does inevitably involve uncertainty, one of the expressed in certain, rather than uncertain,

most common sources of that uncertainty is terms. Thus, each expert is likely to say, "This

hydrology, an area in which historical records will happen." You will seldom hear, "This

and well-tested methods leave little room for will happen with probability one-half, that

differences of expert opinion. Whenever with probability one-quarter, and something

Corps decisions involve some other quite different from either with probability

environmental variables, however, such one-quarter." In this sort of situation, the easy

differences are almost inevitable, reflecting the way out is to report the range of predictions

tenuous state of our ecological knowledge. and leave the audience to deal with that range ...ask a dozen experts

Thus, ask a dozen experts how tinkering with as it will. More difficult, but also more

how tinker/ing with a

a particular wetland will affect downstream productive for the long-run continuing

water quality or populations of particular dialogue the Corps must have with its citizen particular wetland will

plant or animal species, and you are liable to clients, is to use the techniques developed by affect downstream

get at least half that many answers. decision analysts to discover the subjective water quality..., and you

probability estimates that the experts hold but are liable to get at least

The temptations in such a situation are, first, do not usually express. A somewhat less half that many answers.

not to ask more than one expert, and that one satisfactory, but still useful, exercise, if those

being a person with whom the planner has involved locally will not play the game, is to

had experience and, second, when other bring in an independent expert to make the

opinions do come to light, to try to keep them probability judgments.

out of the public discussion. The downside of

this strategy is that it feeds, in a remarkably To understand how this might work, consider

efficient way, the latent (or not so latent) an entirely hypothetical example and a subset

mistrust that some citizens may harbor for the of the sort of questions an analyst (A) might

Corps. ask an expert subject (E). (This example is

adapted from material in Raiffa, 1970). For

Therefore: consistency with the next example, we shall

use the example of the proposed flooding of a

Risk communication should acknowledge and locally important wetland. It is downstream

report on differences in expert opinion with from a developed residential area (including a

regard to the outcomes to be expected from golf course) and upstream of a substantial

proposed actions. Every effort should be length of stream that is used for recreation

made to express the range of opinion in and drinking water. This flooding could

symmetric terms and to use the language of occur because increasing emphasis on flatrisk and uncertainty, water recreation within the reservoir just

below the wetland makes it desirable to raise

If the first part of this principle seems to cut the level of water maintained on average

against the grain for professional engineers, behind the dam.

the second part may pose even greater

59
One question of interest to the public might function, smoothed and used in calculations if

be, What will happen to the level of nutrients desired.

in the stream below the reservoir? (Nutrients

would affect both the recreational and water- Framing the Outcomes from Alternative

supply uses of the stream. Recreation value Projects or Policies

would be reduced if an increased nutrient We know from experimental social psycholload led to algal blooms, periodic oxygen ogy that there is a good chance people will

reduction, and loss of ability to support game respond differently to two versions of a

fish. Water supply costs could increase mathematically identical choice, if one is

because of the health threat believed to be expressed as gains and the other as losses

posed by nitrates in drinking water.) Because (Kahneman and Tversky 1982). Accordingly,

the nutrient sequestration function of wet- it is worthwhile, when possible, to:

lands is not precisely understood and modeled, there will probably be a range of answers Express the outcomes from contemplated

to this question-let's say that range runs alternatives both as losses from a best case

from zero increase to a doubling on average, and as gains from a worst case, explicitly

with no one certain about the outcome. In pointing out that the two formulations are

such a situation, A would ask E questions of identical.

the form:

Following this principle will not always be

Give me a value for the increase in easy, but to illustrate what is involved, let us

nutrient concentrations such that it would follow up on the simple example introduced

be extremely hard for you to make up above. Assume an office of the Corps is

your mind to choose an answer above or considering an increase in the frequency of

below it; that is, a value such that you higher water levels in a reservoir with the aim

think it as likely that the increase will of improving summer recreation availability.

prove to be above it as it is likely to be The results will include the gain of 50 recrebelow it. ation days; the flooding of a productive

wetland, which in turn could lead to local loss

Once such a value has been obtained, call it of wetland plants (perhaps half the total

N*. A then goes on to press E to subdivide number of plants species present in the

the intervals above and below N* into equally reservoir area); gain of 100 acres of prime

likely subintervals. (That is, E is asked to largemouth bass fishing; loss of nutrient

divide 0 to N* and N* to 2 by numbers N** sequestration and doubling of nitrogen and

and N* * * such that phosphorus loads in the stream below the

P( < N <N) =P(N** < N <N) = P < N <N***) reservoir. To summarize, the best and worst

= N*** < N < 2.0) = 0.25 outcomes are presented in Table VI-2. Other

dimensions such as cost and outputs of

This process may be repeated as long as E will peaking power or flood control would in

stand for it and as long as the problem setting general have to be included. But they would

seems to justify it. The result can be shown as only clutter - iluminating in the

a density histogram or as a distribution example. Usia ,. and worst benchmarks,

60
Table VI-2

Best and Worst Outcomes

Best Outcomes Worst Outcomes

50 days of recreation gained No gain in recreation days

No plant species lost One-half of species lost

100 acres of bass fishing gained No gain in bass fishing

No deterioration in water quality Doubling of nutrient loads

downstream

Table VI-3

Outcome Information

Increase Frequency of Leave Levels as They Are

High Water Levels

Losses from No loss of recreation days Loss of 50 recreation days

best case due to low water levels

One-half species lost No loss of species

No loss of fishing Loss of 100 acres of fishing

Doubling of nutrient loads No water-quality

downstream deterioration downstream

Gains from Gain of 50 recreation days No gain from worst case

worst case

No gain from worst case One-half of species saved

100 acres of fishing created No gain from worst case (no

fishing created)

No gain from worst case Nutrient loads one-half of

worst case

61
the planner could then provide outcome in question may be seen as premiums on a

information along the following lines (though policy, and how both premium and the

not necessarily in the following format) as outcome being insured against would affect

shown in Table VI-3. individuals and communities. This suggestion is made for two reasons. First, the

The point of the exercise is that individuals in cognitive-problems literature surveyed in

the audience will probably be creating their Chapter IV suggests that in laboratory

own best- and worst-case benchmarks and experiments and surveys, where no real gains

may respond differently to the same proposal, or losses are at stake, individuals exhibit riskdepending on which base they focus on. prone or risk-seeking utility patterns over

Giving them a range of ways of thinking losses (Kahneman and Tversky 1982). (This

Perhaps the most about the choice may help them to see more means that these individuals would refuse to

effective way of clearly which way their interests lie. The purchase insurance unless the premium

effort is more likely to be worthwhile the charged was even lower than the expected

more emotionally loaded the elements of the value of the loss being insured against). outcome. Human deaths (or lives "saved") are Second, the actual nature of insurance

insurance aspect of a probably the most loaded and "mere" dollars arrangements with which individuals are

situation is through a the least. familiar from daily life has been distorted

distribution that away from protection against catastrophic loss

attaches probabilities to Understanding the Insurance Analogy and into a prepayment plan for routine bills.

outcomes... In some, though by no means all, Corps Accordingly:

planning, an element of insurance purchase is

implicit. For example, flood control projects Whenever large losses are possible, whether in Ushift the probability distributions over losses the absence of or because of Corps actions or

of human lives and over damages to struc- decisions, an effort should be made to

tures and their contents. The annualized communicate the variance or at least the

costs of the structures involved may be seen range of outcomes in addition to what is said

as the premiums for the shifts. Similarly, about expected outcomes.

municipal water supply projects shift the

probability distributions for the receiving It is our contention that in the face of the

utilities of their capacities to deliver water prospect of real losses of a catastrophic

under different rainfall (or lack of rainfall) nature--the best example for the Corps being

events. These shifts, in turn, change the losses from urban flooding-risk averse

probability distributions of losses suffered by preferences are more likely than risk seeking.

customers when restrictions have to be But so long as communications stress eximposed in order to save water to prevent pected values, the range of outcomes remains

much greater losses later, if the drought event buried. Perhaps the most effective way of

continues. presenting information emphasizing the

insurance aspect of a situation is through a

The audience for risk communication in such distribution that attaches probabilities to

situations may need to be reminded why outcomes (dollars, lives lost, etc.). An

insurance exists, how the costs of the project example of how comparative distributions can

62
be used to present this kind of information is concentrate on the probability-of-death

shown in Figure VI-1 (histograms can also be dimension. Second, lay people often seem to

useful visual aids). An alternative tabular view as relatively safe common, but rather

presentation of the same material is shown in dangerous activities, such as smoking or

Table VI-4. The project benefits distribution drinking and driving, while perceiving such

in Table VI-4 is estimated based upon exotic activities as mountain climbing and

sampling from the with and without project such quite safe, but much less familiar

EAD distributions in Figure VI- 1. actions, as being vaccinated, as very risky

(Slovic et al. 1980). An individual's risk

Setting the Risk in Perspective perception is also influenced by personal

Our survey of the literature on how lay people experience. For example, if a person had the

deal with risk included some observations on experience of actually being in a flood, their

the evidence concerning common problems short-term perception of flood risk may be

with the lay ranking of the "riskiness" (a different from someone who had never

multidimensional notion) of many activities experienced a flood. The person who was a

and situations. Two of those observations are flood victim in the past may perceive a flood

especially pertinent here. First, lay people to be more damaging or deadly than it really

and experts commonly differ on their assess- is. Accordingly, we suggest the following

ments of riskiness. This is quite possibly principle:

because lay people, though often lacking

complete information, are working with Whenever a planning or decision problem

complicated models of what constitutes involves potential loss of life, provide a context

riskiness. Experts, on the other hand, tend to for the problem-specific information in the

Figure VI-I

Expected Annual Damage and Benefit Distributions

17.5-

15-- ...... With Project

12.5 -Without Project

Frequency 10- (%)

7.5 -

5

2.5-

0I I I I I I I I

0 2 4 6 8 10 12 14 16 18 20

Annual Damages

($1,000,000) 63
TABLE VI-4

Expected Annual Damage (EAD) and Benefit Distributions

(Millions of Dollars)

EAD Without Project EAD With Project Project Benefits

Mean 5.501 2.658 2.843

Minimum 0.755 0.297 0

Maximum 16.924 8.154 14.580

Range 16.168 7.857 14.580

Standard Deviation 2.479 1.056 2.417

Source: Greeley-Polhemus Group, Inc. (1992b), pages FC-45 to FC-47.

Figure VI-2

Estimated Versus Actual Ranking of Risk

Esthwnamow dei deof pet yew

100,000 --

- -r.W Ac.toda . •-

10,000 HoIiet"di-m.

_O ""10 C

1,000 - lo

I 1 I I ' Io 

1 10 100 1,000 10,000 100,000 1,000,000

AchuMl numfer of daUw per yew

Source: Starr and Whipple 1980.

64-.
Table VI-5

Risks That Increase Chance of Death by 0.000001

Smoking 1.4 cigarettes Cancer, heart disease

Drinking 1/2 liter of wine Cirrhosis of the liver

Spending 1 hour in a coal mine Black lung disease

Spending 3 hours in a coal mine Accident

Living 2 days in New York or Boston Air pollution

Travelling 6 minutes by canoe Accident

Travelling 10 miles by bicycle Accident

Travelling 300 miles by car Accident

Flying 1,000 miles by jet Accident

Flying 6,000 miles by jet Cancer caused by cosmic radiation

Living 2 months in Denver on vacation from N.Y. Cancer caused by cosmic radiation

Living 2 months in average stone or brick building Cancer caused by natural radioactivity

One chest X-ray taken in a good hospital Cancer caused by radiation

Living 2 months with a cigarette smoker Cancer, heart disease

Eating 40 tablespoons of peanut butter Liver cancer caused by aflatoxin B

Drinking Miami drinking water for I year Cancer caused by chloroform

Drinking 30 12 oz. cans of diet soda Cancer caused by saccharin

Living 5 years at site boundary of a

typical nuclear power plant in the open Cancer caused by radiation

Drinking 1,000 24 oz. soft drinks

from recently banned plastic bottles Cancer from acrylonitrile monomer

Living 20 years near PVC plant Cancer caused by vinyl chloride

(1976 standard)

Living 150 years within 20 miles of

a nuclear power plant Cancer caused by radiation

Eating 100 charcoal broiled steaks Cancer from benzopyrene

Risk of accident by living within 5 miles

of a nuclear reactor for 50 years Cancer caused by radiation

'(1 part in 1 million)

Source: This table is taken from "Analyzing the Daily Risks of Life" by Richard Wilson,

reprinted with permission from Technology Review, copyright 1979, vol. 81, no. 4

(February 1979), pp. 41-46, and extracted from Glickman and Gough (1990).

65
form of expert-based relative risk information replenish a full soil moisture regime. The

for many human activities and natural events, belief about the seriousness of water shortage

is often stated as a necessary condition for

It is important to point out that following this persuading consumers to conserve.

principle does not prejudge the issue of what

determines risk acceptability. For example, it In one of the early studies of consumers'

does appear that lay people perceive activities behaviors related to the environment, White

to be less risky if there seems to be some (1966) concluded that people who believed

individual control present (driving drunk), the drought of the mid-1960s was serious

M and if it is possible to have had some experi- were likely to adopt more conservation

ence with the behavior without having activities and use less water on a daily per

...it does appear that lay suffered (smoking). Publishing a relative risk capita basis than those who believed it was

people perceive comparison is unlikely to change this. But, at not serious. The same relationship between

activities to be less the very least, it can help the audience to see the belief that shortages exist and that water

where the imposed risk under discussion conservation is necessary was investigated by risky if there seems to

seems to fit in the scheme of things. Ex- Bruvold (1979) in a survey of 900 consumers

amples of such comparisons are given here as in nine water supply districts of the San

control present... Figure VI-2 and Table VI-5. Francisco Bay area. His results showed that

an index measuring the perceived seriousness

M When Action Is the Objective of the 1976-77 California drought by each

survey respondent was the best predictor of

Perceived Seriousness of the Risk personal conservation effort. Also, in a survey

The implication of past research relevant to of 195 residential consumers in Goleta,

this factor can be stated as follows: California (Talarowski and McClintock 1978),

the respondents who used more water than

People will make an effort to react positively their district-imposed allotments perceived

if they believe that a genuine risk exists in the California drought as less serious than did

their community. other respondents. Some other risk qualities

that make a difference in people's judgements

This attitude-behavior relationship was are shown in Table VI-6.

observed as a result of surveys conducted

during and after major episodes of resource These results seem to be replicated in survey

shortage (both water and energy). Consum- research in the area of energy conservation.

ers must sense a high level of personal risk For example, Thompson and McTavish

and discomforting uncertainty about an (1976) found that about 20 percent of

impending drought to take personal action to respondents believed in present or future

avoid undesirable consequences. The stim- energy shortages; it was these individuals who

ulus may be descriptive accounts and pictures reported practicing significantly more conserof the last drought in the same geographic vation measures than the respondents who

area showing inconveniences as well as did not hold such beliefs. Similar studies can

monetary impacts. Hydrologically, it can be be conducted by Corps planners to assess

shown that short-term rainfall is inadequate to public perceptions of the seriousness of the
Table VI-6

Qualitative Factors Affecting

Risk Perception and Evaluation

Conditions Associated Conditions Associated

with Increased Public with Decreased Public

Factors Concern Concern

Catastrophic Fatalities and injuries Fatalities and injuries potential groupecd ia time and scattered and random

space

Familiarity Unfamiliar Familiar

Understanding Mechanisms or process Mechanisms or process

not understood understood

Controllability Uncontrollable Controllable

(personal)

Voluntariness of Involuntary Voluntary

exposure

Effects on children Children specifically Children not

at risk specifically at risk

Effects manifestation Delayed effects Immediate effects

Effects on future Risk to future No risk to future

generations generations generations

Victim identity Identifiable victims Statistical victims

Dread Effects dreaded Effects not dreaded

Trust in institutions Lack of trust in Trust in responsible

responsible institutions institutions

Media attention Much media attention Little media attention

Accident history Major and sometimes No major or minor

minor accidents accidents

Equity Inequitable distribution Equitable distribution

of risks and benefits of risks and benefits

Benefits Unclear benefits Clear benefits

Reversibility Effects irreversible Effects reversible

Origin Caused by human actions Caused by acts of

or failures nature or God

NOTE: In selecting risks to be compared, it is helpful to keep these distinctions in mind.

Risk comparisons that ignore these distinctions (e.g., comparing voluntary to involuntary risks) are likely to backfire unless appropriate qualifications are made.

Source: Covello et al. 1988 and extracted from National Research Council, National

Academy Press 1989.

67
risk and follow with education programs when self-interested behavior, the greater the number

the perception falls short of the true magnitude of people who adopt this course of action

of the risk. If people are made aware of the (Kelley and Grzelak 1972; Talarowski 1977).

risk, they will make an effort to react with However, certain conditions have been shown

positive action to reduce that risk. to influence consumers' willingness to further

group welfare. Dawes, McTavish, and Shaklee

Perceived Interest of the Group (1977) noted that co-operative response

The potential for conflict between group dominated over self-interest when individuals

interest and individual interest arises when were allowed to communicate freely about the

some publicly supplied resource is scarce. commons dilemma.

Facing the rapid depletion of a necessary

The idividua's belies resource, the individual may choose to act The individual's beliefs about the attitudes of

about the attitudes of selfishly, either in ignorance of, or disregard others in the group also strongly feature in

others in the group also for, the ultimately undesirable long-term behavior patterns. The incentive for engaging

strongly consequences of his or her behavior. Such a in seif-interest in a laboratory commons

problem is often characterized as the "tragedy dilemma as opposed to group-interest stems

behavior patterns. of the commons" (Hardin 1968) or a "social from the belief that other group members

trap" (Platt 1973). It refers to a situation when would behave in a similar fashion (Dawes,

* property rights provide an incentive for McTavish, and Shaklee 1977).

overexploitation or rapid depletion of a

resource. When informed about the risks and It must be remembered that laboratory simulaconsequences of ecological disruption and tions of commons dilemmas cannot account for

wildlife displacement, sensitivity may mold a the numerous complexities that surround

group consciousness that overrides individual reality. The issue of a dilemma in the real

self-interests, world may be a very gradual process. Furthermore, other constraints in the real-world

Studies by Talarowski (1977), Marwell and situation, such as factors governing awareness

Ames (1979), and Stem (1976) demonstrate and response habits, can influence consumer

that: behavior (Berk et al. 1981).

Educating and informing people about the Perceived Efficacy of Risk Reduction Efforts

undesirable long-term consequences of self- Several studies of behavior point to a general

interested choices will be effective in cultivating finding that can be stated as follows:

strong group interest and moral concerns in the

community. An individual's belief that his/her personal effort

will matter in reducing risk will increase his/her

Self-interest is a more powerful determinant of likelihood of adopting risk reduction measures.

behavior than group interest, and this deduction has been confirmed by laboratory experi- This relationship seems to be in agreement

ments on the commons dilemma. Proponents with the theory of fear arousal, which states

of this belief have concluded that, in general, that the belief in the efficacy of a coping

the greater the incentive for pursuing response in avoiding a negative event is one of 68
the most important determinants of behavior fate or luck. Those regions where residents felt

(Rogers 1975). that what they do affects their futures incurred

Hamilton (1985) compared self-reported and a significantly lower death rate.

actual water savings for 471 households during

a conservation campaign in Concord, New When the public believes that their personal

Hampshire. The findings indicated that the efforts will meaningfully contribute to reduced

knowledge of respondents' own water use was risk, they will be more likely to take action to

relatively low; however, the accuracy of self- adopt risk reduction measures.

reports showed an increase with the extent of

conservation behavior. This result may be General Guidelines for Risk

interpreted in terms of perceived efficacy of Communication Form

conservation efforts. Consumers are more When the public

likely to engage in conservation efforts if they The theory of persuasive communication and believes that their

know how much water they can save by doing past research suggests several important personal efforts will

so. This, in turn, may convince them of the requirements in designing maximally effective mefuontril

importance of their personal efforts in- iessening messages, whether the objective is to induce mea ully ribute

the impacts of drought. understanding or action. These requirements

are discussed below, will be more likely to

The perception of the efficacy of personal take action to adopt risk

efforts is also linked to a personality trait The Message Must Be Vivid and Personal reduction measures.

known as "locus of control" (Rotter 1966). Webster's dictionary defines the adjective

Locus of control is the sense of the extent to "vivid" as "full of vigor and freshness of the

which individuals believe they can have an immediate experience evoking lifelike images

influence on their lives. Thus, persons with an within the mind." Therefore, a vivid message

"internal locus" believe that what they do that clearly portrays the risk can be described

themselves matters; those with an "external as lively, sharp, and intense. Several studies

locus" believe that forces external to them- have shown that people assign disproportionselves, such as fate or luck, direct their futures. ate weight to information that is very vivid

Persons characterized as internally oriented (Borgida and Nisbett 1977; Yates and Aronson

have been found to be more efficient in 1983).

gathering and utilizing information relevant to

solving environmental problems (Sims et al. A local news reporter shown on the evening

1982). By contrast, persons believing that news while walkimn along the edge of an

external forces control their fate and environ- emergency levee ,ý C the water has already

mental events are more likely to regard per- encroached above the sandbags placed only

sonal risk reduction efforts as having little, if hours earlier is much more effective in perany, effect in alleviating the consequences of a suading individuals to take both short and

natural hazard. This division of personality long-term action to protect property and life

characteristics was exemplified by their study from floodwaters than statistical reports

of deaths attributed to tornadoes. Higher rates detailing the abnormally high accumulation of

of fatalities were found in geographic regions rainfall in the distant mountains. This type of a

where people believed they were controlled by vivid example presented by individuals who

69
are familiar to the community is often needed regulatory agency used less electricity than

to effectively persuade residents to take action. did households receiving identical pamphlets

believed to be distributed by the local electric

The Message Should Originate from a Person utility company. Utilities are often perceived

Information received from another person, as not being trustworthy (Costanzo et al.

especially a respected friend or a colleague, is 1986).

likely to have a greater impact on the decision

making of the person receiving the message Even when seen as being trustworthy, water

than impersonal information summaries. Such utilities can endanger their credibility by

summaries, although based on highly repre- "crying wolf' and asking for unnecessary

sentative statistical studies and conveying more water conservation measures. For example,

The more personal the accurate and efficient information, often exert in 1983 the Salt River Project in Arizona was

information, the higher less impact than less representative but more in the middle of a long-term water conservae likehd tht it vivid and personal accounts. In the earlier tion campaign when large rains in the nearby

will be perceived ad example of a river rising above emergency mountainous areas called for adjustments in

riprap and sandbags, the local news reporter reservoir operations and the release of

delivered the message, and the magnitude of approximately 200,000 acre-feet of water to

receiver. the risk was absorbed by everyone watching the usually dry Salt River (Mee 1985). This

the telecast. Detailed hydrological studies most likely ruined the credibility of the Salt

I prepared by credible researchers with historical River Project conservation Drogram and those

data and the best probability estimates would of local water providers who were also

have less impact on the public than the news requiring water conservation.

reporter. The reporter's account will weigh

much more heavily in the resident's Credibility problems can be overcome by

imagination than those of a team of unknown strictly monitoring information sources in the

researchers summarized in stream flow studies. community and by making available the

We have little doubt that it will be quite resources and skills of the water utilities to

decisive in the example. nonprofit and neighborhood groups not

involved with conflicts of interest (Stem and

The Message Must Come from a Credible Aronson 1984). Any type of positive involveSource ment in the community also has a potential of

Consumers will react to a message only if it is enhancing credibility.

perceived as emanating from a credible source.

Research shows that the credibility of the The Message Should Be Clearly Applicable

source greatly influences the effectiveness of to the Person Receiving It

the message (McGuire 1985). Messages from The information should be sufficiently specific

noncredible sources produce a lesser change in to the person's particular situation (Planning

attitudes than do messages attributed to a and Management Consultants 1983). The

highly credible source (Costanzo et al. 1986). more personal the information, the higher the

Craig and McCann (1978) found that house- likelihood that it will be perceived and

holds receiving pamphlets on energy conserva- processed by its receiver.

tion thought to be distributed by the state

70
A letter from a mayor to all property owners depends greatly on their specificity (Stem and

detailing a proposed Corps of Engineers Gardner 1981). Messages like "Turn off the

reservoir project provides an example of water while brushing your teeth" are likely to

specific personal information. In the letter, be more effective than exhortations like

the mayor explains why the project is desir- "Conserve water!" or some vague prompts like

able for both the community and for the "Don't be a drip!" or "Be water wise!"

individual. Construction of the reservoir will

allow for a controlled flow of water, reducing Concise message. Messages have to be brief

both the risk of flooding and the areas and free from all unnecessary elaborations

susceptible to flooding. This type of informa- and superfluous detail. Reading a wordy

tion makes the letter recipients aware of how brochure or newspaper advertisement may

the project will be in their best interest, easily become too tiresome a task. Every effort should be

Request for project support in such a letter made to reduce

may be significantly more effective in achiev- Concrete message. Borgida and Nisbett (1977) ambiguity of the

ing support for the project than a generalized tested impacts of abstract and concrete

advertising campaign. information among undergraduate students message. It must

and found out that most people regard so- dearly articulate the

The Message Must Be Clear, Specific, called base year data (i.e., statistical summa- purpose of the commuConcise, and Concrete ries of population) as if they were uni- nication and the actions

Both the theory of learning and the theory of nformative. Apparently this kind of infor- requested from the

communication indicate that clear, specific, mation lacks impact because of its abstract, person receiving the

concise, and concrete information is remem- insipid nature. information.

bered best (Ester and Winett 1982).

Multiple Messages Should Contain a

Clear message. The message should be easily Common Theme

understood, free from obscurity and Since most public education and information

ambiguity. Every effort should be made to campaigns use multiple means of communireduce ambiguity of the message. It must cation (e.g., mail, billboards, newspaper

clearly articulate the purpose of the communi- inserts, radio, or TV messages), a campaign

cation and the actions requested from the should iw -oduce a common theme in the

person receiving the information. For form of a logo or a slogan.

example, a statement such as "If you do not

leave your house immediately, the floodwa- The purpose of such a theme line is twofold:

ters will close your last escape route," is clear,

while "It is advisable for people to leave their • It permits fragmentation of the campaign

homes because of the floodwaters," is not into a number of specific messages delivclear as to the impending danger confronting ered at different points in time, all messages

the residents. containing the same theme.

Specific message. Psychological research on • It depicts the strategy of the entire cam-

"prompts" designed to evoke a desired paign. For example, "Beat the Peak" was

behavior shows that their effectiveness used as a theme line that captured the

71
strategy of the conservation program aimed Check for the presence of patterns of utility

at reducing peak water demand in Tucson, weights that would point toward incautious

Arizona. policy prescriptions. Perhaps the largest

concern here is the possibility of risk seeking

Guidelines for Seeking Risk when losses are at stake.

Communicaion Feedbak

Check for the possibility of internal confuAs already argued in the introduction to this sion such as that evidenced by the preference

chapter, we recommend that a systematic effort reversal phenomenon. This will probably

to obtain feedback be part of every risk com- involve asking preference questions two

munication exercise. The most efficient way to ways: one using strictly preference terminoldo this seems to be to convene one or more ogy; the other using the willingness-to-pay

focus groups composed of members of the format developed in the contingent valuation

intended audience (Stewart and Shamdasani literature (Mitchell and Carson 1989).

1990). What such a group or groups should

be used to explore will vary with the objective When Action Is the Objective

of the communication exercise. In this area we have somewhat more experience, primarily because the effects of weatherWhen Understanng Is the Objective related hazards are often mitigated through

While the principles developed above for the voluntary action by citizens, and the volunteer

content of risk communication attempt to an- campaigns have been studied and refined over

ticipate and deal with specific problems the years. Examples of events that are conduidentified in the literature, our understanding cive to the voluntary actions of citizens include

of these matters is growing steadily, but suc- shoring up a levee with sandbags to prevent

cess can by no means be guaranteed. Accord- flooding and a door-to-door campaign to warn

ingly, it is well to check on the progress (or people of approaching or impending danger

lack of it) being made. The following is a such as a flood, brush fire, or hurricane.

minimal checklist. Nonetheless, it is still wise to seek feedback on

the key issues. The following four items are

Check for the audience's interpretation of particularly crucial:

probabilities in the case at hand. This may

involve pretesting physical analogy models, - Check to make sure that the actions being

such as the wheel of fortune, for definitional touted in the campaign are perceived as

fitness. Another question is whether the effective in mitigating the threat.

notion of independence is getting across or

requires reinforcement. A third general - Check that the audience sees the goal of the

problem area to be explored is the possibility campaign and the manner of its application

that the audience contains a significant and enforcement as fair and effective. (e.g., is

number of people who subscribe to some one group, neighborhood, or town seen as

sort of causal or ethical theory of the events carrying the load for others because of some

in question that interferes with their ability to extraneous factor that makes them/it easy to

think of them as random. take on or easy to monitor.)

72
* Check that the seriousness of the threat has threats to life and limb) of the contemplated

not been so emphasized that significant project relative to other activities and

amounts of regressive behavior have begun programs, both individual and collective.

to show up.

When the Objective Is Action

Summary * The campaign should effectively convey a

message about the seriousness of the risk.

Social-behavioral research reviewed here This effort should not, however, be allowed

provides a number of guiding principles for to degenerate into a scare campaign, for the

designing a risk communication program that behavior triggered by fear is likely to be

addresses a given risk issue. Further illustra- counterproductive.

tive examples can be found in the supplement

at the conclusion of this chapter. The program should provide social reinforcement of risk reduction behavior

The guiding principles, which pertain to the especially at the local level. This will

content of the risk information program, can cultivate strong group interest and moral

be summarized as follows, commitments within the community.

When Understanding Is the Objective • The campaign should make an attempt to

" Uncertainty should be expressed in a convince the consumers that their actions

variety of ways using such physical analo- aimed at reducing risk will help to mitigate

gies as wheels of fortune and jars containing risk impacts.

colored balls. Care should be taken to

avoid encouraging thinking of independent * Risk reduction efforts requested by the

events as cyclic, with fixed return intervals, campaign should be equitable. All members of the community should be required

" Disagreements among experts should be to make sincere efforts to reduce the risk.

made explicit and not concealed. If possible, the range of opinions should have The specific strategies of the campaign

probability weights attached to the alterna- should rely, to the extent possible, on

tive possibilities, providing a feedback on risk reduction

efforts and providing economic and social

" The decision problem outcomes should be incentives for doing so.

framed in at least two ways, one stated as

losses from best case and one as gains from Design and Delivery

worst case. t- dditional guiding principles pertain to the

message design and delivery. These are:

"* Stress the analogy of the project to an

insurance policy against catastrophic loss * Messages should be vivid, that is, evoking

whenever this is appropriate. lifelike images within the akind.

• Messages should come from a credible

"• Provide information that allows the audi- source. Information from authoritative

ence to assess the risk (at least in terms of _ ______73
sources is more likely to be believed and,

therefore, acted upon.

" The message should be clear, specific,

concise, and concrete. Words used in a

message should immediately bring an

image to a person's mind. Specific but

concise messages are easier to read and

understand.

" The message should be clearly applicable to

the person receiving it. This requires that

information should be "personalized" or

"localized."

" The means for delivering the message

should make the maximum use of personto-person communication through local

media personalities, leaders, and citizen

advisory groups. Impersonal messages

should be avoided.

" Modeling of risk reduction behavior by

respected individuals in the community

should be sought as the most powerful

means of persuasion.

74.
Supplement of Examples to Chapter VI

This supplement presents additional examples part of actions contributing to flood protecthat illustrate some aspects of the basic tion. An illustration can be made from a

principles of risk communication discussed in study performed by Baumann et al. (1989)

Chapter VI. The main themes addressed in evaluating a public information campaign

Chapter VI are shown in Table S-1I encouraging floodplain residents in Illinois to

take protective measures against floods. This

These examples were extracted from case study showed that information can be an

studies and related materials that characterize effective component in the reduction of

potential flood damage, if the basic principles

Table S-1 of communication form are obeyed. Moreover, the authors show that for a program to

Communication Themes be effective, it need not be expensive nor

and Examples elaborate. It was shown that the leastintensive, least-costly program was as effective

Theme Example in bringing about change as the more intenEffectiveness of risk Example 1, 6, 7 sive and more costly programs. This is not to

communication conclude that any type of minimal informameasures tion prc-% r. '- will be effective in producing

Content of the Example 2 the desired changes in resident adoption of

message flood damage mitigation measures. The

authors attribute the source of the positive the notion results to successful risk-information conveyof probability ance (the design of the brochures). Thus,

World-view related Example 4citing the authors:

problems 1. The brochure was written to be underFeed-back from the Example 2, 5 stood by laymen; no professional or

audience technical jargon was used.

Corps missions and are intended to provide 2. The brochure was geographically personfurther insights for planners on how risk can alized through the use of a photograph of

be communicated at various stages in the a well-known landmark in the commuplanning process. nity on the cover of the brochure.

Example 1 3 ... a letter accompanied the brochure

signed by the mayor and by relevant

A Corps planner should seriously consider representatives of social, civic, and

public risk communication as an important business organizations ....

75
4. The brochure included information potential flood, should keep in mind that

concerning the economic costs and certain group behavioral patterns preventing

benefits of each flood damage mitigation flood or deficit-related damages may already be

measure ... existent among the local people. Risk recognition is not an alien factor which may be brought

Table S-2 "juxtaposes two figures-the total into the conscience of a social group by experts

cost of the information programs for each site only. On the contrary, it is often incorporated

and, again for each site, the per person into an algorithm of decision making which

average increase from pre- to post-program results as a form of adjustment of the group to

intervention in knowledge of flood mitigation certain conditions. Thus the planner should be

measures, positive attitude toward such prepared to address these issues in his message

measures, and actual practice of them." (whether positively or negatively).

TABLE S-2

Cost-Effectiveness of the Programs

Program Average per Person Pre- to Post-Program Increase In:

Cost ($) Knowledge Attitudes Behavior

Rockford 1,530 .612 1.851 .699

Wheaton 730 .610 1.724 .549

Oak Lawn 570 .618 1.763 .518

Libertyville 0 .491 1.622 .259

Source: Baumann et al. 1989

"A comparison of the estinated costs with the An example of such an adaptive pattern may be

per person net changes supports the conclu- found in the study of Moran (1979) who

sion that the program administered in Oak describes a decision tree that formalizes a

Lawn, the least-intensive program, is the most rancher's process of decision making under

cost-effective program. The total costs of the conditions of drought. The tree represents

Rockford program are nearly three-times relevant events and the expected consequences

greater than in Oak Lawn, yet there were no of each course of action (see Figure S- 1).

statistically significant differences in the net He concludes that "conditions such as extreme

changes per resident." cold, low biological productivity, and water

scarcity demand some form of adjustment by

E -xamp/e2 organisms occupying areas that are so constrained. In their process of adjustment,

A Corps planner, when preparing to convey populations must face the conflict arising from

76 risk information concerning water deficit or having to choose optimal solutions while
maintaining the flexibility necessary to cope formulated with care, for people tend to

with the future conditions" (p. 103). interpret that a flood "has to happen every

fifty years." Some may even conclude that a

ple -qxa 3 flood "will come next year, for it is already

forty-nine years since the last big flood!"

One of the problems a Corps planner may

encounter when implementing a risk This is an obvious misunderstanding of the

information campaign is a popular miscon- random character of weather and climate

ception concerning the meaning of the notion processes. The planner's responsibility is to

of probability, avoid such misunderstanding, either through

a careful wording ("once every fifty years"

It is tempting to put the message that "the would be, in the example above, a disastrous

yearly probability of flood in a certain region formulation) or by additional explication

is 1/50" into the form "floods happen here on revealing the metaphorical character of such

average once in fifty years." This should be formulations. It is better to express the

FIGURE S-1

CATTLE RANCHER DECISION TREE

St• Decision Tree Summarizing Options Open to a Cattle

Rancher during Drought In time A the situation is best

summarized as a 'dry spell.' If the rancher keeps his animals

and the spell continues, he will be unable to feed his livestock

from standing pastures. In time B, if he stays in the game, he

will have tofeed them from stored grain or hay. As drought

increases in seriousness, he will have to import grain, hay, and

water to keep his animals alive (time C) and will resort to

feeding them cacti, after burning off the spines, as a last resort

(time D). Usually ranchers get out of the game by selling all

or part of their herd before reaching points C or D. The

decisions made reflect perception of drought, frequency of

drought episodes in the habitat, and opportunity costs.

Source: Moran 1979, p. 100. 77
probability of such an occurrence by stating Interestingly, the degree of fatalistic (or

that the frequency of the event is most likely deterministic) attitude of a population may,

to occur once in fifty years, but it does not geographically, vary considerably. An

have to. account of the influence of the world-view on

human behavior in response to a hazard is

There is a natural human tendency to seek summarized by Sims (1989):

regularity in random or even chaotic patterns,

to impose order on the results of random "There is a puzzling hazard phenomenon of

processes. Feller (1968) offers one example long standing---the death rate from tornadoes

in risk monitoring: Londoners during the in the southern United States is significantly

Blitz devoted considerable effort to interpret- higher than in the Midwest. A number of

ing the pattern of German bombing, develop- investigations have attempted to account for

ing elaborate theories of where the German's this."

were aiming (and when to take cover).

However, a careful statistical analysis revealed "In this particular case, what was brought in

that the frequency of bomb-hits was ran- was a single psychological variable named

domly distributed. "internal-external locus of control." In

nonjargon terms, the issue is the extent to

Gilovich et al. (1985) found that basketball which one believes or does not believe that

players have no more shooting streaks than what one does largely determines what will

one might expect from a random process happen to one, that one's own actions, over

generated by their overall shooting percent- which one exercises control, determine the

age. This result runs strongly counter to the future. So-called internals see themselves as

conventional wisdom that players periodically relatively self-directed, whereas so-called

have a "hot hand," attributable to specific externals see themselves as moved by external

causes like a half-time talk or dedication to an forces such as fate, luck, or God."

injured teammate. One of the few basketball "Investigators found ... [that) the

experts to accept this result claimed that he midwestemers were more internal, placing

could not act on it anyway. Fans would not their faith in themselves and what they did

forgive him if, in the closing minutes of a notably to determine their lives (Baumann

game, he directed an inbound pass to a higher and Sims 1972) ... In contrast, southerners

percentage shooter, rather than to a player were more external, seeing themselves as

with an apparent "hot hand" (even knowing borne along the currents of destiny and

that opposing players would cluster on that fortune."

player, expecting the pass).

"... for midwesterners, a tornado warning

Exa le 4 mobilized them; they located other family

members, they battened down the hatches,

Another problem which a Corps planner may they sought shelter, they listened attentively to

encounter concerns a fatalistic world-view their radios or TVs for up-to-the-minute

("que sera, sera" - see Chapter VI for details information on sightings and direction.

on internal versus external locus of control'). Again, in contrast, southerners waited and 78
prayed. Theirs was a patient forbearance, a them. In such cases, lay perceptions of risk

fatalistic faith. If the tornado strikes, it strikes, should influence the experts' estimates."

there is nothing to be done to deflect its path,

and further, there is little to be done to Exa le 6

mitigate its effects."

An application of the theory of persuasive

Exa -ple 5 communication in designing maximally

effective messages for fostering water conserA danger to a successful risk communication vation behavior is described by Dziegielewski

campaign may result from a planner's falla- (1992). What is illustrated by this example is

cious assumption that risk communication that a media campaign based on principles of

has a uni-directional character: from experts successful risk communication may have a

to public. The public's intelligence should significant measurable impact on water

not be underestimated. conservation by a population facing a risk of

drought.

Planner must be sensitive to the response of

his audience, especially at the beginning of his Tables S-3 and S-4 illustrate principles of

campaign, not only in order to match the level persuasive communication as used in televiof risk recognition already existent in the sion commercials. Table S-5 summarizes the

conscience of the public, but even occasion- effects of the campaign. The tables and the

ally to learn some new elements of risk following excerpts come from Dziegielewski

situation. By ignoring feed-back from his (1992).

audience, the planner may make his message

highly unconvincing. There are examples of "In response to the recent drought affecting

situations in which information, well-known most of California, the Metropolitan Water

to the public, escapes the experts' attention. District (MWD) and some of its member

For instance Fischhoff (1989) recalls: agencies implemented a multimedia water

conservation campaign. The campaign was

"To take three examples: (1) the MacKenzie designed to inform the public about the

Valley (or Berger) inquiry discovered that drought and the potential water supply

natives of the far North knew things about the problems and to encourage specific water

risks created by ice-pack movement and conservation behavior. The media campaign,

sea-bed scouring that were unknown to the which included television, radio, print media,

pipeline's planners (Gamble 1979); (2) post- direct mail and bill inserts, was conducted

accident analyses often reveal that the opera- from the middle of June 1988 through

tors of machines were aware of problems that September 1988. The cost of MWD's paid

the designers of those machines had missed advertising was $1.3 million. The content of

(Sheridan 1980) and (3) scientists may shy the campaign messages was developed based

away from studying behavioral or psychologi- on the previously discussed results of research

cal effects (e.g., dizziness, tension) that are on socio-psychological aspects of human

hard to measure, and yet still are quite behavior and persuasive communication, and

apparent to the individuals who suffer from on prior experience in designing drought

79
Table S-3

Application of Principles of Persuasive Communication

Television Commercial A

Drought Campaign Messages Message Analysis: (Transcript)* Elements of Persuasive Communication

Announcer:

The drought is real.(a) Clear and unambiguous statement

intended to create the awareness of

drought.

Weathercaster:

And we need to save Information about what needs to be done.

all the water we can. Pronoun "we" used to secure a perception

of social support for the solution to the

problem.

If you've got an automatic This personalized message moves from an

washing machine it can use abstract problem to a concrete, everyday

50 gallons to wash just one situation. load.(b)

So before you run it The desirable behavior is suggested using

make sure it's full. very clear and direct information on what

to do.

The same goes for your The message is reinforced in a new

automatic dishwasher. context. The continued use of the

pronoun "you" directs the message

specifically to the viewer.

If everyone cuts back just Links the specific action to concrete

one load of clothes and dishes benefits of a concerted effort.

a week, we could save millions Reinforces social commitment and the

of gallons of water this summer. viewer's perception of efficacy.

Announcer:

LA's top TV weathercasters Emphasizes person-to-person

remind you.(c) communication and a credible source of

information.

The drought is real. The main theme (seriousness of drought)

And we need to save water. (a) is repeated. The desirable behavior is

reiterated.

Now. Simple and clear message to convey the

feeling of the urgency and immediacy of

the action.

Visual elements of persuasive communication:

(a) A still picture of a drying reservoir with parched sediment is shown.

(b) The announcer is demonstrating the recommended action (i.e., modeling the desired

behavior) while standing beside a washing machine.

(c) A live group shot of ten well-known weathercasters is shown.

*Transcribed here video tapes were provided by the Metropolitan Water District

Department of Public Affairs. 80
TABLE S-4

Application of Principles of Persuasive Communication

Television Commercial B

Drought Campaign Messages Message Analysis:

(Transcript) *Elements of Persuasive Communication

Screen:

How to save 11,743,410,000 A specific question that directs

gallons of water. attention to how to solve the problem.

A prior awareness of the drought is

assumed.

Announcer:

Your lawn can go an extra day A personalized message about an

without water. opportunity to conserve. Implies a

minimum cost (no sacrifice) involved.

To find out, ste on the grass. A clear, concise and simple instruction.

If it springs back up, it doesn't Supports the claim of "no sacrifice."

need water. (a) Encourages new behavior through

positive action while acknowledging values important to the viewer (e.g.,

proper lawn maintenance).

Think about it. The action's efficacy is explained. A

If every lawn in front of ever clear link is shown between one less

house in every town in all of lawn watering and the billion gallon

Southern California goes one extra savings. Pronoun "we" used to

day without water every week, we strengthen the social commitment.

would save billions of gallons

of water this summer.(b)

Easy. The simplicity of the statement

corresponds to the content of the

message (i.e., simplicity of the desirable

behavior modification).

And during the drought, that's Identifies the context (drought) for the

something the Metropolitan Water new desirable behavior and the

District wants everyone to know. credibility of the source.

Visual elements of persuasive communication:

(a) A homeowner (resident) models the behavior by stepping on the grass in his front

lawn while picking up the morning paper.

(b) An ascending aerial shot moving from the house's front yard to a street and finally to

the larger urban area accompanies the narrative. The camera stops at a receding water

line.

(c) The receding water line in a reservoir provides a depiction of drought. The logo of

MWD shown across the screen.

*Transcribed here video tapes with commercials were provided by the Metropolitan Water

District Department of Public Affairs.

I 81
Table S-5

Measurement of the Effects of the Drought

Percent of Responses

Self-Reported Behaviors and Attitudes Before After Change

A. Conservation Behaviors:

(1) Reported taking action to conserve water 65 72 +7

(2 )Watered lawn and shrubs less oftcn 25 30 +5

(3) Took shorter showers 15 19 +4

(4) Installed low-flow showerhead 14 20 +6

(5) Installed water savers in toilets 12 16 +4

(6) Used dishwasher (washing machine) less often 8 16 +8

(7) Repaired drips or leaks in faucets or toilets 8 11 +3

(8) Washed the car less often 6 10 +4

(9) Used broom rather than hose to clean driveway 5 9 +4

(10) Turned off water while brushing teeth or shaving 3 8 +5

(11) Watered lawn and shrubs at night 3 6 +3

(12) Reported number of conservation measures:b

None 38 26 -12

One measure 20 19 -1

Two measures 25 27 +2

Three or more measures 17 28 +11

B. Pro-Conservation Attitudes:

(1) Believed that there was a drought 50 58 +8

(2 )Believed there was a need to conserve 95 96 + 1*

(3) Believed in success of a concerted effort 59 60 + 1*

(4) Disagreed that farmers waste water 80 85 +5

(5) Agreed that they use more water than needed 30 21 -9

(6) Disagreed that agencies exaggerate the need 69 76 +7

(7) Disagreed that business and industry conserve 61 67 +6

C. Reported Efficacy of Conservation:

Perceived change in household's water use:c

So small you can't see it 26 20 -6

5 percent or less 13 14 +1

5 to 10 percent 24 25 +1

10 to 20 percent 19 20 +1

20 to 30 percent 10 12 +2

30 percent or more 8 9 +1

Source: Derived from Opitz and Dziegielewski (1989).

a. All changes are significant at the 0.05 probability level of the chi-square

statistic (except where indicated by the asterisk).

b. distribution of answers in the two samples is statistically different.

c. Distribution of answers in the two samples is not statistically different.

82
response programs. Tables S-3 and S-4 is demonstrated by statistically significant

provide two examples of the application of increases of 5 to 10 percent in pro-conservaprinciples of persuasive communication to the tion attitudes and conservation behaviors

content and form of campaign messages." before and after the campaign. Using an

econometric model of total water demand in

"Table S-5 compares the self-reported conser- Southern California, the actual water savings

vation behaviors, attitudes and perceptions of were estimated at 90,000 acre feet (111 hm3

)

survey respondents before and after the media [Chesnut and McSpadden, 19891. Assuming

campaign. The results indicate that the that all savings came from the residential

campaign messages had a significant impact sector, they represent a 4 percent reduction of

on the customers' water conservation behav- the expected residential water use in 1988."

ior. About 72 percent of respondents reported taking some action to conserve water. Ex"Ipe 7

This represented a 7 percent increase when

compared to the pre-campaign survey. The One observed phenomenon relevant to risk

frequency of reported conservation actions communication is the general tendency for

showed a significant increase for ten mea- people to ignore the risks of low probability,

sures, seven of which were recommended in and this attitude does not depend on a

campaign messages. Additionally, there was a particular type of hazard, be it flood,

significant increase in the total number of landslides, tornado, tsunami, volcano or

actions reported." earthquake.

"Most respondents believed in the efficacy of Some relevant conclusions were drawn on the

conservation in alleviating the effects of basis of results of an intensified risk commudrought. About 60 percent believed that they nication campaign that was undertaken in

saved 5 percent or more water as a result of conjunction with the Parkfield earthquake

their conservation efforts. However, both prediction as reviewed by Mileti et al. (1992).

surveys revealed the apparent lack of respon- Here are a few excerpts from this document

dent knowledge about the number of gallons which summarize the implications.

their household uses each day. About 21

percent were unable to risk a guess. Among "On November 16, 1984, two U.S. Geological

those who did only 9 percent were more or Survey (USGS) Scientists - William H. Bakun

less correct prior to the campaign and 13 and Allan G. Lindh - submitted to the

percent after the campaign. This slight National Earthquake Prediction Council data

increase was attributed to the information ... indicating that the chances of an earthquake

that was included in the campaign messages." were very high for the region around the tiny

town of Parkfield in central California....

"The overall conclusion of this survey research Within three months, both the national

is that the public information campaign had a council and the California Earthquake

significant impact on the residential water Prediction Evaluation Council had endorsed

users' knowledge, attitudes and behavior the scientists' prediction. Thus, the Parkfield

relevant to achieving water conservation. This Earthquake Prediction Experiment became

83
the first scientifically credible, long-term the print media for short-term risk warnings,

earthquake prediction approved by both the the responses to this survey showed that

National and California Earthquake Predic- printed matter delivered directly to homes is

tion Evaluation Councils. The Director of the most effective vehicle for informing

USGS issued a formal public forecast of the households about long-term risks.... Most of

quake in April 1985. The forecast stated that the people's preparations were the very things

there was a 90-percent probability of an that the brochure and other communications

earthquake with a Richter-scale magnitude of recommended. But people did not take these

5.5 to 6.0 occurring sometime between 1985 actions simply because they were publicly

and 1993 in the Parkfield area.... The release recommended. In fact, the survey showed

of this forecast became a national media that the prediction and subsequent informaevent, and residents of the area have received tion flow had no direct impact on the public's

streams of information about the prediction. behavior to get ready. Instead, what people

To date, however, no new or revised predic- did to mitigate and prepare for the quake was

tions have been issued for the next Parkfield the direct result of what people thought were

quake, nor has the earthquake occurred.... To their own ideas. In all three (surveyedl

determine if, how, and why the imperiled communities, personal ideas about what to do

population attempted to mitigate and prepare were formed while individuals interacted with

for the forecast earthquake, the authors of this other people, sought and discovered new

article selected three communities to study information about what to do on their own,

within the Parkfield area. Another goal was to and observed others' preparations.... The

advance the theory of risk communication by most o' vious lesson from this experience is

determining what would convince people to that one must disseminate a written brochure

take action." to the public. A written document gives

people something to refer to as they become

The findings of this research documented interested in the topic. If funds exist, mail the

again that "public belief in disaster risk brochure to people's homes.... The distriburequires a stream of comprehensive, repetitive tion of a brochure is not enough, however,

risk information from diverse sources," and and it must be supplemented.... People need

that, "the most believable sources are a mix of multiple information sources to reinforce

scientists and public officials." But more the risk information in the brochure.

specific conclusions were obtained: People seeing neighbors, friends, and

relatives preparing for the hazard is also

"Although previous research has indicated useful reinforcement."

that electronic media are more effective than

84
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ev.3. Oe1mm• PRZT~n O@iC&. 19M-3U0-7/9240

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Resources Planning - Part I, Underpinnings and Planning

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Part I, "Underpinnings and Planning Applications", provides observations

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