Reference Publications

*11104 104034

NBSIR 82-2485

Symbols for Industrial Safety

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Washington, DC 20234

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April 1982

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NBSIR 82-2485

SYMBOLS FOR INDUSTRIAL SAFETY

Belinda L. Collins

Neil D. Lerner

Brian C. Pierman

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Washington, DC 20234

April 1982

Sponsored by

National Institute of Occupational Safety and Health

U S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

ABSTRACT

Written signs are commonly used in industrial sites to provide hazard warnings

and safety information. The use of safety symbols may increase the effectiveness of safety communication, because such signs are language-free, and because

they can be recognized more rapidly and accurately than written text even

under some conditions of interference and distraction. The effectiveness of

safety symbols critically depends upon the selection of symbolic images which

are readily understandable to the intended audience. A four phase evaluation

of a set of selected industrial worksite symbols is described. The four phases

involved identification of 33 key safety messages, selection of candidate

symbols for each message, evaluation of the understandability of the candidate

symbols, and determination of the preference for the 87 candidate images, using

both industrial and nonindustrial (naive) personnel.

Symbol understandability, in terms of percentage of correct responses and

confusions, varied widely for the thirty-three referents. Despite standardized

use for a number of years, the radiation, biohazard, and laser symbols were frequently misidentif ied . Symbols for protective gear, first aid, and emergency equipment were generally correctly identified. The different images

selected for various hazards show the greatest range in understandability, with

the results for symbolic versions of entanglement, electricity, corrosion, and

overhead hazard being quite different. The preference data generally support

the understandability data, with the most correctly identified image usually

being the most preferred image. Participants also provided insightful comments

about the reasons for their choices, including ideas about the visibility,

representativeness, and effectiveness of the images proposed for each

referent

.

Key words: communication; hazard; pictogram; safety; signs; standards;

symbols; visual alerting; warnings

iii
ACKNOWLEDGMENT

While taking full responsibility for the contents of this report, the

authors wish to acknowledge the contributions of a number of people without

whose help this research project could not have been completed. In particular we wish to thank Jim Lark and Roger Jensen of NIOSH who gave essential,

valuable support throughout this project; Bob Andrews and Ralph Plummer who

provided immeasurable assistance both in locating industrial sites and in

testing their employees; the six companies who conducted extensive site

visits and reviewed their safety and signage programs with us; and finally,

those companies who provided both testing facilities and willing participants.

iv
EXECUTIVE SUMMARY

Written signs are commonly used in industrial sites to provide hazard warnings

and safety information. The use of safety symbols and pictorials may increase

the effectiveness of safety communication. Because such signs are languagefree, they can be recognized more rapidly and accurately than written signs, even under some conditions of interference and distraction. The effectiveness

of safety symbols critically depends upon the selection of symbolic images

which are readily understandable to the intended audience.

A four-phase evaluation of a set of selected workplace symbols is described

in the following pages. First, thirty-three messages (referents) important

to workplace safety were selected, based upon industrial site visits, sign catalogue review, and safety standard examination. These messages were divided into

five categories: hazards; protective gear; first aid and emergency equipment;

prohibited actions; and egress.

Secondly, two to 40 symbolic images were collected for each of the 33

referents. These images were rank-ordered according to their appropriateness

for a given referent by thirty participants drawn from the graphics and safety

communities. Three to five images for each referent (for a total of 87 images) were selected from the preference rankings for further experimentation, except

for five messages for which nationally standardized images already exist.

These include laser, biohazard, radiation, fire extinguisher, and standpipe.

The final set of images for each referent represented a range of abstraction,

complexity, activity, and use of the human figure. (The authors hypothesized

that less abstract figures engaging in activity might be better understood.)

The final two phases (conducted as a field study) consisted of both an understandability determination and a preference ranking. In the first phase,

222 employees from industrial plants in three disparate geographical locations

provided a short definition of the meaning of each image. The images were

shown one at a time in a random order. Subjects saw only one symbolic image

for each referent. In the second phase, all the images for each referent were

presented along with its intended meaning, and participants selected the image

that best conveyed the intended meaning to them, and indicated reasons for the

preference. Similar data were obtained from a pilot group of 78 participants

who were not familiar with workplace hazards, so that the effects of workplace

experience on symbol understandability could be examined.

Symbol understandability, in terras of percentage of correct responses and

confusions, varied widely for the thirty-three referents and for the images

tested for each referent. Despite standardized use for a number of years, the

radiation, biohazard, and laser symbols were frequently misidentif ied . Symbols

for protective gear, first aid and emergency equipment were generally correctly

identified. The different symbolic images selected for the various hazards

showed the greatest range in understandability, with versions for entanglement,

electricity, corrosion, and overhead hazard being quite different. Referent

messages for which all symbolic versions recieved less than 85 percent correct

responses included radiation, laser, biohazard, general warning, poison, com- bustible, eyewash, exit, no entrance and no exit. The first four referents did

v
particularly poorly for both informed and naive participants. The preference

data generally supported the understandability data, with the most correctly

identified image usually being the most preferred image. Participants also

provided insightful comments about the reasons for their choices, including

ideas about the visibility, pictorial nature, and effectiveness of the images

proposed for each referent.

The conclusions reached in this report are necessarily tentative, based upon

a small set of industrial employees. They do, however, provide some indication

of the image content which could communicate particular safety messages successfully. Further research into the effectiveness of workplace safety symbols and

hazard pictorials is now in progress.
TABLE OF CONTENTS

Page

ABSTRACT . iii

ACKNOWLEDGMENT iv

EXECUTIVE SUMMARY . v LIST OF FIGURES ix

LIST OF TABLES x SI CONVERSION xii

1. INTRODUCTION 1

1.1 Need for Symbol Use 1 1.2 Requirements for Research on Workplace Safety Symbols 2

2 . OVERVIEW OF SYMBOL RESEARCH LITERATURE 4

2 . 1 Background 4

2.2 Highway Symbol Research 4

2.2.1 Direct Comparison of Word and Symbol Signs 4

2.2.2 Assessment of Meaningfulness 7 2.2.3 Behavioral Observations of Symbol Effectiveness 8

2.2.4 Visibility of Highway Symbols 8

2.3 Automotive and Machinery Symbols 9

2.4 Public Information Symbols 12

2.5 Product Labeling Symbols 14

2.6 Safety Symbols . 15

3. DEVELOPMENT OF WORKPLACE SAFETY SYMBOLS REFERENTS 17

3.1 Overall Procedures 17

3.2 Site Visits 17

3.3 Sign Catalogues, Publications and Manufacturers 20

3.4 Review of Symbol Standards 22

3.5 Symbol Referents Recommended for Study 22

4. RESEARCH ON WORKPLACE SYMBOLS 26

4.1 Effective Symbols: Research Focus 26

4.1.1 Background 26

4.1.2 Symbol Selection Procedure 26

4.2 Specific Image Selection 27

vii
TABLE OF CONTENTS (continued)

Page

4.3

Method 33

4.3.1 Experimental Procedure 33

4.3.2 Pilot Experiment 33

4.3.3 Industrial Site Participants 34

4.3.4 Symbols Tested 34

4.3.5 Stimulus Material 35

4.3.6 Procedure 35

4.3.7 Scoring of Response Protocols 36

5. RESULTS AND DISCUSSION 37

5.1 General Results 37

5.2 Discussion of Specific Findings 38

5.2.1 Overview 38

5.2.2 Hazard Warning Messages 39

5.2.3 Prohibited Action Messages 59

5.2.4 Safety and Fire Emergency Messages 59

5.2.5 Personal Protective Gear 67

5.2.6 Egress - Related Referents 75

6. CONCLUSIONS 85

6.1 Preliminary Selection of Image Content 85

6.2 General Conclusions 86

REFERENCES 98

APPENDIX A 103

APPENDIX B 109

APPENDIX C 131

viii
LIST OF TABLES

Page

Table 1. Common Generic Messages from Site Visits 19

Table 2. Symbols Typically Available from Sign Catalogues 21

Table 3. Symbol Referents Standardized by ISO and the EEC for

European Use 23

Table 4. Selected List of Symbol Referents for Experimental Study 25

Table 5. Concepts and Images Selected for Experimental Research 28

Table 6. Selection Basis for Symbols Which Represent Particular

Referents 87

ix
LIST OF FIGURES

Page

Figure 1. Danger, electrical hazard AO

Figure 2. Danger, explosive hazard 41

Figure 3. Danger, flammable hazard 43

Figure 4. Danger, corrosion hazard 44

Figure 5. Danger, poison hazard 46

Figure 6. Danger, entanglement hazard 47

Figure 7 . Danger of slipping 48

Figure 8. Danger of tripping or falling 50

Figure 9. Danger, fork lift operating in area 51

Figure 10. Danger, overhead hazard 53

Figure 11. General warning 54

Figure 12 . Three specialized hazards 56

Figure 13. No open flame 58

Figure 14 . No smoking 60

Figure 15. First aid 61

Figure 16. Safety shower location 62

Figure 17 . Eyewash location 64

Figure 18. Fire safety equipment 65

Figure 19. Fire alarm call point 66

Figure 20. Head protection required 68

Figure 21. Ear protection required 69

Figure 22. Eye protection required 70

Figure 23. Hand protection required 72

Figure 24. Foot protection required 73

x
LIST OF FIGURES

Page

Figure 25. Respiratory protection required 74

Figure 26. Emergency exit 76

Figure 27. Exit 78

Figure 28. No exit 79

Figure 29. No entry 81

Figure 30. Use stairs in case of fire, not elevator 82

Figure 31. Three additional symbols 83

Figure 32. Symbols selected to represent each referent 90
SI CONVERSION

The units and conversion factors given in this table are in agreement with the

International System of Units or SI system (Systeme International d’Unites).

Because the United States is a signatory to the 11th General Conference on Weights and Measures which defined and gave official status to the SI system,

the following conversion factors are given.

Length

1 inch = 0.0254* meter

1 foot = 0.3048* meter

Area

1 square inch = 6.4516* x 10~^ raeter^

1 square foot = 0.0929 meter2

Volume

1 cubic foot (ft3) = 0.0283 raeter^

* Exactly
1 . INTRODUCTION

1.1 NEED FOR SYMBOL USE

Written signs have traditionally provided information to guide, protect, and

inform people in buildings in the United States. Written signs are commonly

used in industrial settings, where they play an important role in worker safety.

The importance of worker safety is underscored by the statistics that more than

5.6 million people were injured, and at least 4500 were killed, in workplace

accidents in the United States in 1978 (Bureau of Labor Statistics, 1979).

Injury is most likely during the first month on the job, and the "incidence of

injury or illness decreases with length of service in all age groups" (National

Safety Council, 1979, p. 26). Consequently, signs may be particularly important in alerting the new worker who is less familiar with existing hazards and

precautions. Despite the prevalence of written signs, however, these may not

be the best way of conveying necessary information. As a result, there has

been a tremendous growth in the use of pictograms or symbols. With these, the

information is conveyed pictorially, often without word labels.

The modern use of pictograms began with the development of standardized traffic

symbols in Europe in the early part of this century. Currently, there is

increasing use of symbols within the United States for transportation systems,

hazard warnings, fire safety, and public information. For example, the

Department of Transportation (DoT) successfully sponsored the implementation of

standard symbols for motorists, and has proposed other symbols for public information in transportation facilities. Increased concern for worker safety and

consumer protection has sparked interest in the United States in the use of

symbols as a viable means of communicating safety information.

Pictorial signs or symbols, when chosen appropriately, have been demonstrated to

be more effective than words. Thus, symbols can be recognized more rapidly

(Janda & Volk, 1934) and more accurately (Walker, Nicolay & Stearns, 1965) even

under conditions of interference or distraction (King, 1975; Ells & Dewar,

1979). Furthermore, they often occupy less space (Forbes, Gervais & Allen,

1963) and may be more effective in altering behavior (Forbes et al., 1963). In

addition, they provide information without the use of a specific written

language

.

The reasons for developing symbols for use in industrial settings lie in the numerous advantages of symbols. The primary advantage is that pictures communicate information without the use of written language (Mead & Modley, 1968;

Modley 1966). Symbols have been used in Europe because the prevalence of international travel and trade created the need to overcome language barriers

(Kolers, 1969). Even within the U.S., there are large numbers of people who do

not read or speak English well. Because there are no established criteria for

functional literacy, estimates of illiteracy vary widely from about two million

to about 64 million adult Americans (Kirsch & Guthrie, 1977-1978; Washington

Post, 1979). Furthermore , Bureau of the Census data, collected in 1976, indicated that English was not the native language for about eight million people

the 1J.S. Of these, about five million reported difficulty in speaking or understanding English. (There were no reported data on reading skills). For

1
those whose native language is not English or who are functionally illiterate,

symbols could be the only visual warnings for preventing accidents and

providing protection.

1 .2 REQUIREMENTS FOR RESEARCH ON WORKPLACE SAFETY SYMBOLS

An overview of the research literature on symbols (presented in more detail in

section 2.0), underlines some additional advantages of symbols. Among the

major advantages are that pictograms can, in some cases, be perceived more rapidly (Janda & Volk, 1934), more accurately (Walker, Nicolay & Stearns, 1965),

and at a greater distance (Smith & Weir, 1978) than words. Reaction time may

be shorter to symbols (Smith & Weir, 1978), even under conditions of stress

(Smillie, 1978). Symbol meanings can often be rapidly learned and accurately

remembered (Walker, et al., 1965), with minimal confusion among alternatives

(Green & Pew, 1978). Symbols may also be superior to words under conditions of

interference either by distraction from another task (King & Tierney, 1970) or

by visual interference or degradation (Ells & Dewar, 1979). These advantages

of symbols over words may not be true under all conditions, however.

Most of this research has focused on highway signs, with some attention to

applications such as automotive machinery and product labeling. Yet these

experiments have, for the most part, ignored the use of symbols to convey

safety messages within buildings. As a result, their effectiveness for this

purpose has rarely been evaluated.

Although symbols can be more effective than written signs, their effectiveness

depends heavily upon selecting symbols which are readily understandable. Simply drawing a picture is not sufficient. The picture must be evaluated in a systematic research program. Yet, this evaluative stage is rarely done,

because symbols are typically developed and implemented in response to an individual, specific need. Although the creator of a symbol may understand its

meaning perfectly, this message may not be communicated to anyone else. Collins

and Pieman ( 1979) and Lerner and Collins (1980) noted that several fire-safety

symbols developed by ISO TC 21 communicated a meaning which was the opposite

of the intended message. A situation in which a symbol communicates an opposite meaning illustrates the most serious problem with the use of symbols. As

a result, before symbols are standardized, particularly for safety situations,

their effectiveness in communicating the appropriate message must be evaluated.

Once a symbol has been developed to fill a specific set of needs and researched

to determine its effectiveness, it should be standardized for a given application. A major problem currently is that anyone who feels the need for a symbol

develops one, often without reference to existing symbol sets. Figure 2 shows

an example of eight different conceptualizations for symbolizing hearing protection. Each of these basic forms may have several graphically distinct ren- ditions in use. This illustrates how the same message may have several different graphic images. If the representation of each of these symbols is very

different, the potential for serious confusion is great. Therefore, there is

a need to develop consistent and ultimately standard sets of safety symbols for use iu workplaces. Because the signs currently used in workplaces provide

critical information for preventing accidents and for providing personal

2
protection, failure to develop and implement consistent, well recognized

symbols is potentially dangerous.

The task of developing effective workplace symbols is threefold. First, a determination must be made of the kinds of situations which require symbols.

Exactly what messages, or referents, need to be conveyed and for which hazards?

Secondly, a set of candidate symbols must be selected for each referent, particularly where there have been numerous attempts to symbolize a given referent.

Thirdly, the various proposed symbols must be evaluated to determine if they,

in fact, communicate the desired meaning to the target audience. In this process, it is important to realize that because some situations are more difficult than others to symbolize, the process of developing effective symbols must

be an evolutionary one.

In the following pages we will review the research literature; describe site

visits and conclusions from visits to factories; review catalogues and correspondence with numerous sign manufacturers; develop a list of symbol referents

for further investigation; review national and international standards for symbol use; present an experimental evaluation of symbolic images for 33 different

safety messages; and discuss recommendations for the use of safety symbols in

industrial settings.

3
2. OVERVIEW OF SYMBOL RESEARCH LITERATURE

2 . 1 BACKGROUND

Before symbols are implemented as part of a communication system, their

effectiveness in conveying information and producing the desired behavior must

be evaluated. For a symbol to elicit a behavioral response, a series of psycho

logical processes must be completed. These include detection, discrimination,

recognition, and understanding (or identification). (For a further discussion

of perceptual information processing, see Schiff, 1980.) A symbol must be

effective at each stage of this process if it is to be a reliable means of

communication. Research on symbols has focused on various stages, asking such

questions as: How detectable is the symbol? How discriminable is it from all

other symbols? How recognizable is it when seen in a different context? How

well does it communicate the desired meaning? How effectively does it alter

behavior? In addition, some experimenters have assessed people’s attitudes

toward, and preferences for, specific symbols.

In the literature review that follows, it will become apparent that some stages

of the communication process have received relatively little research attention

Furthermore, most symbol systems have not been studied systematically. For the

most part, researchers have concentrated on detectability and understandability

as the major research areas for symbols. Although the bulk of the research has

concentrated upon highway symbols, this review will discuss the application of

symbols in four areas: road and highway symbols; vehicle and machine symbols;

public information and directional symbols; and product hazard symbols. Work"

place safety symbols have received little research attention, although some relevant experimental results will be discussed at the end of this review.

2.2 HIGHWAY SYMBOL RESEARCH

The bulk of the highway symbol research has centered upon a comparison of the

effectiveness of word and symbol signs, typically for response accuracy or reaction time. In several other instances, a set of symbols has been directly

evaluated for its understandability. Finally, several investigators have

assessed the effectiveness of highway symbols in terms of perceived meaningfulness, discriminability , or alteration of behavior.

2.2.1 Direct Comparison of Word and Symbol Signs

One of the first highway symbol experiments was conducted by Janda and Volk

(1934) who assessed the speed of reaction to 20 signs and symbols. They also

assessed the correctness of response by having subjects push a lever in the

direction indicated by the various symbols and signs. Reaction time was shortest for the symbols and greatest for the words alone with a total difference of

200 msec. In addition, speed of response increased with repeated trials. The

authors claimed consequently that word signs are a relatively poor way of

conveying information to people.

In a later comparison of word and symbol signs, Walker, Nicolay, and Stearns

(1965) compared both the accuracy of understanding and the ease of learning for

4
international highway symbols and U.S. highway (word) signs. The aut ors presented seven black and white signs and symbols for .06 sec tachistoscopically

after five minutes of familiarization.

Subjects identified the nature of the sign or symbol in writing, after it was presented briefly. This procedure was repeated using colored stimuli for a new

set of subjects. Finally, subjects defined the meaning of the symbols in a subsequent test of retention. In all cases, the authors found that the international symbols were identified significantly more accurately than the word

signs regardless of color and delay before re-testing. They attributed the

better performance of symbols to their perceptual simplicity and visual

integration.

A number of researchers have used a measure termed "glance legibility" to assess the effectiveness of word and symbol signs. As defined by King (1971,

1975), glance legibility is the percentage of correct matches between a symbol

(or word) stimulus and an answer chosen from an array of symbols or words. The

tachistoscopic presentation of the test stimulus is limited to brief exposures.

Both the time to make the match and the accuraccy of the match are recorded.

Glance legibility essentially measures the recognizability of a symbol.

King (1971) used the glance legibility procedure to compare the meaningfulness

of two series of 10 symbols each with one series of 10 road signs for 208

subjects. First, King had subjects give a definition for each symbol. Then,

King presented each symbol briefly (.05 sec and .3 sec) so that subjects could

match it against an answer array of nine symbols. King found that there were significant differences in the accuracy of response for the two series of

symbols; the series which contained prohibitory symbols proved to be especially

difficult to define. When glance legibility was assessed, the percentage of

correct matches decreased for word signs as presentation time decreased, but

not for symbol signs. There were no differences in correct response between

the two series of symbols, however. Finally, 65 percent of King's subjects

claimed that the symbol signs were easier to match than the word signs. Thus,

although the word signs may have been initially more meaningful, under short

presentation times, symbols were more recognizable and more accurately matched.

In a subsequent experiment, King (1975) used the glance legibility approach to

study the effects of delayed response with and without interference during the

delay, upon the accuracy of symbol recognition. Under actual driving conditions, there is typically a time interval between observing a highway sign and

acting upon it. In addition, the driver usually performs some other drivingrelated task during this time interval. Consequently, King (1975) repeated

his earlier experimental procedure but delayed the subject's response for

intervals of 5 and 10 seconds and added an interference task during another 10

second interval. The symbols, signs, and presentation durations used in King

(1971) were repeated. For the short (.05 sec) viewing conditions, the percentage of errors increased for both the 10 sec delay and interference conditions.

In addition, even more errors occurred for the word signs under interference

conditions. King suggested that his results indicate that symbols retain their

superiority under difficult viewing conditions.

5
Plummer, Minarch, and King (1974) also used the glance legibility task to

compare reaction time and response accuracy for 10 highway word and symbol

signs. They presented a single word or symbol for 200 msec. Subjects selected

an answer from an array containing either three words or three symbols which was presented for 6 sec. Each comparison was repeated 3 times for a total of 60

observations for each subject. In addition 10 subjects received special training

on highway signs. The authors found that the reaction time, or time to select

an answer from the answer array and depress the correct button, was slower for

symbol signs than for word signs. The response to symbols was significantly

more accurate, however. Prior training decreased reaction time but did not

affect accuracy. Finally, individual symbols varied both in response time and

recognition accuracy.

Dewar (1976) used the glance legibility procedure to determine the effects of a prohibitory slash upon symbol recognition. Fifteen symbols were studied under

four different ways of symbolizing prohibition: slash superimposed on the

symbol, symbol superimposed on the slash, partial slash, and circular red

surround. Both normal and degraded viewing conditions were studied. In each,

legibility was greatest for symbols with a red surround and least for symbols

with the symbol superimposed upon the prohibitory slash. Nevertheless, because

the use of a red circle to indicate prohibition would not be effective for most

color defective people, Dewar recommended the use of a partial slash.

It is important to remember that Dewar's (1976) experiment was a recognition

experiment in which he did not assess the meaningfulness of the various prohibitory conditions or compare different permissive and prohibitory versions of

the same symbols. Nevertheless, his results do indicate that the slash can

impair the detectability of the symbol underneath. As a result, it is particularly important to ensure that the underlying symbol is not overly complex.

Resolving the issue of complexity is, in itself, a difficult question which

deserves further research.

In a later experiment Dewar and Ells (1977) compared accuracy scores from a glance legibility experiment with the meaningfulness of the same symbols using

the semantic differential. The semantic differential measures the raeaningful- ness of a word or idea by having subjects rate the sign on a set of scales made

up of bipolar adjective pairs. In a test of 20 traffic symbols, Dewar and Ells

found that meaningfulness as defined by the semantic differential was highly

correlated with the accuracy of a subject's definition of a symbol. In a second experiment, Dewar and Ells were able to correlate glance legibility with

semantic meaningfulness only for word signs, not for symbol signs. The authors

did not explain this lack of correlation but suggested that both semantic differential and glance legibility measures are needed to provide a complete picture of a symbol's raeaningfulness and recognizability

.

In a reaction time experiment which did not use the glance legibility procedure,

Dewar, Ells and Mundy (1976) compared the effectiveness of word and symbol signs

for three tasks of increasing complexity. In the first task, subjects were shown slides of 26 signs (half verbal and half symbolic) and asked to classify

20 of these as either regulatory or warning. Reaction time was measured from

the onset of the slide to the onset of the verbal (classification) response.

6
In this study, the experimenter first read a traffic sign message aloud. T'e

subject then viewed a slide of a traffic sign and responded "yes" or "no" if the

visual sign and the verbal message were the same. The time to initiate the verbal response was measured. Stimuli were viewed under both normal and degraded

conditions. In this experiment, reaction time was always shortest for symbolic

messages. In addition, response time increased more for verbal signs than for

symbolic signs under degraded viewing conditions. Thus, the change in response

method from the Dewar and EUS (1977) procedure) enabled the more rapid detectability of symbolic messages to be measured under all viewing conditions.

These experiments indicate clearly that symbolic signs can be more effective

than verbal signs, if the response measures and viewing conditions are chosen

appropriately. Because the use of a strictly verbal labeling response would

appear to bias the reaction time data toward word signs, Ells and Dewar's (1979)

experiment offers an interesting experimental approach alternative. Nevertheless, the use of reaction time as a measure provides an index of some of the

demands of actual driving, where the speed of responding to a sign's message

can be critical.

2.2.2 Assessment of Meaningfulness

In a different experimental approach, highway symbols have also been directly

evaluated in terras of their understandability . Meaningfulness has typically

been assessed to determine if a set of symbols is accurately understood. Speed

of response has not been a critical variable in these experiments.

In one of the first assessments of highwway symbol meaningfulness, Brainard,

Campbell, and Elkin (1961) evaluated the effectiveness of 30 European symbol

signs. Meaning was assessed first by having subjects either give a definition

for each symbol or select the correct answer from an array. Following this,

subjects received a brief training period after which they again provided

definitions for each of the symbols. Next subjects sketched their idea of an appropriate symbol for each of 16 definitions. Finally, a new set of subjects

gave definitions for each of the new symbol signs.

Brianard et al. found a high correlation between the answers for both the

definition and selection answers, although there were fewer correct answers for

the definitions (54 percent rather than 74 percent). Training improved the

percentage of correct answers to nearly 100 percent for both response modes.

The analysis of the drawings revealed common stereotypes for at least nine of

the 16 definitions and common elements for the majority of the symbols. Testing of symbols based upon these stereotypes revealed that the percentage of

initially correct answers to them was greater than for the European symbol signs

in all instances. The signs with the lowest scores tended to be more abstract

or to use a prohibitory slash. Brainard et al. found that the meaning of prohibitory signs was frequently reversed, although brief training on all symbols

improved accuracy to near 100 percent. It should be remembered that this

experiment was published in 1961, before the current extensive use of prohibitory circle-slash signs by the Department of Transportation, so that more

recent studies might have not unearthed a similar problem.

7
Griffith and Actkinson (1977, 1978) also evaluated the understandability of

highway symbols. They determined the effectiveness of 128 road symbols used in

Germany. Using U.S. Army personnel, they found that at least 10 of the 128

signs were misunderstood by more than 50 percent of the subjects, and that the

overall percentage of errors upon first exposure was quite high. In addtion,

they also found that memory cues and verbal elaboration were not significantly

effective as training procedures, although each reduced errors somewhat. As a result, these authors questioned the ready interpretability of many highway

symbols and claimed that their subjects had trouble with more abstract and

less directly representational symbols.

Although Griffith and Actkinson did not comment upon it, the very large number

of symbols studied (128) may have caused problems—particularly since some contradict U.S. practice. In some instances, for example, a red circle alone

was used to indicate prohibition, with the slash used to lift the restriction,

so that the meaning became in essence a double negative. By contrast in the

U.S., a red circle is used with the slash to indicate prohibition. As a result,

it is not surprising that Griffith and Actkinson' s subjects had problems with

these symbols.

2.2.3 Behavioral Observations of Symbol Effectiveness

The meaningfulness of symbols has also been assessed directly by determining

their effectiveness in altering behavior. Forbes, Gervais , and Allen (1963),

for example, developed a lane-control symbol in a set of laboratory experiments,

and then tested its effectiveness on the highway. In the initial tests, the

authors determined that a red "X" appeared to be most effective in controlling

traffic lane use. This symbol was then tested under actual highway conditions,

in which a lane was closed off by a lightweight barrier. Presence of the barrier was indicated by the red "X" . Thus, Forbes et al. found a symbol which

tested well under both laboratory and actual highway conditions.

In a similar experiment, Dewar and Swanson (1972) evaluated a set of symbols in

a laboratory setting and then tested some of these symbols under actual driving

conditions. Initially, they compared twenty-three word and symbol signs by

having subjects define each one when presented under short viewing conditions

(.04 sec). The signs were presented first by themselves, and then in a picture

of a road intersection. For the most part, the symbols were recognized more

accurately than the words , although some combinations of symbols and words

reduced understandability compared with either alone. In a subsequent highway

experiment, the relative effectiveness of positive (prescriptive) and negative

(proscriptive) symbols for "no left turn" was determined by counting the number

of cars making illegal left turns at an intersection. The positive symbol

appeared to be more effective in altering behavior in the desired direction

than the prohibition symbol.

2.2.4 Visibility of Highway Symbols

In the final experiment to be reported on highway symbols, the discriminability

of a symbol was determined for different visibilities. Smith and Weir (1978)

evaluated the effectiveness of eight different directional symbols under

8
conditions of blur and low contrast. "Blur" simulated the effects of different

visual acuities upon visibility, particularly for nighttime conditions, while

"contrast" simulated the effects of glare, as from bright sunshine. Eight

levels of both blur and contrast were studied. In both experiments, subjects

judged the direction in which the symbols pointed. Smith and Weir also determined subjective assessments of each of the 8 directional symbols. In this

phase, subjects arranged photographs of the 8 symbols according to their suitability as a directional indicator. Smith and Weir found that although two

symbols tested particularly well in terms of visibility criteria, one of these

symbols was ranked as the least acceptable symbol. As a result, they suggested

that criteria for symbol effectiveness must consider not only detectability and

discrirainability but also subjective response. The most effective symbol should

perform well under all criteria.

2.3 AUTOMOTIVE AND MACHINERY SYMBOLS

Pictograms and symbols are also used to mark controls and to provide operating

information in cars, trucks, and machinery. The impetus for this application

derives from the international sale of machinery and equipment and the consequent need to convey equipment operating information accurately without the use of written language. Because symbols can be smaller than a comparable

word phrase, they are preferred to lengthy written instructions for providing

operating information.

Unlike highway symbol research, research into automotive-machinery symbols has

focused on evaluating the effectiveness of one or more sets of symbols for a particular referent. Rarely have researchers compared symbols with words or evaluated reaction time. Rather, the focus has been upon determining the

meaningfulness of a set of symbols for a particular audience.

Cahill (1975, 1976) evaluated the interpretability of some of the symbols

proposed by Dreyfuss (1966) for use on farm vehicles and industrial machinery.

She studied the effects of both context and previous experience upon the understandability of ten selected symbols for 30 male subjects. Context was provided by using a drawing of the interior of a cab for a piece of heavy equipment so that subjects could locate the appropriate place for each symbol, and

perhaps derive some meaning from this "context". Half the subjects received

context; half did not. All subjects viewed slides of the symbols and provided

definitions for each. Subjects were considered "experienced" if they had

operated, designed, or serviced heavy industrial or farm equipment.

Analysis of the results indicated that context and previous experience

facilitated accurate recognition of the symbols, although there was wide variability in the understandability of individual symbols. Furthermore, although

context improved performance, it did not alter the relative ranking of the

understandable symbols. Cahill (1976) noted that the understandability of the

symbols appeared to be influenced by the kind of graphic representation used.

For example, symbols such as "fuel," "horn," and "turn signal" were understood

by most subjects. Cahill commented that these symbols are fairly direct

pictorial representations of commonly encountered objects. Other symbols such

as "engage" and "choke” were understood by very few subjects; neither received

9
a correct response from the "no context" group. Cahill (1976) claimed that,

because these symbols are conceptual rather than pictographic representations,

they are not all familiar even to technologically sophisticated users. In

these instances, although experience and context can provide useful cues, symbol

design is critical in determining the understandability of a particular symbol.

In a study of automotive control symbols, symbol design was also found to be a critical variable. Wiegand and Glumm (1979) evaluated the effectiveness of a single set of symbols proposed by ISO by having 125 U.S. subjects match pictures

of 25 symbols to a list of 35 definitions. The percentage of correct identification was above 80 percent for 20 of the 25 symbols. Yet, two of the symbols,

"choke" and "master lighting switch" performed poorly enough to warrant redesign

Wiegand and Glumm suggested that knowledge of the understandability of a set of

symbols can be used to indicate where additional design or education is needed.

One of the best ways of selecting a set of symbols for standardization is to

test several different graphic representations for each idea (referent). Thus,

Heard (1974) evaluated the effectiveness of three different symbols for each of

24 referents for a very large number (2593) of licensed drivers in four countries. She studied three age groups as well: 16-25, 26-55, and over 55.

A total of 54 symbols were studied—three variations of each of 15 ISO symbols

and one variation of 9 other symbols. These symbols were tested in the appropriate location in an actual automobile or an automotive mock-up. As subjects

were read a driving scenario which involved each of 24 symbols, they touched

each control at the appropriate place, using the symbol for identification.

The time to find and touch the correct symbol was measured to the nearest

0.5 sec. Accuracy of response was also recorded.

Heard was able to select one symbol for each of twelve referents based upon

significant experimental differences between the symbols in the three proposed

sets. For recommendation, a symbol had to be understood correctly by more than

75 percent of the subjects and to be confused with other symbols no more than 5

percent of the time. Based upon these criteria. Heard (1974) recommended a set

of symbols which performed significantly better than all other symbols in an actual vehicle under simulated driving situations.

Green and Pew (1978) also examined the effectiveness of 19 pictographic symbols

used in automotive displays. They employed fifty subjects in a series of five

tasks. First, they determined the subjects' familiarity with the symbol, by

having them circle those that they were "reasonably sure" that they had seen

before. Secondly, in a determination of "association norm" for each symbol,

subjects were read driving scenarios similar to those used by Heard (1974) and

asked to indicate which of several symbols was appropriate for each scenario.

In the third task, subjects made estimations of the magnitude of the "communicativeness" of each symbol, (or how well it conveyed the desired meaning). In

the fourth task, subjects were given training until they could associate each

label correctly with the appropriate symbol. Finally, reaction time was assessed by recording the amount of time until the subject could respond "same”

or "different" to a picture of the symbol and a label read by the experimenter.

10
Green and Pew found that education (technical vs. non-technical) , road

experience, and specific vehicle experience all affected a subject’s symbol

knowledge. In addition, analysis of task 1, familiarity, indicated that most

symbols were unfamiliar; the mean number of familiar symbols was 2.6 out of a possible 19. The second task indicated that only 6 out of 19 symbols tested

met Heard's acceptance criteria of minimum 75 percent recognition and maximum

5 percent confusion. In fact, many of the symbols which were confused with

each other were also rated as being very poor for communication. Nevertheless,

subjects were able to learn the symbol label pairs of the fourth task relatively

rapidly (usually in 3 trials). Results for the fifth task, reaction time, indicated both a pronounced learning effect and variation in a subject's ability to

do the task rapidly.

When Green and Pew examined correlations between tasks, they found that neither

familiarity nor associative strength was strongly correlated with reaction time

measures. Rated communicativeness, however, was highly correlated with associative strength and reaction time. Hence, this measure could conceivably be

used as an effective measure of the utility of a symbol. The authors also

noted that although sex and technical ability affected the initial recognition

of a symbol, these did not appear to affect performance on the other tasks.

Furthermore, although reaction time decrease with learning, it was affected by

the discriminability of an individual symbol. Finally, the authors concluded

that it is important to interview subjects to understand why specific symbols

are mistaken and confused. The numerous confusions and mistakes reported by

Green and Pew underline the need to research the understandability of specific

symbols

.

Because previous research had shown variability in the understandability of

symbols, Green (1979) explored the development of better symbols for automotive

controls and displays. First, Green had subjects draw symbols for each of seven referents. Then another group rated the meaningfulness of the six or seven most frequently drawn symbols for each referent.

In the first phase, 43 subjects drew pictures of seven referents—heater, air

conditioner, fresh air vent, radio volume, radio tuning, tire pressure, and

lamp failure. Three judges then scored these ratings by giving them labels

such as "fire" or snowflake" or some similar term. The drawings were then

grouped by label and the most frequently suggested drawings were used a stimuli

for the second phase. In the second phase, 62 subjects gave estimates of the

informativeness of the newly drawn symbols. Subjects were given sheets upon

which the referent (label) appeared in the center surrounded by four to ten

candidate symbols. Subjects made magnitude estimations of the informativeness

of each suggested symbol for the various referents. Analysis of the data

indicated that subjects were able to agree upon at least one symbol for each

referent. These symbols did not always agree with those in common use, however.

Green (1979) concluded that having people draw symbols for proposed referents

(the "production method") should be the first step in data collection for symbol

research. Magnitude estimation should then be used to select the "best" of

these symbols for a given referent for further study.

11
In a study of symbol discriminability , Green and Davis (1976) explored the

effects of variation in the orientation of automotive symbol controls. Previous research, such as Heard (1974), evaluated the recognizability of automotive symbols placed in an upright position only. Yet symbols placed upon

controls are often rotated away from upright, and consequently may not be

rapidly or accurately identified.

Green and Davis presented ten subjects with three different symbols which

varied in orientation. Subjects were given a page with numerous pairs of

symbols, one of which varied in orientation. Half of the varied symbols were

also reversed (mirror image). Subjects judged whether the symbol pairs were

the same (S) or different (D) (mirror image reversed). Analysis of the results

indicated that increasing the rotation of the symbol away from upright significantly affected response time for deciding if both members of the pair were the same. Green and Davis commented that this delayed reaction could be hazardous

in an actual driving situation. As a result, because a driver could have

difficulty in responding appropriately in an emergency, control symbols should

always be mounted in an upright position. The problem of rotated symbols is

greatest for controls which themselves can be moved away from a "normal" position.

2.4 PUBLIC INFORMATION SYMBOLS

The third application of symbols to be discussed is that of public information

symbols. These are symbols which provide primarily directional information to

the general public. Intended to be understood by a wide variety of people who

do not speak a common language, they are frequently used in transportation

facilities

.

Research in this area has typically focused upon the meaningfulness, or understandability , of a set of symbols. For example, Easterby and Zwaga (1976)

assessed the meaningfulness of various symbols for six informational referents

under the sponsorship of the ISO. In a three stage experiment, they determined

the "best" symbol for the following referents: drinking water, information,

stairs, taxi, toilets, and waiting room. First a small sample of subjects from

the U.K. and the Netherlands ranked a large number of symbols in terras of their

"appropriateness" for a given referent. Three symbols were chosen from these

rankings for each referent for further research. In the second phase, subjects

from six countries gave meanings for each of the three symbols sets.

Easterby and Zwaga found that subjects were able to provide a more-or-less

accurate definition for some symbols. Other symbols, however, received few

correct definitions and a high percentage of "don't know" answers. Symbols

that were readily understood were highly pictorial rather than abstract.

In the third phase, groups of subjects from six countries matched each of six

referents against a group of 24 symbols. Different groups received one of

three versions of the symbols being tested for the six referents. (Eighteen of

the symbols merely provided choice alternatives). Each subject matched only

one version of a symbol for each referent. Easterby and Zwaga found that the

matching test allowed them to select a "good" symbol from a set of symbols, but

12
was limited by the quality of the symbol set. Thus, the matching test would

not allow subects to indicate that none of the symbols was particularly effective. As a result, the authors recommended that a matching test be done after

recognition testing has indicated the most "meaningful" symbols.

Both the matching and recognition test data provided valuable insights into

the confusion between symbols, as well as the kinds of alternative answers

given by subjects. These data were instrumental in selecting the set of public

information symbols currently recommended by ISO.

The other major evaluation of the effectiveness of public information symbols

was commissioned by the U.S. Department of Transportation (DoT). First, DoT

sponsored the design of a set of 34 public information signs by the American

Institute of Graphic Artists (AIGA). After compiling a list of existing symbols

for each referent, the AIGA (1974) then designed what they considered to be the

best symbol for a given referent based upon this compiliation.

The list of symbols developed by the AIGA was evaluated by the Franklin Research

Institute. In an interim report, Freedman, Berkowitz, and Gallagher (1976)

used a variety of both paper-and-pencil and performance tests to assess the

symbols. These tests were designed to assess the recognizability of the symbols, elicit confusions, and provide an indication of the relative difficulty

of the symbols. While the initial tests were designed as input to a subsequent,

large-scale testing phase, they did indicate that the symbols varied widely in

initial recognizability. For example, only eleven of the 34 symbols were understood by all subjects.

Following completion of the paper-and-pencil tests of appropriateness, subjects

completed a "walking rally." In this test, subjects followed the symbols to

various locations within a building. Time to arrival and correctness of the

destination were monitored. Freedman and Berkowitz (1977) also administered

matching multiple choice tests at an airport and a subway station, and are in

the process of a large-scale test of the 34 symbols at a variety of transportation facilities.

Preliminary comparison of the paper and pencil data with the field data

indicated few differences in the subjects' responses. Because about 9 symbols

were missed by a large number of subjects, the authors proposed several criteria

for effectiveness. They suggested that symbols which are recognized by 60 percent or fewer people are clearly unacceptable, while those recognized by more

than 80 percent are acceptable. Finally those recognized by 60-85 percent need

some improvement.

These two research projects have assessed the meaningfulness of public

information symbols with large groups of people—people who would likely use

these symbols. Unlike the highway symbol research, no assessment of the speed

of detection was made, nor were the symbol signs directly compared with word

signs. As with automotive/machinery applications, meaningfulness or understandability appears to be the most useful characteristic by which to evaluate public

information symbols, and certainly is the most frequently used by researchers.

13
2 0 5 PRODUCT LABELING SYMBOLS

Another emerging application of symbols is that of product labeling. While

the Canadians, the British, and the Common Market (EEC) have all proposed or adopted standards for warning consumers of potential hazards, there is little

if any research on the effectiveness of these symbols. In addition, several

controversial product labeling symbols have been produced in the U.S. These

include "Mr. Yuk,” produced by the Pittsburgh Poison Control Center, to replace

the skull-and-crossbones to warn children of poisonous substances, and the

lawnmower and CB antenna symbols developed by the Consumer Product Safety Commission (CPSC) to warn consumers of potential accidents. While these symbols

have generated much discussion, only the effectiveness of Mr. Yuk has been

researched. "Mr. Yuk" has been found to be understood by small children as indicating a hazardous ("yuky") substance, although its effectiveness for

adults has not been reported.

One of the few extensive assessments of product labeling symbols was conducted

in Great Britain by Easterby and Hakiel (1977a, 1977b, 1977c). In their first

study, Easterby and Hakiel (1977 a, 1977b) had people design signs to convey

fire, poison, and caustic hazard information. Subjects were provided with a selection of image forms and colors, background colors and shapes, enclosure

shapes and colors, surround shapes and colors, and supporting field colors.

Analysis of the results indicated that red was the preferred color for fire

signs while black was preferred for poison. Both red and black were equally

liked for caustic. Easterby and Hakiel (1977b) commented that these colors

appear to be chosen to indicate the identity of the hazard, and, consequently,

reinforce the function of the image. The stereotypes generated in this series

of studies were used to construct signs for a subsequent study of the

understandability of product-warning signs.

In the final study, Easterby and Hakiel (1977c) evaluated product-labeling

signs by first having students rank-order a set of symbols in terms of their

effectiveness in conveying a given message. This procedure reduced the large

number of symbols found in a compilation of existing symbols to 4 symbols for

each of 3 hazards (fire, poison, and caustic). The ordering experiment

revealed that subjects preferred symbols which describe the hazard (descriptive)

to symbols which prohibited a hazardous action (proscriptive) or prescribed a course of action to avoid a hazard (prescriptive). Furthermore, when there

were several versions of a somewhat similar image, subjects preferred the

visually more complex image to a graphically simplified one. It is not clear,

from the authors' description, whether a complex image is also more graphically

representational

.

The symbols selected from the pilot test were then studied in a nationwide

survey of 4,000 respondents in the U.K. The survey consisted of a recognition

test in which each subject provided meanings for each of 17 signs —5 test signs

and 12 contextual signs that might be found on consumer goods or in public

environments. The five test signs included the poison, caustic, and fire

symbols. All 4,000 respondents judged the 12 context signs, while only 500

respondents judged each variant of each hazard sign.

14
I Analysis of the results indicated that attributes of the sign (image, color

coding, and shape coding) and characteristics of the respondents (age, sex,

household composition, and experience with signs) all influenced the recognizability of the signs. They suggested that symbols which have been extensively simplified from a graphic standpoint do not perform as well as more

complex images — which one can infer, resemble the intended referent more

closely.

Easterby and Hakiel (1977c) concluded, however, that the single factor which

primarily affects recognition performance is image content. Other factors such

as color and observer characteristics are important, but ultimately the understandability of the sign will depend on the symbolic image chosen.

2.6 SAFETY SYMBOLS

Although there do not appear to be any studies which have assessed the

effectiveness of symbols for workplaces, two studies have examined aspects of

safety signs. One (Collins & Pierman, 1979) evaluated the meaningfulness of

fire safety symbols. The other (Laner & Sell, 1960) determined the effectiveness of safety posters. Although Laner and Sell did not assess symbol use,

their work is of interest because it measured the effectiveness of safety

messages directly in terms of changes in unsafe behaviors.

Collins and Pierman (1979) reported an experiment in which they determined the

understandability of 22 fire safety symbols proposed by ISO. They asked 143

subjects to provide a short definition for each symbol. Three judges rated the answers as "correct," "incorrect,” or "no response." In addition a tally was kept of the number and kind of incorrect answers.

The authors found that some symbols such as "fire extinguisher," "no smoking"

and the conventional U.S. "exit" sign were understood by almost all the subjects tested. Yet other symbols such as "blind alley," "do not block" and

"break glass” were understood by less than 20 percent of the subjects. In

addition, several symbols were given a meaning opposite to that which was

intended. Thus, the "no exit" or "blind alley" symbol was interpreted as "exit"

or "safe area" by almost all subjects who gave a definition for this symbol.

Altogether over 95 percent of the subjects either misidentif ied or did not

respond to this particular symbol. Lerner and Collins (1980) confirmed the

fidings of the earlier experiment in a comparison of response methods. Again,

they determined that both "exit" and "no exit" appear to be very difficult to

symbolize effectively.

Collins and Pierman (1979) commented that an instance in which a symbol is given

a meaning opposite to that which is intended is potentially very dangerous.

They recommended that before symbols are adopted, particularly those which

communicate emergency information, their effectiveness must be evaluated. A

safety symbol must be understandable before it can begin to alter behavior and

prevent accidents.

Laner and Sell (1960) examined the effectiveness of safety messages in altering

unsafe behavior. Although safety posters with various sorts of warning messages

15
have typically been used in an effort to stop unsafe acts, their effectiveness

in actually modifying these behaviors has rarely been assessed. Effectiveness

could be measured by studying accident rate reduction directly, except that the

frequency of accidents is so low that the experiment would be inordinately

long. Laner and Sell also rejected the idea of measuring poster effectiveness

in terms of the extent to which a poster could be recognized, remembered, or liked because these measures do not assess actual behavior.

Consequently, Laner and Sell (1960) selected a behavioral measure which could

involve an operation that was potentially dangerous, frequently carried out,

and readily measureable—naraely , the hooking back of chain slings onto a crane hook when not in use. Seven steelworks participated in the experiment in which

posters depicting safe steelworking practices were developed and displayed.

First a baseline of behavior was established over five weeks without poster

display. Then the posters were displayed. Behavior was measured for five

weeks, followed by a lapse of 7 weeks without measurement, concluding with 2 additional weeks of measurement.

Laner and Sell found that the posters had a positive effect in the six test

steelworks (substantial for four of these) but no effect in the seventh, or control steelwork. Furthermore, they noted that the behavior affected by the

posters was at least maintained, if not improved, following the seven week

period in which behavior was not measured. The authors suggested that these

posters were effective either because they acted as perpetual reminders or because they established or reinforced working habits which were selfmaintained. They also found that the increase in safe behavior was greatest in

those shops with low ceilings where the unsafe practice constituted the greatest hazard to personnel. They concluded that posters may be more effective if

the message they carry can be seen to be directly relevant to the situation.

Such a conclusion may be extended to the use of safety symbols as well. In

addition, the use of a behavioral measure—reduction of unsafe acts—is perhaps

the ultimate measure of a sign or symbol’s true effectiveness. Its use should

be explored more for all applications of symbols.

16
3. DEVELOPMENT OF WORKPLACE SAFETY SYMBOL REFERENTS

3 . 1 OVERALL PROCEDURES

The preceding review of research on symbols indicated that researchers typically

begin their evaluative process with an existing set of symbols for specific

referents. These symbols were developed primarily by standards organizations,

graphic designers, and manufacturers, so that the role of the researcher was confined to evaluating these specific images.

The case for evaluating symbols for workplace safety is a bit different,

however, in that there is no single set of existing symbols. Rather, numerous

symbols abound for some referents while few symbols exist for other referents.

Further, the most important set of referents to symbolize has not been determined. Because there are no comprehensive standards in the U.S. for either

referents or symbols for workplace safety signs, the first task in an assessment

of symbols for workplaces is to determine the symbols that are currently used

and the kinds of general situations which require hazard warnings. Secondly,

a list of symbol referents which is broad enough to be applicable to most

workplace situations must be developed. Finally, specific symbols for these

referents must be selected and evaluated experimentally. These three steps

have been followed in the present evaluation of industrial safety symbols.

In this section the various sources used to develop the initial listing of

safety symbol referents are outlined. These sources included site visits, sign

catalogues, and national and international standards. Each of these will be

reviewed in turn. Finally a list of symbol referents based upon all of these sources is presented.

3.2 SITE VISITS

One source of information about current symbol use was observations of practice

at six industrial sites. These industries included: the manufacture and

assembly of heavy equipment engines; the manufacture of ceramic glass; the

final assembly of aircraft; the chemical manufacture of vinyl acetate based

resins; shipbuilding (manufacture, assembly, and repair); and oil refining.

These sites not only provided a range of major industries, activities, and

hazards, but also a spectrum of philosophies in workplace safety practices and

sign use. Consequently, the plant visits provided invaluable background for

this project. Details of the plant visits can be found in Lerner and Collins

(1980).

Each industry has a unique set of major hazards associated with it activities,

such as explosion, extreme heat, caustic chemicals, fire, etc. The most frequently reported injuries, however, often appeared unrelated to these major

threats and were similar from plant to plant. These common injuries included

slips (especially where oil, ice, or chemical substances could be found on the

floor), hand and finger injuries, back injuries, eye injuries, and cuts. Safety

officers often expressed the opinion that workers were cautious about major

hazards and were more likely to be injured where work was routine and repetitious. Somewhat in contradiction, equipment maintenance workers appeared to

17
have especially high injury rates relative to other employees, and this was often attributed to the novel or unfamiliar tasks required of the maintenance

staff. Safety signs seemed to be most frequently related to potential hazards,

or protective gear rather than to common injuries.

In general, the six plants relied heavily upon word signs. Because employees

were believed to be generally literate in English, there was little perceived

requirement for pictographic signs. Nevertheless, the DoT hazard warning

symbols for material transport were in widespread use, as were symbols for

vehicle operating instructions and precautions. One plant, however, did

deliberately use a large number of pictograms, primarily to remind personnel

to wear safety equipment. This plant had a noticeable number of illiterate

employees as well as foreign visitors. Symbols were also believed to be

"eye-catching." In other factories, some specific hazards were symbolized

pictographically . These included "no-smoking" at one site where there were

foreign visitors, and "high noise area—ear protection required" in another

plant. Other than these examples, however, the common practice was to use word signs —often quite lengthy word signs.

In some factories, because the use of color coded areas dominated safety

communication, signs were relatively infrequent. In contrast to signs, this

coding could be spatially precise, indicating the exact location and extent of

the hazardous area. While the prevalance of yellow for hazard indication

suggests the need to adopt a good pictogram indicating a general hazard, the

general use of such a symbol as an alternative or supplement to simple color

coding requires further consideration.

One question addressed during the site visits was the presentation of signs.

In other words, where are they typically located, how are they illuminated,

where are they located with respect to the hazards they represent , and what is

the background against which they are presented? Although such details are expected to vary, there were highly idiosyncratic practices and extreme variability in sign presentation among the sites visited. Even the same message

(such as eye protection required) was located in many different ways: signs were placed on stands in the aisles, or mounted on walls (sometimes well above

eye level and out of the usual visual field), or above entrance ways, or on fixtures and equipment. Often, signs were presented in clusters, rather than

singly. Lighting varied from signs poorly placed in shadow, to ones placed in

bright illumination. Warnings were sometimes placed at entrances, sometimes

located around the workspace, and other times mounted on or near the hazard.

Sometimes warning signs were difficult to see due to clutter, poor maintenance,

or blending into the background color. (In one case the predominant work material was colored yellow to yellow-green, making yellow warning signs obscure).

As a result, no "typical" or "representative" contexts could be identified.

What is a familiar context in one setting appears unusual in another plant, or even in another section of the same plant due to differences in hazards, layout,

and sign usage.

Table 1 indicates the types of generic safety messages that occurred with high

frequency across the various industries. The messages in the table are given

in general form (e.g., restricted admittance), even though the wording of

18
Table 1: Common Generic Messages From Site Visits

Hazards ; General

Electrical

Explosive

Heat

Caustic, acid

Overhead

Noise

Slip/Trip/Watch Your Step

Vehicles

Radiation

Safety and Emergency Gear ;

Eye Protection Required

Hard Hat Required

Foot Protection Required

Caustic-Handling Gear Required

Breathing Gear

First Aid

Emergency Shower

Eye Wash

Fire Alarm

Fire Extinguisher

Fire Hose

Prohibitions ;

No Smoking

No Flames , No Hot Work

Do Not Touch, Keep Away From

Egress, Access ;

Walkway

Exit, Emergency Exit

No Exit

Restricted Admittance

Keep Area Clear

Keep Door Open

Keep Door Closed

19
individual signs may have varied (e.g., authorized personnel only, positively

no admittance, restricted area, do not enter, etc.). While the messages in

table 1 represent commonly occurring and important workplace signs, they should

not be viewed as a complete list, given the limited number of plants visited.

3.3 SIGN CATALOGUES, PUBLICATIONS, AND MANUFACTURERS

In addition to the site visits, the following sources were reviewed for

information on symbol availability: sign catalogues, sign manufacturers,

individual company guidelines, and compilations of pictorial signs (Dreyfuss,

1972; Modley & Myers, 1976).

A list of the most frequent occurring kinds of symbols was compiled from this

review and is given in table 2.

The review of catalogues and publications indicated many common symbols. These

fell into categories such as protective gear, hazard warnings, prohibited

actions and information about fire and safety instructions. In addition, at

least one catalogue offered an extensive list of unusual symbols to fit most

hazards. This report, however, concentrates upon the most frequently occurring

symbols as being representative of current offerings from sign manufacturing

catalogues

.

To assess the demand for symbolic signs, twelve sign manufacturers were asked

for information on sign use, including the most frequently purchased signs, the

most frequently requested symbolic signs, and the perceived demand for symbolic

signs. Although the responses differed greatly in terms of the detail provided,

there seemed to be a feeling that demand for pictorial signs was increasing.

One manufacturer of both written and symbolic signs observed a "very significant

increase in the demand for pictorial signs,” estimating an increase of "about

10 percent or better per year for the past five years." Another company still

produced mainly written messages because it felt some messages could not be

adequately conveyed symbolically. However, it added that this could change if

there were changes in the standards to accommodate symbols. In general, the

responses indicated industry interest in symbolic signs and concern over issues

of standardization and effectiveness. Some sign manufacturers expressed a need

for some form of agreement, but also indicated concern about proprietary rights

for symbols developed by individual companies.

The manufacturers noted that many of the most widely requested pictographic

signs were not safety related (e.g., men, women, handicap access, etc.).

Perhaps the most frequently cited symbolic safety sign was "no smoking.” While

this pictogram varies somewhat, nearly all examples provided used the familiar

image of a burning cigarette with a prohibitory slash through it. Other

frequently occurring symbolic signs included those for protective gear (glasses,

ear protectors, hard hats), flammable hazards, and fire equipment (extinguisher,

hose). Although quantitative information on the use of these signs was not

available, many additional examples of pictograms were provided during the

review of sign catalogues.

20
Table 2. Symbols Typically Available From Sign Catalogues

Prohibition

No smoking

No open flame

Do not enter

Authorized personnel only

Keep out/no trespassing

Do not touch

Protection

Eye protection

Hard hat area Hearing protection/noise area Respirator required/self-contained breathing apparatus

Foot protection required

Hand protection required

Face protection required

Protective clothing required

Protective belt/harness required

Hazards

Radiation area Electric shock/high voltage

Corrosive/ caustic/ acid

Flammable

Fork lift trucks/vehicles

Explosive

Poison

General hazard

Overhead hazard

Slippery surface/danger of falling

Laser

Falling objects/flying objects

Hot surface/danger of burns

Biological hazard

Crushing/ entanglement

Fire

Fire extinguisher

Fire hose and reel

Fire alarm

In case of fire, use stairway

Do not use water to extinguish

Fire exit

Fire hydrant

Information

First aid

Safety shower

Eye wash

Smoking area/smoking permitted

Direction

Exit

Keep door closed

Stretcher

No exit/door blocked

Pedestrian crossing/crosswalk

21
There appears to be only partial correspondence between pictograins that appear

to be most in demand from manufacturers and the written signs most frequently

observed on plant visits. Although the pictograms — for "no smoking," "protective gear," and "fire equipment" — do in fact represent a subset of the most

frequently encountered messages, it is that subset that can be most plainly and

literally represented by a simple picture. Other frequent messages — related

to egress, restricted access, general hazard, doorways — appear less in demand

as pictographic signs. Correspondingly, the graphic representation of these

messages varies much more from company to company. This suggests that developing

an explicit consensus representation for such messages may be an important step

in increasing demand for these symbols. [Such a consensus may arise through the

ANSI Z535 subcommittee on safety symbols which has identified referents and

symbols for further investigation.]

3.4 REVIEW OF SYMBOL STANDARDS

Another source that was reviewed is that of national and international standards

for symbols. As noted earlier, there is no standard in the U.S. for workplace

symbols, although ANSI has recently chartered the Z535.3 Subcommittee on Safety

Symbols. The current OSHA standard does not deal directly with workplace safety

symbols except for those for radiation and biohazard. DoT does use the international (U.N.) standard for symbols for the transport of hazardous materials.

Because these symbols appear upon containers used in factories, they should be

reviewed for consistency with workplace symbols. In addition, individual com- panies and government agencies have developed their own specific symbol standards (see the proposed Air Force Standard, DoT Transportation Symbols, Du Pont

Symbols, and FMC symbols).

At the international level, the International Organization for Standardization

(ISO) TC 80 has drafted a standard (DIS 3864.3) for worker safety symbols which

is currently under consideration. The EEC directive (R/1455) provides a similar set of symbols and referents, as do many other national standards: Great

Britain (BS 5378), Australia (AS-1319), Netherlands (NEW 3011), France (NF

X08=003). See table 3 for a listing of common referents from these international standards. Symbol standards which tend to vary from the ISO norm are those from countries outside Europe. The Canadian Standard (CAN 3-Z321-77)

provides a list of referents and suggested glyph (image) content for some 50

signs related to the occupational environment. Standards from Uruguay and

Bolivia list only 6-8 symbols. Nevertheless a relatively limited set of

common messages emerges from the review of existing standards.

3.5 SYMBOL REFERENTS RECOMMENDED FOR STUDY

After reviewing the wide range of symbol referents collected from sign

catalogues, sign manufacturers, site visits and sign/symbol standards (both

national and international), thirty-three referents were selected for further

experimental study. This list, which is presented in table 4, is based primarily upon the frequency of occurrence of a particular referent in each of the

sources

.

22
Table 3. Symbol Referents Standardized by ISO and the EEC for

European Application

ISO-DIS-3864 .3

Safety Signs

Prohibition Signs

1) Smoking prohibition

2) Fire, open light, and smoking prohibited

3) Thoroughfare prohibited for pedestrians

4) Water as extinguishing agent prohibited

Mandatory Action Signs

5) General mandatory action - exclamation point

6) Eye protection must be worn

7) Respiratory protection must be worn

8) Head protection must be worn

9) Hearing protection must be worn

10) Hand protection must be worn

11) Foot protection must be worn

Warn Signs

12) General warning, caution, danger, risk

13) Caution - risk of fire

14) Caution - risk of explosion

15) Caution - risk of corrosion

16) Caution - toxic risk

17) Caution - risk of electric shock

Information Signs

18) First aid

19) General indication of direction

The EEC Directive (R/1455) adds the following referents:

1) Not drinking water

2) Caution - radioactive material

3) Beware - overhead load

4) Beware - industrial trucks

5) Emergency exit with symbols

Referents added by Australia, British, Dutch or Australian Standards

Caution - laser

Danger - biohazard

Slippery when wet

Danger compressed gas

Danger insufficient clearance

No admittance; no trespassing

Fire extinguisher

Eyewash

Safety shower

Safety stretcher

23
The referents are given in intentionally general form (e.g., "eye protection

required"). At some point, further discrimination among referents may be

required (e.g., "safety glasses," "safety glasses with side shields," "safety

goggles"), depending upon the need to provide information about a specific

hazard or action.

Table 4 is, of necessity, an incomplete list of important workplace safety

messages. Additional referents should be studied as the need arises. The table

contains messages that occur generally across various industries, rather than

one of particular importance in some specific work area. Nevertheless, the

selected items should be widely applicable. This list is a compilation of

symbol referents, or the messages to be communicated, rather than a list of

symbols

.

24
Table 4. Selected List of Symbol Referents for Experimental Study

Access/Egress

:

Prohibition:

Protection:

Hazard

:

Emergency;

Restricted access,

do not enter

Exit

No exit

Emergency

Use stairs in case of fire

No smoking

No open flame

Eye protection

Ear protection

Head protection

Foot protection

Electricity

Fire

Explosion

General Warning

Radiation

Corrosion

Poison

Overhead

Biohazard

Fire extinguisher

Alarm call point

First aid

Safty shower

Eye wash

Respiratory protection

Hand protection

Slippery surface, watch your step

Entanglement

Fork lifts, vehicles

Laser

Falling hazard

Fire hose

25
4.1 4. RESEARCH ON WORKPLACE SYMBOLS

EFFECTIVE SYMBOLS: RESEARCH FOCUS

In sections 2 and 3 research methods and results were reviewed, and a list of

siggested referents for workplace symbols was developed. In developing the

list of symbol referents, it became clear that there was no single set of

existing workplace symbols. The number of images for each referent varied from

2 to over 40. As a result, the assessment of effective symbols for workplace

safety required selecting several plausible symbols for each referent, testing

the understandability of each symbol, and using the most understandable symbol

based upon experimental results. In the following sections a research project

on the understandability of selected workplace safety symbols will be presented

in detail.

4.1.1 Background

To be effective, a symbol must be understood; it must communicate the desired

meaning to all those who encounter it. While understandability is a critically

important criterion by which to evaluate a symbol, it is not the only one. A

symbol must also be detectable at a given distance under specific light levels.

A symbol must be discriminable , or distinguishable from other symbols within a particular set. A symbol must be recognizable, or be remembered and identified

under different circumstances. A symbol must be graphically satisfactory and

command attention. Finally, a symbol must alter behavior in the intended direction and facilitate conformance with the message. A fully effective symbol performs well in each of these areas. Understandability, however, is the key which

unlocks the whole process of conveying a safety message.

As a result, the priority for the research on safety symbols presented in this

paper is the determination of the understandability of several images selected

for each referent. In this way, the most understandable image could be determined for a given referent. Determination of understandability is particularly

critical for workplace safety symbols, where the consequences of failure to

understand could lead to serious injury.

4.1.2 Symbol Selection Procedures

As noted earlier, evaluation of understandability should proceed in several

stages. Where a large number of different images exists for a given referent,

this number must be reduced if further research is to be practical. Use of a ranking procedure is a way of reducing a large set of symbols to a more manageable

set for further study. In a ranking procedure, subjects order a set of images

according to how well they believe that each image conveys the meaning of the

referent. Easterby and Zwaga (1976) followed this procedure with small groups

of subjects in two countries to select three sets of public information symbols.

Similarly, Heard (1974) and Green (1979) had subjects rank order images for

automotive displays and controls according to meaningfulness. Use of a rankordering procedure allows ordered selection of a limited set of symbols for more detailed research. It also suggests that the set of images tested should I

26
be somewhat meaningful. As a result, ISO TC-145-SC1 recommends rank-ordering

as the best procedure for reducing the size of a set of images.

When a large number of images does not exist, or where no existing image

appears to be effective for a particular referent, use of the "production

method" can be valuable. In this method, subjects are given a referent and

asked to draw a symbol which conveys this meaning. Brainard et al. (1961)

used the production method to generate highway sign images. Similarly, Green

(1979) used this method to develop a set of images for automotive controls,

and reported that a subsequent group of subjects was able to identify the

"produced" set of images more accurately than a comparison set. In conjunction

with a graphic artist, the production method is advantageous in producing

a number of images which could be meaningful to a target group. The number can

then be reduced through rank-ordering. Once a set of symbols has been ranked

according to appropriateness for a set of referents, the highest ranked images

must then be evaluated for their understandability to a new, larger group of

subjects. Nevertheless, because of the large number of existing images for

most workplace safety referents, the production method may be needed only at

a later stage where no image has tested well for a particular referent. As a result, the production method was not employed in the present study to generate

symbols for further analysis.

4.2 SPECIFIC IMAGE SELECTION

For the present study the ranking procedure was used to select the final set of

images to be evaluated for each referent. About 30 representatives of the safety

and graphic design communities rank ordered images for each referent in terms

of their appropriateness. Participants rank ordered only the five best images

for each graphic concept, although in some cases as many as 20-30 images were

presented. They then rank ordered graphic concepts to determine which concept

best conveyed the referent. Thus a two stage process of ranking symbolic

images and graphic concepts was used to select one to five images which could

convey each referent effectively.

The set of images selected by the rank order procedure for further experimental

study represent a range of concepts which are presented in table 5. The images

themselves are presented for each referent in the results section. Images that

participants ranked as the best representation for each referent were generally

included. These selections were modified by the following factors: need to

include safety symbols suggested by the International Organization for Standardization (ISO) in the final testing and desire to select as graphically diverse

a set of images as possible. In addition, only one image was selected for

further testing for five referents because these images have already been widely

standardized. These referents include laser, biohazard, radiation, fire extinguisher and standpipe. The final set of images selected represent the following

sorts of general concepts: hazard (abstract or representational); prohibited

actions; hazard consequences; protective gear by itself, on a human form or putting on gear; safety device by itself or in operation; and egress, typically

showing a person and door or some abstract representation. The images selected

also varied along the following dimensions: complexity - simplicity, abstraction - representation, presence - absence of human figure(s), and activity - inactivity. The use of color and surround shape also varied, and was determined

27
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by currently existing standards. Symbols were presented in the form indicated

in the source from which they came.

The goal of the research reported herein is to compare the relative

effectiveness of candidates images selected for each referent. Two studies were conducted: a pilot study to assess the intended procedures and a main

study using these procedures. For the main study, participants were selected

from industrial sites in four geographical locations. For the pilot study,

participants were paid volunteers and students, all of whom were naive to the

workplace. In addition to determining that participants could successfully

follow the experimental procedures, the pilot study data also provided supplementary information on the effects of lack of industrial work experience upon

safety symbol effectiveness. "Effectiveness" includes both understandability

(or ability to provide a correct definition for a symbol) and preference (or

selection of one of a set of symbols as most indicative of a previously given

"meaning” )

.

4.3 METHOD

4.3.1 Experimental Procedure

The experimental study (both pilot and main) consisted of two parts, one

on symbol understandability (part 1) and one on symbol preference (part 2).

In part 1 , participants provided a definition of the meaning of 87 symbols

proposed for workplace safety messages to provide an indication of the relative

understandability of each of the proposed images. In part 2, observers selected

the one of several candidate symbol images for each referent that best conveyed

the safety message to them.

4.3.2 Pilot Experiment

Prior to initiating the main experiment with industrial participants, a pilot

experiment was conducted. The procedure was similar to that of the main

experiment with a few exceptions noted below. Because the pilot participants

were successfully able to follow the experimental procedure, no changes were

required for the main experiment. In addition to testing the experimental

procedures, the pilot experiment served two additional functions. First,

since it used as participants people who did not work in industrial settings,

it provided data for comparison with findings from the workplace population.

These findings may be particularly relevant for new workers, naive to the

workplace, who have been shown to have much higher accident rate than other

workers (National Safety Council, 1979). The second function provided by the

pilot experiment was to decrease the size of the set of symbols tested. In

five cases, four or five symbols for a given referent were initially tested;

on the basis of the pilot results, only three were included in the main

experiment

.

The pilot experiment differed from the final experiment in three major ways:

(a) Participants: The pilot experiment utilized 45 volunteers from the

Gaithersburg, Maryland area and 33 industrial engineering students from the

West Virginia University, for a total of 78 observers. In addition to not

33
working in an industrial setting, this group tended to be younger, and include

more females, than the main experiment. As a result, participants from the

pilot study will be termed "naive" in subsequent pages. (b) Symbols: As

noted four more symbols were included in the pilot. In particular, additional

images were studied for emergency exit, no entry, and exit. Preference data

were also obtained for four images for hearing protection and for respiratory

protection. (c) Procedure: In the main experiment, participants generally

saw only one symbol for each referent message. However, in the pilot study,

the majority of the participants saw all the symbol images for each referent;

this is a more efficient means of data collection, but can have the drawback

of inducing people to try to make distinctions between symbols when in fact

no difference exists. To circumvent this problem, participants were instructed

to respond to each symbol without regard for previously viewed symbols. In

the preference portion of the pilot study, subjects were shown as many as five

symbols, while in the main study a maximum of three images was presented.

In other respects, the pilot procedure was similar to that described below for

the main experiment. The overall similarity of the procedures permits an initial comparison of the perception of safety symbols both by industrial

workers and by those unfamiliar with the industrial workplace.

4.3.3 Industrial Site Participants

For the main study, four groups of industrial participants were selected from

four disparate geographical areas. A total of 222 people participated, 201

males and 21 females. Group 1 consisted of 63 participants (62 M, 1 F) from

the Phoenix, Arizona area. These individuals were drawn from a power company

and a professional safety training class and represented the following types of

occupations: electrician, electrical supervisor, electrical apprentice or helper, foreman, truck driver, cable splicer, welder, fire fighter, technician,

and similar occupations. Of these 63 participants, 23 viewed all 87 symbols

during part 1. Group 2 consisted of 67 participants from 10 industrial sites

in the West Virginia, western Pennsylvania and western Maryland area. These

participants, of whom 50 were male and 17 female, were drawn from a variety of

industries including warehousing, candy production, floor covering manufacture,

glass production, aluminum reduction, aircraft production, aircraft assembly,

mobile crane, and manufacture of graphite electrodes. Group 3 consisted of 28

participants (27 male, one female) from a paper production plant near Washington, D.C. These participants were primarily first line supervisors.

Group 4 consisted of 64 participants, 62 male and 2 female, from a home appliance manufacturer in Ohio and represented the following occupations: quality

control inspectors, assemblers, repair, and maintenance. Industrial participants generally ranged in age from 20 to about 60 with an average age of around

35. At least two individuals were Spanish speaking.

4.3.4 Symbols Tested

In part 1 , each participant provided a definition of the meaning of each image

presented. In part 2 (preference), participants selected the image that best

conveyed a particular safety message. Participants viewed only one image for

34
a particular message, except for 23 people in group I. Although these individuals saw all 87 images, they were instructed to define each image individually

without reference to prior images. The authors hypothesized that there would

be no difference in the percentage of correct definitions or of percentage of

preference among the candidate symbolic images studied for each message.

A total of 87 images for the 33 referents was presented in part 1 (understandability) to the industrial participants. Only 79 images were presented in the preference portion, because for eight referents only one image

had been assessed in part 1. The total set of 87 images included 16 safety

symbols proposed by ISO TC 80 (1979) and four firesafety symbols proposed by

ISO TC 21 (1978). All images studied are presented in figures 1-31.

4.3.5 Stimulus Material

Each symbol was initially silk screened onto a 30 cm x 30 cm ( 1

' x 1’) placard.

Color slides were then photographed individually from each placard. Finally,

symbols intended for use in the preference portion were photographed as a set

for each referent. These symbols were labeled A, B, or C to facilitate choice

by the observers. In general, slides or placards were used as convenient for

the understandability portion of the experiment except for Group 4 where only

individual slides were used. Slides of the symbol sets for each referent were

used in part 2.

4.3.6 Procedure

An experimental session consisted of the following set of events: a) participants read and signed consent forms outlining the safety and Privacy Act

information; b) instructions for the understandability portion were given,

along with a practice example; c) participants provided definitions on the

understandability of the images; d) instructions for the preference portion

were given; e) participants selected preferred images; f) participants were

debriefed. The entire session including one break required about 45 minutes.

Observers participated in groups of 4-25 in a variety of facilities. The

symbols were presented in one of three random orders. Whenever possible participants from a given site were divided into three subgroupings. Each group

received a different random order of symbols in part 1 , and a different random

order of referents in part 2 to control for possible order effects. In part

1, symbols were presented at a rather slow rate (about 30 s per symbol—or when everyone had finished responding). Participants were asked to "give a short definition of each workplace safety symbol that we present to you."

They were instructed to "define what the image means," not merely "report what

it represents." As an example they were shown the "knife and fork" symbol and

told that it meant "restaurant" or "place to eat" not just knife and fork. In

part 2, participants were told the meaning of each set of symbols and were asked

to "indicate which one of the symbols you feel is best at communicating that

meaning" and why. About 30 s to 60 s were allowed per referent. Complete

instructions to the participants are presented in appendix A. After completion

of part 2, observers were debriefed about the purpose of the experiment.

35
4.3,7 Scoring of Response Protocols

Answers for the participants in part 1 (Understandability) were scored as correct, partially correct, incorrect, or no answer. Three judges rated each

answer. The judges initially discussed criteria for each scoring category and

then independently scored all answers. Criteria included an assessment of the

participant’s knowledge of the hazard and possible precautions to take. Where

the judges did not have initial agreement, they then resolved all discrepancies.

In the few cases where discrepancies existed, discrepancies were resolved by

further discussion among the judges. Where resolution was not achieved, the

majority opinion was adopted. In some cases, discussed in detail in section 5,

special response categories were also identified separately.

Performance of the participants in providing definitions are reported for four

scoring categories: Wrong, (X), No Answer, (N), Correct, (C), and Lenient - a category comprised of fully and partially correct answers. Answers were con- sidered partial if they: failed to indicate a prescribed action (e.g., "hard

hat" rather than "wear a hard hat"); were too general, or too narrow, or failed

to indicate the full meaning of the symbol ("don't discard lighted cigarettes"

for "no smoking"). In addition, wrong answers were placed into two categories;

wrong, where the answer was simply incorrect, and critical confusion, where

the answer indicated a meaning opposite to that intended.

36
5. RESULTS AND DISCUSSION

5.1 GENERAL

The results of the experiment are summarized in figures 1-31. All figures

present both understandability and preference data for the industrial participants, with similar data for the non-industrial participants included for

comparison. The understandability portion of the figures indicates the percent

of answers that were fully correct, (C) the percent that were either fully and

partially correct (C+P) also termed leniently scored, the percent wrong (X),

and the percent no answer (N). The results of chi-square tests (discussed

below) indicate whether the distribution of answers, as correct, partially

correct, or wrong, differed among the various symbols for each referent.

The preference portion of the figure indicates the percent of participants

indicating a preference for each of the candidate symbols for a given referent. The results of statistical tests (see below) indicate whether there is

any statistically significant difference in the number of participants prefering each alternative. The percentages of participants preferring each alternative symbol for a given referent generally do not sum to one hundred percent.

This is because some participants indicated no preference, or did not put down

any answer, despite the forced-choice instructions. Although generally small,

the percent of participants not indicating a preference exceeded 5 percent in

six cases (all 5-10 percent, except for General Warning where it exceeded

30 percent).

To evaluate the understandability data for the industrial participants for all

symbols for a referent, chi-square contingency tests of the differences in

response distribution for the several symbols for a given referent were used

to compare the distribution of answers across the categories "correct”, "lenient" (C+P), or "not correct" (wrong answer or no answer). In some cases, where

expected cell frequencies were small (less than five), partially correct and not

correct categories were combined; these cases are identifiable by the reduced

number of degrees of freedom, indicated in the figures. To evaluate the preference for each alternative symbol, chi-square tests were used to compare the

distribution of choices across the three alternatives. Where only two alternatives were presented, a binomial test, using the normal approximation, was employed, and a Z-score, rather than a chi-square, appears in the table. As

the figures indicate, there were significant differences in preference among

symbols for all but two referents (General Warning and Eyewash).

Before discussing each set of symbols in detail, some general conclusions can

be made about the results. First, despite the pre-selection of symbols based on expert rankings, there were often wide differences in the degree to which

different symbols communicated the same message. The Corrosion Hazard and

Entanglement Hazard Symbols provide some examples. Secondly, some referent

messages appear much more difficult to convey than others. In some cases no alternative was well understood (e.g. No Exit, only 18-59 percent at least

partially correct) while in other cases, all alternatives were well understood

(e.g. Eye Protection, 90-100 percent for at least partially correct). In general, protective gear messages appear relatively easy to indicate symbolically.

37
Understandability and preference were sometimes dissociated. Where the

understandability data indicated a clearly superior symbol (eg., Safety Shower

Location), that alternative was usually preferred. Yet, there was occasionally

a strong preference for a particular symbol even where little difference in the

understandability measure existed; infrequently, a strongly preferred alternative

was the most poorly understood (eg. Foot Protection Required).

In general, industrial and non-industrial participants yielded similar patterns

of results (due to differences in symbol sets and procedure, no formal statistical comparisons were made). Some exceptions are noted in the following

sections

.

Partially correct and incorrect answers were analyzed to reveal common errors

for each symbol. These results are summarized in table 1 of appendix C. The

preference answers were reviewed to find common reasons for preferring or disliking each symbol. These findings are summarized in table 2 of appendix C.

5.2 DISCUSSION OF SPECIFIC FINDINGS

5.2.1 Overview

Figures 1 through 31 present detailed analyses of the responses for both groups

of subjects to each symbol. These not only include a breakdown of the understandability and preference measures for each symbol, but also a summary of the

common errors and preference reasons. Data for percentage fully correct

responses, percentage correct plus partial (lenient category), percentage

wrong, and percentage no answeres are presented, along with the percentage of a particular subset of answers where these were of additional interest. The most

frequently occurring wrong answers for industrial subjects are presented, for

those wrong answers which occurred more than once for a particular image. The

percentage of "critical confusions” for industrial subjects is also indicated

on this tabulation. These are derived from the number of wrong answers given

by all subjects responding to a specific image, and are defined as an opposite-

-to-correct or seriously inappropriate answer. The chi-square statistics for

industrial subjects are also presented for both understandability and preference

data. The lower portion of the figures present percentage preference data for

both groups of subjects, and the most frequently occurring preference reasons

for industrial subjects. While the stated reasons for preferences are ofen

informative, some subjects had considerable difficulty expressing their reasons;

"no reason" was often the most frequently occuring response.

The data presented in figures 1-31 are discussed in detail in the following

sections. Comparisons are made between images for a given referent and for

images within a generic category (such as hazard warnings or protective gear

requirements). Comparisons are also made between industrial and naive groups

of subjects. In the discussion, reference is made to the ISO criterion cutoff. ISO (referenced in AS 2342, 1980) proposed a level of 85 percent correct

responses on an understandability test as the cut-off between acceptable and

non-acceptable symbols. It also proposed that symbols for which five percent

or more critical confusions are elicited are not acceptable, regardless of the , percentage of correct answers. The data in the following pages are discussed

38
in terms of their performance related to these ISO criteria. These rriter . themselves are not addressed, although there may well be conditions i i which

the severity of the indicated hazard could mean that a cut-off of 85 percent

is too low. In this report the criteria are used as an arbitrary point for

discussion purposes only. Further research is needed to determine whether

these criteria are the most appropriate.

5.2.2 Hazard Warning Messages

Figures 1-12 all concern referents that indicate hazard warnings. These will

be considered first.

Figure 1 presents the data obtained for three images for electrical hazard.

Image C, of hand and wire, emerges as the best understood and most preferred

image for both industrial and naive participants. The understandability of

image C is even greater if answers involving wires are included in the correct

plus partial category increasing this from 74.4 to 96.5 percent correct.

Answers involving electric wires were identified separately for the main experiment because of some concern that image C too explicitly referred to exposed

electrical wires and the actual hazard might occur in some other form. Even

without consideration of such answers however, image C is significantly more

understandable than image A, the internationally proposed symbol for electrical

hazards. In addition, symbol A received a number of wrong answers unrelated to

electrical hazards, including curved or crooked road, slippery floor, and danger, or go below. Wrong answers for image B were restricted to ideas about

lightning and for image C to ideas about hand danger.

The preference data for all participants indicates a clear preference for

image C because of the hand and wire and explicit rendition of electric hazards

to people. Image A was chosen because of its color and shape while image B was believed to "look like electricity." Image C is somewhat unusual in that

"no reason" for this choice is the third, rather than first most frequently

occurring answer. Participants remarked on the graphic characteristics of

image C and its depiction of hazard as the primary reason for their choices.

Image C thus emerged as the most successful depiction of electrical hazard, of

the three images studied.

Figure 2 presents the data obtained for three images for explosion hazard.

These images varied in terms of their abstractness as well as in color and sur- round shape. Chi square tests for industrial personnel revealed a significant

difference in the understandability data for the three images, with image B

having the highest percentage of fully and partially correct answers. Naive

participants provided more fully correct answers for images B and C but were generally quite similar for the lenient (correct plus partial) category. Wrong answers for the three images included ideas of flammability, danger, and broken

glass for images A and C, electricity for image B, and flying stones for image

C. Image A also received answers such as "star" that were unrelated to any

sort of hazard. Both images B and C were understood by more than 80 percent

of the subjects if lenient scoring criteria are used.

39
Figure 1. Danger, electrical hazard

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88 N = 86

Correct - C 47.9 62.5 69.8

Lenient - C+P 63.9 77.3 96.5

Wrong - X 29.8 13.6 3.49

No Answer - N 6.4 9.1 0 l.ll 2.3 1 22.

1

1

X

2 (Chi square) X

2 =39.78, df=4, pC.001

Naive N = 53 2 N = 54 N = 61

C 28.3 61.1 86.9 C+P 37.7 66.7 95.1

X 54.7 31.5 4.9

N 7.5 1.8 0.0

Wrong lightning lightning hand danger Answers curves crooked road

danger below

slippery floor

go to lower level

PREFERENCE DATA

Industrial 9.0% 11.3% 79.3%

X2 X

2 =2 13.39, df =2 , p<.001

Naive 6.4% 3.3% 89.8%

Reasons no reason no reason, hand 4 wire

color & shape looks like wire shows more noticeable electricity electrical

large & clear hazard

no reason

better graphics

explicit

1 Includes answers specific to electric wires - included in C&P category.

2 Forty-five subjects saw all symbols.

40
Figure 2. Danger, explosive hazard

A B C

UNDERSTANDABILITY DATA

Industrial N = 88 N = 94 N = 86

C 56.8% 64.9% 54.6%

C+P 71.6% 88 . 3% 82.5%

X 15.9 7.5 9.3 N 12.5 4.3 8.1

X2 X

2 =l 1.6, 4df , p<.05

Naive N = 54 N = 53 N = 61

C 55.6% 83.0% 65.6%

C+P 66.7% 88.7% 90.2%

X 29.6% 11.3% 8.2%

N 3.7% 0 1.6%

Wrong fire, combustible flammable, fires breakable

,

Answers beware of broken glass high tension shattered

star electricity glass

danger, disaster area danger, hazard flying stone, area gravel

PREFERENCE DATA

Industrial 4.7% 38.3% 56.1%

X

2 X

2 =91 .43, df =2 , p<.001

Naive 1.3% 39.7% 57.7%

Reasons no reason no reason. no reason, more noticeable looks more like looks more like

explosion explosion

clearer, more vivid debris

color shape, color

imply caution

more easily

unde rstood

best sign

41
Both groups of participants expressed a preference for C, the ISO proposed image

Reasons for the selection included the idea that it looked more like an explosion with flying debris, its background shape and color implied caution,

and it was the best, most understandable sign. Image B was selected because

it looked more like an explosion, was clearer, more vivid and was red, while

image A was claimed to be more noticeable. For all three images, however, "no

reason" was the most frequently occurring answer for the preference choice.

Figure 3 presents three images for flammable hazard. All images tested below

85 percent correct for all subjects, and no significant differences between

the three images emerged. The reasons for the poor performance can be seen from the wrong answers, which generally suggest the idea that fire or high

temperatures are present or permitted in the area. These symbols do not seem

to convey successfully the idea of combustibility—that something could ignite,

rather than that something is burning. In particular, image B conveyed the idea

of fire permitted to six percent of those studied—an example of a "critical

confusion.

These data suggest the need to improve the currently proposed images for

combustible hazards to increase the awareness of possible flammability rather

than presence of an actual fire. Use of red color, as in image C, does not

appear to do this, nor does the triangle or yellow color in images A and B.

Training people on the meaning of a flammable hazard symbol may be needed to

convey the idea that something could burn. The preference data are about

evenly split between images B and C, with clarity, color and visual rendition

given as primary preference reasons. No symbolic image emerges as particularly

successful in communicating the idea of flammability. In the absence of a successful image for flammability hazards, users might consider the use of a prohibition symbol, such as "No Open Flame" or "No Smoking."

Figure 4 presents the data for three images for corrosion. The pattern of

responses for both naive and industrial subjects was very similar. Image B,

the bandaged hand, was clearly not understood by the majority of the subjects.

Image A, the ISO proposed image, was the only image performing above 85 percent

for leniently scored data. (A also received very few wrong answers.) For image

B, 45 percent of the answers were related to first aid or bandaged hands.

Turning or stopping, pinch points, danger and hand injuries were also frequently

given answers. For image C, 79 percent of the answers referred to first aid

or emergency hand wash while sharp cutting machinery was also given as a wrong

answer. Image B was not only not understood, it was often perceived as emergency aid rather than a hazard. On the other hand, only two percent of the

answers to image A were related to emergency aid.

The preference data for all subjects indicated a strong preference for image A

as the b^st depiction of corrosion hazard. Reasons included that it was clearer

and more believable, showed consequences, showed two types of hazard, portrayed

chemicals dripping, and its color (yellow) and shape (triangle). Image C was selected because it showed a larger concentration of effect and was more descrip

tive. No subject expressed a preference for image B. Image A thus emerged as the most understandable and preferred of the images tested for corrosion as well

as having the least number of opposite and potentially hazardous confusions.

42
Figure 3. Danger, flammable

ABC

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86 N = 88

C 41.5% 41.9% 52.3%

C+P 70.2 65.2 65.9%

X 19.1 34.9 31.8

N 10.6 0 2.3

X2 X2 =6.68, df =4 , NS (not eiignif icant

)

Naive N = 53 N = 61 N = 54

C 34.0% 41.9% 52.3%

C+P 64.2% 65.2 65.9%

X 30.2 45.9 29.6

N 5.7 0 0

Wrong fire present in area, fire present fire, open

Answers hot, high temperature in area, flames

smoking area fire extinguisher extreme heat

Confusions fires permitted - watch for fire

76.6%

PREFERENCE DATA

Industrial 5.4% 50.9% 41.9%

X2 X2 =78.72, df=2 , p<.001

Naive 5.1% 44.9% 48.7%

Reasons no reason no reason, no reason

clearer, easier to red color

distinguish good visual

color & shape rendition

looks like fire clearer

should be red

43
Figure 4. Corrosion hazard

UNDERSTANDABILITY

ABCDATA

Industrial N = 88 N = 86 N = 94

C 78.4 1.2 69.1 C+P 90.9 18.6 80.8

X 3.4 63.9 13.8

N 5.7 17.4 5.3

X2 X2 =137 . 58 , df =4 , p<.001

Naive N = 54 N = 61 N = 53

C 74.1 6.6 75.5

C+P 92.6 18.1 83.0

X 5.6 73.8 16.9

N 1.9 8.2 0

Wrong Danger , pinch caution sharp Answers points cutting

Turn (left, right)

danger, think

stop, halt

machinery

Confusions *First aid, hand wash *First Aid *emergency hand

2% bandaged hand. wash area 4% injuries 73% *f irst aid - 3%

PREFERENCE DATA

Industrial 78.2 1.8 17.8

X2 X

2 =220 . 96 , df =2 , pC.001

Naive 64.1 0 32.0

Reasons no reason no reason no reason

clearer, more believ- larger concenable tration of

shows consequences effect

color & shape more descriptwo types of hazard

chemicals dripping

tive

44
Figure 5 presents the data obtained for two images studied for poison. Not

only was image A, "Mr. Yuk" , not understood, many of the answers were frivolous

or inappropriate. Ten percent, for example, were related to unhappy people or unpleasant areas. While image B, the skull and crossbones, was correctly identified by only 76 percent of those tested, wrong answers referred to danger or death rather than "cafeteria ahead" or "have an unhappy day." "Mr. Yuk", however, is one image for which the naive participants performed substantially

better (52 percent vs. 20 percent for leniently scored data) than the industrial

participants. These participants were generally younger and may have seen some

of the television and other advertising aimed at teaching children that

"Mr. Yuk" means poison. Nevertheless, image B was still identified correctly

by more of these participants (82 percent vs. 52 percent). Neither of the two

poison images reaches the 85 percent criterion cutoff, unless the general

references to danger and death are counted as correct for image B.

The preference choice was clearly for image B, although the naive participants

expressed a slightly greater liking for Mr. Yuk than did the industrial participants (20 percent vs. four percent). The only reason given for selecting

Mr. Yuk is that this symbol would be more clearly recognized by children (not

a significant concern for industrial conditions). The skull and crossbones was

selected because it was widely known and recognized, presented the idea of death

and skeletons, had more impact, and depicted poison. Further consideration of

"Mr. Yuk" for industrial participants appears inappropriate based upon the

significant understandability and preference data for the skull and crossbones

presented in figure 5.

Figure 6 presents the data for three images for entanglement. These images

varied widely in understandability, with only image C, hand and gears, performing above 85 percent for leniently scored data for both groups of participants.

Using lenient criteria, image A also scored above criterion levels for naive

but not industrial participants. In terms of wrong answers, a greater percentage of people gave "machinery in use" as an answer for image A than for image C

(15 percent vs. one percent). Image B was poorly understood for all participants with wrong answers related to movement, explosives, machinery in use,

intersections and the like. The presence of the hand in image C appears to convey the message of "machine hazard" rather than simply "machine in operation."

The preference data strongly favored image C because it showed the consequences,

was easy to visualize, and looked painful. Image A was selected because it

showed open gearing, while no reasons were given for selecting image B. For

image C, "shows consequences" occurs even more frequently than "no reason."

For entanglement hazards, then, image C, hand in gears, emerged as the most

well understood and most preferred for all participants tested.

Figure 7 presents data for three images for slip hazards. All images performed

above the 85 percent cut-off, regardless of scoring criterion (lenient or strict) for industrial personnel. (Only image A falls below this for naive subjects). Furthermore, there was no significant difference between the images in

terms of understandability for industrial participants. Wrong answers for image

45
Figure o. Danger, poison

A B

UNDERSTANDABILITY DATA

Industrial N = 86 N = 88

C 13.9% 75.0%

C+P 19.7 76.1 X 43.0 21.6

N 37.9 2.3

X

2 2=62.87, df=l, p<.001

Naive N = 61 N = 54

C 45.9% 75.9%

C+P 52.5 81.5

X 45.9 18.5

N 1.6 0

Wrong gas, fumes in area danger

Answers caution, bad taste, bad food

unhappy people, unpleasant

area danger, caution

hazard, vomit area Confusions *sraile, good attitude 2%

PREFERENCE DATA

Industrial 4.5% 94.1%

X

2 z=6.20, pC.001

Naive 20.5% 79 . 5%

Reasons no reason no reason

more clearly recognized by widely know & children recognized

idea of death,

skeleton

best, more impact

shows poison

46
Figure 6. Danger, entanglement hazard

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86 N = 88

C 67.0% 30.2% 77.3%

C+P 82.9 36.2 94.3

X 15.9 33.7 1.1 N 1.1 30.2 4.5

X2 X2 =81 .96, df =4 , pC.001

Naive N = 53 N = 61 N = 54

C 45.3% 9.8% 63.0%

C+P 90.6 19.6 94.5

X 9.4 63.9 5.6

N 0.0 16.4 0.0

Wrong Machinery in use, 15% turning rolling machinery area Answers objects

think, danger,

1%

caution

intersection, no U

turn explosives in use going both ways

moving fast turn around

machines in area protective eye gear

needed

PREFERENCE DATA

Industrial 11.5% 5.9% 81.8%

X

2 X2 =240 . 39 , df=2 , p<.001

Naive 10.2% 0 88.5%

Reasons no reason no reason show consequenshows open gearing ces no reason

easy to visualize

looks painful

47
Figure 7. Danger of slipping

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88 N = 86

C 94.2% 93.2% 87.2%

C+P 94.2 94.2 90.4

X 5.8 3.4 6.4 N 0 2.3 3.2

X2 x2=3.87, df=2, (non-sigrtif icant)

Naive N = 61 N = 54 N = 53

C 77.0% 81.5% 94.3%

C+P 81.9 90.8 96.2

X 14.8 9.2 3.8

N 3.3 0.0 0.0

Wrong wear boots housekeeping, keep dock, ledge area Answers snake may bite area clear

PREFERENCE DATA

Industrial 9.5% 37.8% 52.7%

X2 X2 =64 . 3 , df =2 , pC.001

Naive 10.2% 33.3% 56.4%

Reasons no reason no reason no reason

shows hazard person falling shows falling

clear, more under- clearest

standable

48
A included "wear boots" and "snake may bite," for image B, "keep area clear,"

and image C, "dock" or "ledge area." None of these answers included serious

confusions or opposite meanings.

Consideration of the preference data revealed a strong preference for version C,

because it showed the whole body falling and was the clearest. Despite good

understandability , only about 10 percent of those responding chose image A,

stating that it showed the hazard. Image B was selected because it showed the

idea of falling and was more understandable. Image C thus appears to be the

best portrayal of "slip" hazard based upon the preference and understandability

data although none of the three images elicited any critical confusions.

Data for slip hazard given in figure 7 must be considered in conjunction with

those given in figure 8 for tripping and falling hazards. The very poor

performance of image B of figure 8 was due to a large number of answers related

to slips. About 70 percent of those responding believed that image B represented a slipping hazard. Image B of fall hazard (figure 8) and image C of slip

hazard (figure 7), which differ only in the presence of a horizontal surface in

image C, both successfully conveyed the message of "slip" to 70 to 90 percent

of those tested. Image A of figure 8 conveyed the idea of tripping and falling

along with obstructions in the path of travel. Image C conveyed the idea of

fall from elevation to 72 percent of those responding and the idea of falling

over to another 20 percent. It did not convey the idea of tripping over an object, however. Consideration of the understandability data, including wrong

answers, for figures 7 and 8, suggests the need for three separate referents

slipping hazard due to slick surfaces, tripping hazard due to obstructions in

the path of travel, and falling hazard due to sudden changes in elevation.

The preference data for the fall symbols indicated a preference for B because

it showed the person falling and was clearest, although the same reasons were

also given for C. A was selected for "no reason" and because it showed the

hazard. Because at least two ideas were clearly being responded to here, it

is a bit difficult to conclude that one image represents tripping and falling

better than another. Participants, whether naive or informed, clearly differentiated between tripping, falling, and slipping as three unique ideas and images.

Subsequent research should separate these three referents and determine if

three distinct images can uniquely convey the messages of slip, trip, and

fall.

Figure 9 presents data for three images for fork lift truck hazard. Images A

and C tested above the 85 percent criterion level for both naive and informed

subjects for leniently scored data. Image B, which performed more poorly,

conveyed ideas about men working, suggesting that the forklift driver should

watch out for people working. The presence of two figures in the image caused

confusion about what the hazard really is —the person working or the forklift

truck moving. Other comments were related to the work done by the forklift.

Image A received few wrong answers, all related to the need to use or not use

a forklift, while image C received more wrong answers, again related primarily

to forklift operation. In general, naive participants performed somewhat more

poorly perhaps due to their lack of familiarity with forklift trucks.

49
Figure 8 Danger of tripping or falling

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86 N = 88

C 69.8% 14.9% 20.4%

C+P 90.7 17.0 92.0

X 6.4 6.4 2.3

N 6.4 6.4 5.7 slip 3.5 slip 70% fall 71.6%

X2 X

2 =127 .01 df=4 , p<.001

Naive N = 61 N = 53 N = 54

C 78.7% 26.4% 51.8%

C+P 91.8 28.3 87.0

X 8.2 15.1 13.0

N 0.0 0.0 slip = 56.6% 0.0

Wrong boots safety hazard, danger area Answers shoes required

PREFERENCE DATA

Industrial 20.3% 50.5% 25.2%

X

2 X2 =36 . 37 , df=2 , p<.001

Naive 14.1% 43.6% 38.5%

Reasons no reason no reason no reason

shows hazard person falling shows falling

clearer, more under- clearest

standable

50
Figure 9. Danger, fork lift operating in area

A B C

UNDERSTANDAB I LI TY DATA

Industrial N = 94 N = 88 N = 86

C 83.0% 54.5% 72.1%

C+P 96.8 81.8 93.0

X 2.12 15.91 6.98

N 1.06 2.27 0 slip 3.5 slip 70% fall 71.6%

X

2 X2 =21 .02 df=4, p<.001

Naive N = 53 N = 54 N = 61

C 64.2% 42.6% 67.2 % C+P 92.5 81.5 88.5 X 1.9 1.9 11.5

Wrong handle, don't handle watch for men working forks in improper

Answers with fork lift dangerous work area

use truck lift

location

PREFERENCE DATA

Industrial 59.7 % 31.1% 8.3%

X2 X2=89.00, df=2 , p<.001

Naive 57.7% 34.6% 7.7%

Reasons no reason no reason no reason

clearest, most under- red means danger easiest to standable most informative understand

person & truck

looks more like fork

lift

shape & color

51
Image A was most preferred by both groups of participants. They stated that

it was clearest and most understandable, showed a person and a truck, looked

more like a forklift and was the right background shape (triangle) and color

(yellow). Image B was selected because it was red and was most informative

(despite the fact that participants did not understand it as well) . Image C was chosen least frequently, although some participants claimed it was the

easiest to understand. Image A, of a person driving a fork lift, emerges as the best understood and most frequently preferred, although image C was also

well understood.

Figure 10 presents data for three images for overhead hazard. These images

varied from very abstract (A) to representational (of the hazard - B) , to a rendition of the consequences of the hazard (C). Image A, the most abstract

image, was not understood, either by naive or industrial participants. For

image B, 60 percent of those tested identified it as overhead hazard with

about another 35 percent identifying it specifically as crane load or broken

cable. Similarly, image C conveyed the idea of wear hard hat (to 44 percent

of the participants) almost as well as overhead hazard (51 percent). Images B

and C thus appeared to be providing very specific meanings directly related to

the hazard or action depicted. The more abstract, general image, A, was even

less successful, conveying ideas of yield, caution, hole, objects on floor,

fallout shelter, hazardous materials, radiation, dark area, and a host of

other inappropriate responses.

Participants expressed a strong preference for image B saying that it

represented an overhead hazard and was clearest. Image C was the second choice

because it made the consequences clear with an object falling on a person.

Image A was selected by only 0.5 percent of the subjects.

Overhead hazard appears to be another referent for which the intended meaning

must be more clearly defined. A broken crane load is perceived as just that,

not as a more general overhead hazard. Image C effectively conveys the message

of wear hard hat but may not warn of moving, heavy loads overhead, for which a hard hat would be insufficient protection. The two images, B and C, appear

to present two distinguishable messages, while image A does not communicate,

much, if any useful hazard warning information.

Figure 11 presents data on two images for general warning. Neither image is

well understood, with B being particularly unsuccessful (eight percent lenient

category). The naive participants did appear to understand A somewhat better

(79 percent versus 56 percent, lenient) than did the industrial participants for

reasons that are not clear. Wrong answers for A included ideas such as stop,

ballpark, excitement, overhead operation, and information. Wrong answers for

B indicated that participants associated it with crossings, intersections, and

prohibited actions (do not enter, do not yield, do not proceed, and do not

touch). Although A was preferred to B, at least 30 percent of those tested

chose neither image, and where a choice was made, the most frequently occurring

comment indicated that both images were poor. The exclamation point in A was seen as providing some idea of "pay attention" while the X in B indicated

"stop". Nevertheless, if a general warning symbol is believed to be useful,

some form of further training on the meaning of either A or B would be required.

52
A B C

UNDERSTANDABILITY DATA

Informed N = 88 N = 94 N = 86

C 2.3% 52.1% 51.2%

C+P 3.4 59.5 95.4

X 52.3 5.3 1.2 N 44.3 0 3.5 crane load = 35.1%

X2 X

2 =2 17.77, df=4 , p<.001

Naive N = 54 N = 53 N = 61

C 5.6% 67.9% 54.1%

C+P 5.6 73.6% 90.2

X 85.2 17.0% 8.2

N 9.2 0.0 1.6 crane load=9.4%

Wrong yield broken cable, bad strap Answers danger, caution area going down, hole

something on floor

toxic, hazardous

radiation

limited visibility

fallout shelter

PREFERENCE DATA

Industrial 0.5 69.6 30.0

X2 X2 = 160. 34 , df=2 , pC.001

Naive 1.3 52.6 44.9

Reasons simple no reason no reason

• shows overhead hazard object falling on depicts hazard better person

clearest, easy to understand consequences clear

more understandable

53
Figure 11. General warning

A B

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88

C 51.1% 6.8%

C+P 56.4 7.9

X 13.7 71.6 N 29.8 20.5

X2 Z=40.55, df=l, pC.OOl

Naive N = 53 N = 54

C 62.3% 5.6 C+P 79.3 7.5

X 15.1 90.7

N 5.7 1.8

Wrong stop restricted area, keep out, no Answers ballpark entry

excitement area dangerous crossing, intersection

overhead in operation dead end, no access, right of way

informat ion/ exclamation do not yield

area do not proceed, cross unsafe, do not touch

do not

PREFERENCE DATA

Industrial 40.1% 29.7%

X2 Z = 1.85, N.S.

Naive 44.9% 30.8%

Reasons no reason no reason neither one both bad

easily understood indicates stop

exclamation point more understandable

54
Image A appears to be a somewhat more promising choice in that 56 percent

understood it versus the eight percent (lenient scoring) who understood B.

Yet, neither symbol is particularly successful in communicating the idea of

"watch out, pay attention, and general hazard warning." In fact, the skull

and crossbones image of figure 5 is almost as effective at conveying the idea

of possible danger or death.

Figure 12 presents understandability data for three referents - radiation (A)

,

laser (B) and biohazard (C)» Each of these has been standardized at least

briefly by OSHA, while the radiation symbol has been in use for many years.

The data however, indicate that none of these symbols reach a criterion level

of 85 percent understandability, with laser and biohazard being at or below 25

percent. Wrong answers for radiation included numerous confusions about fans,

blades, moving parts, alarm, and noise as well as a critical confusion with

fallout shelter for three percent of the industrial participants, and 11 percent of the naive subjects. This is a serious misidentif ication which could

lead people into, instead of away from the hazard. It may be due to the current similarity of colors between the radiation and fallout shelter symbols.

ANSI Z53 recently standardized (1980) the radiation symbol as yellow and black,

with black replacing the magenta previously used for radiation. The fallout

shelter symbol is also a yellow and black abstract 3-part symbol (within a circular surround). These critical confusions associated with the radiation

symbol are potentially serious, because the air raid symbol /fallout shelter

symbol is intended for public information, and because the radiation symbol is

used on consumer products such as smoke detectors and fire alarms.

The laser and biohazard symbols were even less well understood than the

radiation symbol. The biohazard symbol was deliberately designed not to be

meaningful (3aldwin and Runkle, 1967). It was felt that a unique but memorable

symbol could be taught and used to indicate situations where warning of potential infection hazards is needed. Certainly the present data reconfirm those

of Baldwin and Runkle indicating that the symbol does not communicate meaningful information. If this symbol is to be useful, extensive training will be

needed for the intended audience and the symbol must not be used to convey

information about potential hazards to the general public or to any non-trained

audience.

Similar remarks apply to laser, which did not communicate successfully on its

own. In fact both the laser and biohazard symbols communicated the idea of

radiation to about 10 percent of those tested. Training and supplementary word

signs are needed for each of these three messages if these symbols are used.

Along with image A for overhead hazard, image B for entanglement and the two

images for general warning, these three images are among the most abstract

studied in the present experiment. None of the seven abstract images tested

were very successful at communicating their intended message, and clearly

require training and auxiliary signage to communicate successfully. Informal

exposure such as the lengthy use of the radiation symbol is not sufficient

judging by the relatively poor performance of this particular symbol. In any

situation, where one of these symbols might appear on a consumer product or public space, auxiliary hazard information must be provided to ensure the

safety of the user.

55
Radiation ABCLaser Biohazard

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88 N = 86

C 58.5% 1.1% 0 % C+P 65.9 25.0 1.2 X 34.0 38.7 46.5

N 0 36.4 52.3

Naive N = 53 N = 54 N = 61

C 30.2% 5.6% 3.3%

C+P 30.2 25.9 3.3 X 56.6 61.1 72.1

N 13.2 7.4 24.6

Wrong caution fans, blades radiation area radiation

Answers ventilation system, fan caution sunshine blades, rotating

moving parts, shaft explosion, explosive object

hearing protection, caution, welding flying, falling

noisy area high voltage, wires objects

siren solar energy plant sharp cutting objects snow area moving machinery parts

flying debris heavy machinery

no light allowed space craft

multiple outlets

emergency area, vehicles

intersection

Confusions *fall out shelter 3%

56
Consideration of the data on hazard symbols summarized in figures 1 through 12

suggests that symbols which include both the hazard and a person will be the

most likely to be correctly defined. Furthermore, participants generally

preferred this style of representation and stated that it is most effective.

The only exception was a symbol for overhead hazard in which the image of a crane load without a human figure was preferred.

Although some preference for yellow and the triangle as background shape was expressed, these features did not appear to affect understandability in any

substantial way. In four cases, flammable, corrosion, slip, and forklift,

the symbol with the highest percentage of correct plus partial answers was shown as yellow with the triangular surround shape. In five cases, however,

explosion, electricity, entanglement, fall, and overhead hazard, the "best"

symbol was presented as black and white in a square surround. Participants

appear to have responded primarily to the image content rather than the surround

and color. They did, however, indicate in comments in the preference section,

an awareness of the common practice of the use of a triangle to indicate

hazard, yellow to indicate caution, and red to indicate danger. Of course,

features such as surround shape and color were not systematically varied or studied in the present study. Any deductions about their effectiveness remain

purely inferences.

In five cases, explosion, corrosion, poison, fork-lift, and general warning,

the ISO/EEC proposed image was the best understood. Images for other ISO

referents which did more poorly included electricity, flammable, overhead

hazard, laser, and radiation. Entanglement, slip, fall, and biohazard are not

included in current ISO recommendations. The ISO images may tend to be somewhat more familiar in that many of these are used on the DoT/UN hazard materials transport placards. Yet, it is interesting to note that the images for

electricity and flammable hazards did not perform particularly well despite

their widespread use. These data reinforce the need to determine the understandability of hazard warning images before standardization or widespread

use.

Referents for which no image reached an 85 percent criterion level of

performance for either strict or lenient scoring categories included radiation,

laser, biohazard, flammable, poison and general warning. Flammable and poison

were the best understood of these, performing at about the 75 percent level.

For all other hazard referents, at least one image met the ISO criteria of

85 percent correct response and fewer than five percent critical confusions.

In general, symbols in the other referent categories received a higher

percentage of correct answers than did the hazard warning symbols. Although

each category will be discussed in detail, the protective gear and safety

message images were quite well understood. Only the egress-related messages

caused understandability problems as serious as some of the hazard warning

messages

.

57
Figure 13. No open flame

A B C

UNDERSTANDABILITY DATA

Informed N = 86 N = 88 N = 94

C 68.6% 73.9% 71.3%

C+P 90.7 95.5 95.8

X 5.8 3.4 3.2

N 3.5 1.1 1.1

X2 X

2 =2 . 73 , df =4 , NS

Naive N = 61 N = 54 N = 53

C 70.5% 87.0% 71.7%

C+P 93.5 98.1 96.2

X 6.6 1.8 3.8

N 0.0 0.0 0.0

Critical *fire, open flames 4.7% *watch out for fires 1.1% *fire 2.1%

Confusions *no fire hazard 1.2%

PREFERENCE DATA

Industrial 42.6% 45.7% 8.6%

X2 X2 =58.39, df=2 , p<.001

Naive 50.6% 45.5% 3.8%

Reasons no reason no reason no reason

excludes all flames more graphic, visible easiest to understand

clearer, easier to see shows no open flame better match clearer

& understand shows matches, beware

depicts flame better easiest to understand

58
5.2.3 Prohibited Action Messages

The category of prohibited actions, including no smoking and no open flame

contains images that generally were defined correctly. For "no open flame,"

figure 13 reveals that for lenient scoring all images tested above 90 percent

correct. Image A created some problems with 5.9 percent of the industrial

personnel responding that it meant fire, open flames, or no fire hazard, each a critical confusion. Both images B and C received only one to two percent critical confusions. Data for industrial and naive participants were similar

although the naive people performed slightly better.

Generally, industrial participants preferred version B, while naive participants

preferred image A. Image A was preferred because it excluded all flames,

while image B was believed to be more graphic or visible. Image B, because of

the lack of critical confusions, good understandability data, and industrial

preference would appear to be a good representation of "no open flame," at

least for industrial applications. Image C was selected by very few people.

Figure 14 presents data for "no smoking" for which both images did equally well,

for both participant groups with no critical confusions. Image B was selected

as the most appropriate image by a significant majority of those tested. Its

clarity, contrast, and good graphics were among the major reasons for this

choice

.

The use of the circle and slash now appears to be a meaningful way of indicating

prohibition. When Brainard et al. (1961) conducted their research two decades

ago, this symbolic convention was not well understood in the U.S. Data from

the present experiment, and from one by Lerner and Collins (1980) indicate that

subsequent public exposure has been sufficient to "teach" the meaning of the

circle and slash reasonably well.

5.2.4 Safety and Fire Emergency Messages

The safety messages tested included first aid, safety shower, and eyewash.

Both images for first aid (fig. 15) were well understood, above the 85 percent

criterion for lenient scoring, with no significant difference in understandability between the two. Wrong answers for image A included safety, cross

roads, and red cross, while wrong answers for image B included "watch fingers"

and hand safety. Image A was chosen significantly more frequently as appropriate by industrial personnel because of its existing standardization and link

to the idea of medical assistance. Image B which includes the cross, represented the idea of completed first aid to a minor injury. Naive participants

saw little difference between images A and B. Because of good understandability

and general industrial preference, image A, the cross, appears to be a good

candidate symbol for first aid.

Figure 16 presents data for safety shower, for which only one image, B, performs

above criterion for leniently scored data (although image C is close). In all

cases, the difference between strict and lenient scoring is due to failure to

specify "safety shower." Participants were aware that the image related to

59
Figure 14. No smoking

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86

C 96.8% 96.5%

C+P 97.9 96.5

X 1.1 2.3

N 1.1 1.1

X

2 Z=0.20, df =1 , NS

Naive N = 53 N = 61

C 96.2% 96.7%

C+P 98.1 98.4

X 1.9 1.6 N 0.0 0.0

Wrong

Answers

PREFERENCE DATA

Industrial 35.1% 55.4%

X2 Z = 3.17, pC.Ol

Naive 28.2% 71.8%

Reasons no reason no reason

better graphics stands out, more visible

cigarette more looks more like cigarette

realistic black on white background

60
Figure 15. First aid

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86

C 82.9 88.4

C+P 87.1 91.9

X 11.7 8.1

N 1.1 0

X

2 Z=0 .67 , df=l , NS

Naive N = 53 N = 61

C 90.6 86.9

C+P 94.4 93.5

X 5.7 6.6

N 0.0 0.0

Wrong safety watch fingers, danger

Answers crossroads, intersection

white, red cross hand safety

PREFERENCE DATA

Industrial 59.0% 39.6%

X2 Z = 2.91, p<.01

Naive 46.8 53.2

Reasons no reason no reason

standard sign shows completed first aid

medical assistance shows minor, hand injury

red cross best, better understood

61
Figure 16. Safety shower location

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86 N = 88

C 47.9% 60.5% 46.6%

C+P 76.6 98.9 84.1 X 20.2 1.2 9.1 N 3.2 0 6.8

X2 X2=200, df =4 , pC.OOl

Naive N = 53 N = 61 N = 54

C 26 .4% 60.9% 31.5%

C+P 66.0 99.9 85.2

X 30.2 0.0 14.8

N 3.8 0.0 0.0

Wrong sprinkler system control sunlamp, bright lights

Answers falling water, wet area watch for falling objects

shower room, bathroom

PREFERENCE DATA

Industrial 1.4% 83.8% 14.9%

X2 x2=260.35, df=2 , p<.001

Naive 1.3% 75.6% 23.81%

Reasons no reason no reason no reason

good but lacks person more information, detail clearer, more clarity person using shower understandable

clear, most understandable graphic, more visible

shower clear good contrast

relates better to safety

62
water or shower; they did not always express its relation to safety. Only

image C elicited responses unrelated to water, such as lights or falling

objects. Image B was preferred by both groups because it provided the most

information, showed actual use, had a person fully clothed, and generally was clearer and related better to safety. This symbol could suffer, however, from

very poor legibility due to its extreme complexity.

Figure 17 presents data on three images for eyewash location. This referent is one of the few for which no significant difference between images occurred for

either the understandability or preference data. The percentage of correct

responses for each image was about 65 percent regardless of scoring criterion

while the percentage of industrial personnel choosing each image was about 31

percent. The percentage of correct responses was lower for all images for

naive participants, who are less likely to have been exposed to an industrial

eyewash. These people also expressed a preference for image C. Lack of

familiarity with an eyewash may account for the large number of wrong answers associated with eye irritant, hazardous material splashing, and eye protection

needed. Only image A, the most directly representational image, did not elicit

a large number of these opposite confusions. The preference data indicate that

image A was preferred because it shows the eye and water and was clearer, while

image C was selected because the eye and fountain were clearer and the eye was more realistic. Nevertheless, none of these images was particularly successful

in conveying the message of eyewash.

Of the symbols for safety related referents, only those for eyewash did not

reach criterion level, perhaps due to lack of familiarity with this equipment

(which is needed only where chemical irritants are used.) Use of the color

"green" for all of these images elicited no comments nor did the use of a square background shape. Two people did comment that the cross should be

red—for red cross. The one abstract safety image, a cross, was well understood, probably because of its widespread use for centuries to represent aid

or help.

Figures 18 and 19 present data for fire emergency referents, including

extinguisher, hose and reel connection, and fire alarm call point. Both fire

extinguisher and hose and reel, figure 18, were correctly defined above the

85 percent criterion level. Performance on these two symbols for lenient

scoring criteria was very similar to that reported by Lerner and Collins (1980).

Since only a single symbol was tested, no preference data were obtained for

either of these two messages. Fire alarm call point, figure 19, created a number of problems, due to confusion about the intended message. It was intended to mean "fire alarm call point," or the location where an alarm is

turned in. Many people, however, treated it as "fire alarm" or the location

of an alarm sounder to warn building inhabitants of a possible fire. As a result, answers referring only to "fire alarm", or "fire phone" were identified

separately and amounted to 17 percent of the answers for image A, 50 percent of

the answers for image B, and 90 percent of the answers for image C. Inspection

of figure 19 reveals that most participants did not respond with ideas of "fire

alarm call point", (as the data were scored for industrial personnel) for any

of the images. Furthermore, images A and B elicited a large number of answers

related to noise, ear protection, school, church, wheels, and rotating shafts.

63
Figure 17. Eyewash location

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88 N = 86

C 64.9% 63.6% 62.8%

C+P 67.0 64.7 64.0

X 19.1 23.9 32.6

N 13.8 11.4 3.5

X

2 X2 =0.08, df=2 , NS

Naive N = 53 N = 54 N = 61

C 34.0% 40.7% 49.2%

C+P 56.6 46.3 55.8 X 44.4 46.3 45.3

N 0.0 7.4 0.0

Wrong water fountain splashing 14% Answers eyes & nose running someone watching you

overhead hazard area weighing scales

Confusions watch for eyes & mouth 2% eye irritation, danger 12.5% eye protection should be wear eye protection 12.5% worn 18.6%

eye hazard, material

splashing 14%

PREFERENCE DATA

Industrial 31.3% 32.4% 30.9%

X2 X2 =0.09, df=2 , NS

Naive 17.9% 27.6% 46.8%

Reasons no reason no reason no reason

shows basin, real shows eye & water clearer, more equipment clearer, more descriptive understandable

shows person washing eye better symbol eye & fountain clearest

best, self explanatory better eye

64
Figure 18. Fire safety equipment

Fire Extinguisher

A Hose and Reel Connection

B

UNDERSTANDABILITY DATA

Industrial

C 96.5% 88.6%

C+P 98.8 95.4

X 1.2 1.1 N 0 3.4

Naive N = 61 N = 54

C 95.1% 87.0%

C+P 96.7 92.6

X 3.3 5.6

N 0.0 1.8

Wrong fire hazard area high pressure

Answers

gas available here

Confusions *fire oxygen

65
Figure 19. Fire alarm call point

A B C

UNDERSTANDABILITY DATA

Industrial N = 88 N = 86 N = 94

C C+P

X

N

2.3%

10.2

59.1

13.6

fire alarm = 17%

2.3%

4.6

37.2

8.1 fire alarm = 50%

1.0%

6.3

1.1

0 fire alarm =2.1%

fire phone = 90.4%

X2 X2=100.59, df=2, p<.001

Naive N = 54 N = 61 N = 53

C C+P

XN

37.0%

48.1

48.1

0.0

fire alarm = 3.7%

37.7%

42.6

39.3

6.6

fire alarm = 11.5%

79.2%

79.2

9.4

0.0

fire alarm = 11.3%

Wrong Answers

noise area, hearing

protection

bells ringing

school zone church

signal, siren

high noise, use ear protection

bell

grinding wheel

machine, rotating shaft

fire caution

vibration upon striking

PREFERENCE DATA

Industrial 12.6% 46.8% 34.2%

X2 X2 =42 . 62 , df=2, pC.001

Naive 15.4% 43.6% 35.9%

Reasons no reason

shows bell more understandable as an alarm

no reason

better, more easily

recognized

hammer & bell

no reason

shows fire & phone

indicates alarm location

66
Image B was selected as the most preferred image because it was more understandable as an alarm and could be more easily recognized. Reasons for

selecting image C included that it showed a fire and phone as well as an alarm

location while reasons for image A included that it showed a bell. Nevertheless, the message of fire alarm call point appears to be difficult to isolate

symbolically from that of fire alarm sounder location.

5.2.5 Personal Protective Gear

The next category of symbolic referents to be considered is that of personal

protective gear, figures 20 to 25. With the exception of images for respirator,

almost every image tested well above the 85 percent criterion level. Four

different graphic approaches were employed for the various referents: one piece of gear, two pieces of gear, gear on person, and putting gear on. Understandability was often greater for gear on person, although individual comparisons were generally not statistically significant. The preference data tended

to favor the putting gear on approach, particularly for the naive participants.

Despite the preference for this approach, it does not appear to be necessary to

convey the message of "wear protective gear" since most symbols for protective

gear tested above the 85 percent criterion. The simpler symbols, which can be

more legible, appear to be sufficient to communicate the intended message.

Figure 20 presents data for "wear hard hat." There is a significant difference

among the images with A, "putting on hard hat," performing most poorly. Confusions included ideas of hair protection, wear respirator, cover ears, hold

onto hat, etc. Image C, hard hat alone, had the highest percentage of correct

answers for both naive and industrial participants, and was significantly preferred by the latter group. (Naive people preferred image A, however.) Image C was selected because the image alone was considered sufficient, image B was chosen because it showed the hat on a person, and image A was preferred because

it showed a person putting on a hat.

Figure 21 presents data for ear protection. Image C, ear protection on a person, received the highest percentage correct, but the difference in percentage correct between the three images was not significant. Image B, ear protection alone, tested below criterion level for industrial personnel. Industrial

participants did better on all three images than naive because of the latter's

tendency to define the images as (stereo) head sets rather than as protective

gear. Again, familiarity with the industrial workplace tended to increase the

understandability of this particular message. Answers related to noise hazard

and head phones were identified separately for the industrial subjects although

they are also included within the lenient category.

Both groups of participants expressed a strong and significant preference for

image A, because it showed the gear being put on and had a greater detail.

Images B and C were liked because they were simpler, clearer, and more visible.

Image B of figure 31, presents data for a fourth graphic image which was not

particularly effective for "hearing protection" but which was generally

responded to as "noise hazard" or "noise hazard, wear ear protection." If the

intention is to transmit information about a potential hazard, rather than the

specific requirement for protective gear, this image appears to be a viable

67
Figure 20 Head protection required

A B C

UNDERSTANDABILITY DATA

Industrial N = 86 N = 88 N = 94

C 84.8% 86.4% 88.3%

C+P 87.1 95.5 97.9

X 9.3 1.1 1.1 N 3.5 3.4 1.1

X2 X

2 =12 .84 , df=4, p<.05

Naive N = 61 N = 54 N = 53

C 80.3% 77.8% 96.2%

C+P 90.2 90.8 98.0

X 6.6 7.4 1.9 N 3.3 1.8 0.0

Wrong wear hair protection

Answers

PREFERENCE DATA

Industrial 29.5% 23.4% 46.6%

X

2 X

2 -19.36, df=2 , p<.001

Naive 52.6% 19.2% 25.6%

Reasons no reason no reason no reason

shows putting hat on shows hat on person hat alone is sufficient

more graphic clearest, most visible

best, most understandable most recognizable, best

68
Figure 21. Ear protection required

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88 N = 86

C 79.8% 79.5% 79.1 % C+P 86.2 81.8 90.7

X 2.1 6.8 3.5 N 4.2 3.4 0

X

2 X

2 =4.63, df=4, NS

Naive N = 53 N = 54 N = 61

C 45.3% 48.1% 45.9%

C+P 56.6 59.2 60.7 X 8.2 9.2 8.2 N 4.9 0.0 4.9

headphones 26.2% headphones 31.5% headphones 26.2%

Wrong head phones 2.1% tunnel hearing test Answers noise hazard 5.3% noise hazard 7.9% noise hazard 4.7%

head phones 1.2%

PREFERENCE DATA

Industrial 65.8 17.1 16.7

X2 X2 =106. 54, df=2 , p<.001

Naive 62.8 12.8 6.4

Reasons no reason no reason no reason

shows gear being put on simple, most visible simpler, clearer

more detail

clearer, easier to understand

69
Figure 22. Eye protection required

A B C

UNDERSTANDABILITY DATA

Industrial N = 88 N = 86 N = 94

C 81.8% 88.4% 84.0%

C+P 89.7 100 98.9

X 0 0 0 N 2.2 0 1.1 glasses alone 7.97%

X2 X2 =l . 50, df=2, NS

Naive N = 54 N = 61 N = 53

C 63.0% 78.7% 94.3%

C+P 87.1 91.8 98.1

X 12.9 8.2 1.9

N 0.0 0.0 0.0

Wrong none Answers

PREFERENCE DATA

Industrial 10.6% 38.3% 50.7%

X2 X2 =56.38, df=2, p<.001

Naive 6.4 33.3 60.2

Reasons no reason no reason no reason

clearest, simplest person wearing goggles imply eye glasses protection

most meaningful looks more like safety

equipment

clearer, more understandable

70
option (especially since 36 percent of the industrial personnel responded

with "ear protection required" anyway).

Figure 22 presents data for eye protection. Using lenient scoring criteria,

all images tested above criterion level with no significant difference between

images emerging, although image A, glasses alone, had the lowest percentage of

correct responses. This was due to some participants merely indicating "wear

glasses", not "wear safety glasses”. Image C, goggles, was preferred because

it appeared to indicate a greater level of protection. Image B was preferred

because it showed the intended action, and had greater meaning, while A was believed to be clearest. Although all the images were tested as general eye

protection equipment, the good performance of image C for all participants indicates that if a separate image is needed for goggles, as opposed to glasses,

this image could effectively serve that need. Image B appears effective for

the general protection, since it elicited no wrong answers at all from

industrial personnel.

Figure 23 presents data for hand protection. No significant understandability

differences among images emerge, although image B elicits a number of confusions

related to "stop", particularly from naive participants. All images except

image B exceeded the criterion level with lenient scoring for all people.

Image A, "putting on gloves", was preferred by both sets of participants because

it showed this action. Reasons for selecting image B include that it was simpler and for image C that it shows two hands.

Figure 24 presents data for foot protection. There is a significant difference

between images, with image A having the highest percentage correct and image C

the lowest for industrial personnel. Differences between lenient and strict

scoring criteria are attributable to failure to indicate that safety shoes or boots are required. Image C also elicited a large number of answers (12 percent) related to wearing rubber boots rather than to safety footgear. Nevertheless, image C was preferred because it showed the boot being put on the

person. Reasons for preferring image A included that it showed the hard toe,

and for image B, that it was simpler.

Figure 25 presents data for three images for respirator required. Differences

in scoring criteria are responsible for the variations in percentages correct

and partially correct. Only about half the participants strictly identified

any image as meaning "respirator required". If ideas such as noxious fumes and

face or breathing protection are considered partially correct, this increases

leniently scored performance for all three images. If “gas mask required" is

also included, this further increases the percentage of correct definitions for

images A and C for both groups to 90 percent or better. The words "gas mask"

may refer to the kind of equipment issued during World War I to supply air

during a gas attack, rather than the modern day respirator; hence this answer

is categorized separately for industrial participants. If this answer is scored

as leniently correct, then the performance of symbols A and C exceeded the criterion level and was significantly different from image B. Image B was not well

understood by any scoring criterion and elicits numerous confusions related to

scuba gear and electronic equipment. Participants expressed a significant preference for image A, although this preference was somewhat less marked for naive

71
UNDERSTANDABILITY DATA

Industrial N = 94 N = 86 N = 88

C 86.2% 84.9% 82.9%

C+P 96.8 90.7 90.8

X 3.2 5.8 5.7

N 0 3.5 3.4

X

2 X

2 =4.42, df=4 , NS

Naive N = 53 N = 61 N = 54

C 90.6% 60.7% 87.0%

C+P 100 64.0 100 X 0 31.2 0 N 0 3.3 0

Wrong stop wash your hands Answers direction follow watch fingers, handle

left turn with care

PREFERENCE DATA

Industrial 65.8% 17.1% 16.7%

X2 X2=228.19, df=2 , p<.001

Naive 89.7% 5.1% 5.1%

Reasons no reason no reason no reason

shows action simpler, clearer shows two hands

better, clearer, easier

to understand

72
Figure 24. Foot protection required

A B C

UNDERSTANDABILITY DATA

Industrial N = 88 N = 94 N = 86

C 82.9% 70.2% 57.0%

C+P 96.5 95.7 84.9 X 1.1 4.2 13.9

N 2.3 0 1.2

X2 x2=18.76, df =4 , p<.001

Naive N = 54 N = 53 N = 61

C 53.7% 62.3% 50.8%

C+P 79.6 90.6 90.2

X 16.7 9.4 8.2

N 3.7 0.0 1.6

Critical *leave shoes here rubber boots needed 12.8%

Confusion

PREFERENCE DATA

Industrial 14.4% 22 . 5% 60.8%

X2 X2=83.68, df=2 , p<.001

Naive 1.3 14.1 84.6

Reasons no reason no reason no reason

shows hard toe , looks simpler, easier to action of putting on boot

like safety shoes read most meaningful

easiest to understand boot & person

73
Figure 25. Respj.^ .tory protection required

UNDERSTANDABILITY DATA

Industrial

C C+P

X

N

N = 88

51.1%

73.2

2.3

2.3

gas mask = 21.6%

N = 86

51.2%

67.5

8.1

18.6 gas mask = 5.8%

N = 94

44.7%

66.0

1.1 3.2 gas mask = 24.5%

X2 X

2 =0. 37 , df=2, NS

Naive

C C+P

X

N

N = 54

83.3%

92.5

1.8 0.0

gas mask = 5.6%

N = 61

50.8%

60.6

24.6

11.5 gas mask = 3.3%

N = 53

77.4%

94.4

0.0

0.0

gas mask = 5.6%

Wrong

Answers

scuba gear, diving

electronic gear,

robots

PREFERENCE DATA

Industrial 61.9% 9.2% 27.5%

X2 X

2 =96.72 , df=2, pC.OOl

Naive 50.0% 16.7% 26.9%

Reasons no reason

detail of mask

person & mask

clearer, easier to understand

best

looks more like

respirator

no reason

no reason

good mask

more easily understood

74
subjects. Image A is a more realistic representation of a person wearing a mask than the more stylized image C. Unfortunately, the respirator shown in

image A is out of date and should be modernized. It was preferred, however,

because it showed the most detail and was shown on a person. Image B was believed to look like a respirator while image C was believed to be a good

representation of a mask. Image A of figure 31 presents data for an ISO proposed symbol for dust mask, similar to but distinct from the idea of respirator.

When leniently scored as dust mask, this image came close to the 85 percent

criterion level, with no critical confusions. Naive participants appeared to

have even fewer problems with this image, perhaps because it resembles dust

masks commonly sold for home use.

As noted earlier, at least one image for all the personal protective gear

referents was understood at or above the criterion level, if a lenient scoring

criterion is adopted. Distinguishing between images on the basis of the understandability data is almost impossible, and on this ground alone, it appears

that almost any image could be selected. However, because of the legibility

problems inherent in the greater detail associated with the "putting on gear"

approach, and because the gear alone approach is typically the least well

understood, if a consistent set of images is desired, portrayal of gear on a person appears to be an effective general approach. Symbols using this approach

had slightly higher percentages correct for four of the six referents studied.

The use of color and background shape for protective gear symbols was only

infrequently addressed by any of the participants in the preference portion.

Only two images , goggles and breathing apparatus , were presented in yellow;

all other images were blue, and presented in a circular surround. Five people

commented that these latter images should have been presented on a yellow

triangle. For goggles, however, ten percent of those prefering this image

preferred it because it was in the colors of hazard or caution signs. No

participant, however, commented upon the use of blue or the round surround

shape. It does appear, however, that some industrial personnel recognize the

international coding system which uses the triangle to indicate the presence

of a hazard and yellow to indicate caution.

5.2.6 Egress-related Referents

The next category to be considered is that of egress related referents. Three

images each were studied in the main experiment for emergency exit (figure 26)

and general exit (figure 27). Lerner and Collins (1980) and Collins and

Pierman (1979) called attention to the need to develop an effective emergency

exit symbol, as well as to the generally poor performance of currently proposed

exit symbols. Data obtained in the present experiment for emergency exit for

symbols B and C of Figure 26 generally replicate those of Lerner and Collins.

Symbols A and C are correctly identified by most industrial personnel. Industrial participants, however, did more poorly on symbol B (strict criterion) in

the present experiment, with a large number of responses related to "do not

run". Symbols A and B also received several critical confusions related to

"enter" and "do not open door during fire". Only symbol A performed above the

criterion level for lenient scoring for both groups of participants. Emergency

75
Figure 26. Emergency exit

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88 N = 86

C 90.4% 64.8% 90.7%

C+P 95.7 72.7 93.0

X 4.2 21.6 4.7

N 0 5.7 2.3

X2 X

2 =26.75, df=4, p<.001

Naive N = 53 N = 54 N = 61

C 83.0% 68.5% 82.0%

C+P 88.7 83.3 82.0

X 11.3 14.8 18.0 N 0.0 0.0 0.0

passageway 1.8

Wrong fire, run beware, fire do not run 18% fire hazard area Answers run, keep away from fire

Critical *do not open door if *enter 1% Conclusions fire 1%

PREFERENCE DATA

Industrial 53.2% 21.6% 23.9%

X2 X2 =42 . 62 , df=2 , p<.001

Naive 51.3% 19.2% 19.2%

Reasons no reason no reason no reason better characterized green shows go shows emergency & red implies emergency safety direction

shows both emergency & others restricted to egress fire exit more meaningful

76
exit is a concept intended for general public use; these data suggest that

such a message which is initially understandable (without training) continues

to be difficult to symbolize.

Participants expressed a general preference for symbol A claiming that it was better characterized, the color red implied emergency, it showed both emergency

and egress, and was more meaningful. Image B was selected because green indicated both go and safety and the other symbols appeared to be restricted to

fire exit. Image C was chosen because it showed both emergency and direction.

Image C of figure 31 presents an additional emergency exit symbol showing a man running plus a door and an arrow. The percentage of correct responses to

this image is lower by 20 to 25 percent than to the same image with a figure

walking (image C of figure 27) due to numerous answers related to "do not

run" (13.5 percent) and men's room (5.8 percent). These confusions were not

elicited by the image with the man walking to the door. It is interesting to

note that a relatively simple shift in figure rendition decreased the number

of correct answers noticeably.

Figure 27 presents data for general exit. Only image C reached the 85 percent

criterion level for lenient scoring for both groups. Image B, proposed by DoT,

(AIGA, 1979) received a very small percentage of correct answers regardless of

scoring criterion or participant group studied. Image A received only 40 to 60

percent of correct answers for industrial personnel. Furthermore, all images,

particularly image B, received a large number of opposite responses. For image

A, two percent of those tested responded with "enter" (as opposed to "exit"),

for image B, twelve percent of those tested responded with "do not exit, enter"

and "do not cross or start", while for image C, one percent responded with

"dead end." Image B appears to be singularly unsuccessful in that it was not

understood and elicited a large number of opposite responses.

Participants expressed an overwhelming preference for image C because it showed

figure, direction, and door, and was less confusing than the others. Image C

is the least abstract of the images tested and the most frequently correctly

identified. It may not, however, be an effective exit message when located

directly over a door, as are current "EXIT" signs (AIGA, 1979). No reasons

were given for preferring B, while A was preferred because the arrow pointed to

the opening.

Consideration of the various images proposed for exit and emergency exit

suggest that those showing a figure, flames, door or an arrow received the

greatest percentage of correct answers. The images that were successful in

terms of percentage correct are all complicated visually, involving several

graphic elements. Yet these complicated images may be less likely to be detect

able or legible in smoke. Selection of a successful exit symbol is contingent

upon satisfying both comprehension and legibility criteria. It does not appear

than an image which satisfies both needs has yet been located and evaluated.

Furthermore, the criterion for successful comprehension should perhaps be set

higher than 85 percent correct definition due to the criticality of the message

77
Figure 27. Exit

A B c

UNDERSTANDABILITY DATA

Industrial N = 88 N = 86 N = 94

C 39.8% 2.3% 82.9%

C+P 59 .1 26.7 90.3

X 37.5 39.5 3.2

N 3.4 33.7 3.2

passageway = 3.2%

X

2 X2 =160.69, df=4, p<.001

Naive N = 54 N = 61 N = 53

C 68.5% 1.6% 79.2%

C+P 83.3 6.6% 86.7

X 13.0 81.5% 5.7

N 3.7 24.1% 1.9 passageway = 3.7% passageway = 5.7%

Wrong one way only roadway, highway

Answers narrow passageway divided building,

aisle, walkway, thruway decision

civil defense, safe

shelter

proceed, cross with

caution

go straight

Critical *enter 2% *don’t exit, enter 8.1%

Confusion *don't cross, pass,

1 start 4.6% *dead end 1.1%

PREFERENCE DATA

Industrial 12.8% 2.3% 78.2%

X2 X2=241.4, df=2, p<.001

Naive 9.0% 1.3% 80.8%

Reasons no reason no reason no reason arrow points to opening figure & direction

shows door & way out better, others confusing

more meaningful

all bad

78
Figure 28. No exit

A B C

UNDERSTANDABILITY DATA

Industrial N = 94 N = 86 N = 88

C 13.8% 27.9% 34.1%

C+P 18.0 38.4 59.1 X 45.7 31.4 1.1 N 14.9 3.5 2.3 no entry 21.3% no entry 26.7% no entry 37.5%

X2 X2 =35.87, df=4 , p<.001

Naive N = 53 N = 61 N = 54

C 11.3% 37.7% 26.6%

C+P 17.0 39.3 35.2 X 83.0 41.0 55.6 N 0.0 0.0 1.8 no entry 19.7% no entry 7.4%

Wrong fire door no running

Answers shut, close door slippery, tripping

prison, jail hazard

secure, protected area no loafing, standing

danger crossing, do not

cross Critical *keep door/area locked *exit, exit slowly,

Confusion 14.9% open doorway - 3.4%

*emergency exit 2% *entrance 2%

PREFERENCE DATA

Industrial 4.3% 30.0% 64.9%

X

2 X2=124.3, df =2 , p<.001

Naive 1.3% 39.7% 57.7%

Reasons door locked, no way out no reason no reason

no reason universal slash for no X for no more meaningful, stands more meaningful

out more figure passing by door

similar to highway "no better, door best

entry" simpler, less cluttered
Figures 28 and 29 deal with symbols for no exit and no entrance, respectively.

When Collins and Pierraan (1979) and Lerner and Collins (1980) examined several

symbols proposed for "no exit", they found that no symbol tested was effective

and several had serious critical confusions. In the present experiment, figure

28 reveals that again, no image regardless of scoring criterion or participant

group, received a high percentage of correct answers. Furthermore, all of the

images received as large a percentage of incorrect answers related to "no entry"

as they did fully correct answers for "no exit", indicating that the message of

"no way out" was not successfully communicated. Images A and B also received

between two and three percent responses related to exit or entrance, a critical

confusion. Furthermore, 15 percent of the answers to image A indicated that it

meant to keep door locked. Image C was correctly identified by the largest

percentage of subjects but fell short of the 85 percent criterion level. It

was, however, the most frequently chosen image in the preference data because

of the prohibitory "X", the figure passing by the door, and its simplicity.

Image B was selected because of the prohibitory slash and because it appeared

more meaningful. Image A was selected because it showed the door being locked.

These data reinforce the difficulty seen in previously reported data (Lerner

and Collins 1980; Collins and Pierman, 1979) of determining a symbolic image

which successfully communicates the message of "no exit" or "no way out".

Figure 29 presents data for three images specifically intended for "no entry"

or " no admittance". Despite extensive use on the highways, image A is not

understood to mean "no entry", at least for an industrial setting. In fact,

responses from naive participants indicated a greater comprehension of this

image, although fewer than half of these participants interpreted it correctly.

Furthermore, image A elicited answers related to hallway or passageway from

almost six percent of those tested. As ISO TC 145 has recently recommended

(Zwaga, 1981), this symbol might best be restricted to vehicular "no entry".

Although image B does not communicate the strict message of "no entry” well at

all, it does communicate the idea of "stop” to 72 percent of those tested

(industrial or naive). Image C indicates "no entry" to about 75 percent of

those tested and "no standing" to another 12 percent. Image C was also the

most preferred image by industrial personnel, as it indicated people not allowed

and possessed the prohibition slash. Image B was preferred because it was easier to identify with and contained a hand signal. Image A was recognized

as a common symbol, even if it was not correctly identified.

Data presented in figures 26-29 for egress-related referents indicate that

these ideas continue to be difficult to symbolize effectively. Egress symbols

which may be most legible may not be well understood and vice versa, while

ideas related to prohibited exit and entry are not well understood regardless

of legibility. The poor performance of symbol A for no entry (an abstract

symbol) suggests that it does not appear to have achieved universal comprehension despite widespread use on highways.

A final egress related referent, "use stairs, not elevator in fire" is presented in figure 30. Images A and B both received at least 85 percent correct

responses for all participants for lenient scoring. Differences between strict

and lenient scoring were due to answers related to fire exit, fire escape or fire stairs which did not include both the message "use stairs" and "do not

80
Figure 29. No entry

ABC

UNDERSTANDABILITY DATA

Industrial N = 88 N = 86 N = 94

C 20.4% 13.8% 74.4%

C+P 30.6 85.0 76.7 X 30.7 12.8 7.9

N 38.6 2.1 4.7

no standing 11.6%

X2 X2 =178.69, df=4, pC.OOl

Naive N = 54 N = 53 N = 61

C 35.2% 24.5% 63.9%

C+P 48.2 92.4 78.7 X 42.6 7.5 19.7 N 9.2 0.0 1.6

Wrong bright light, red light quiet, no noise do not cross Answers beware, caution, danger wear hand & ear no running, loitering

low ceiling protection

red dot slow down

Critical *hallway, passageway *safety walkway 1% Confusions 5.7%

no way out , dead end 2%

PREFERENCE DATA

Industrial 8.3% 38.3% 47.1%

X2 X2 =58.65, df=2, p<.001

Naive 11.5% 38.5% 33.3%

Reasons common symbol no reason no reason

no reason easier to identify with indicates people not better, more allowed

understandable more understandable

hand signal like traffic sign

slash for no

81
Figure 30. Use stairs in case of fire, not elevator

A B

UNDERSTANDABILITY DATA

Industrial N = 94 N = 88

C 22.3% 62.5%

C+P 90.4 86.4

X 8.51 12.5

N 1.06 1.14

X2 Z=32.24, df=2 , p<.001

Naive N = 53 N = 54

C 75.5 81.5

C+P 88.7 90.7

X 11.3 7.4 N 0.0 1.9

Wrong get out, leave fire exit, blocked

Answers watch out for fires, danger

do not run down stairway

in fire

do not enter

PREFERENCE DATA

Industrial 21.2% 77.0%

X2 Z = 8.40, p<.001

Naive 7.7% 87.2%

Reasons no reason no reason

more understandable indicates don't use elevator

clearer, easier to spot at more meaningful

a glance shows both meanings

better

82
Figure 31

UNDERSTANDABILITY DATA

Industrial N = 86 N = 84 N = 52

C 67.4 36.2 61.5

C+P 84.8% 90.3 67.3 X 15.1 8.5 23.1 N 12.8 2.1 9.6

Naive N = 53 N = 53 N = 54

C 78.7 9.4 68.5

C+P 96.8 94.3 92.6 X 0.0 5.7 3.7 N 0.0 0.0 3.7 gas mask 5.79

Wrong sand blasting area listen do not run Answers painting or spraying audio alarm, bell ring restrooms

sound, radio waves *no exit, obstacle in

way 3.8%

Critical

Confusions

83
use elevator". Image A does not, in fact, contain any imagery related to the

elevator concept—-hence the large difference between strict and lenient scoring

for industrial personnel. (Answers generally related to exit were typically

scored as correct in the pilot but were only scored as partially correct in

the main experiment). Participants expressed a strong preference for image B

because it depicted both meanings, including the elevator. Again, image B may

suffer greater legibility problems under smoke or dusty conditions. This

referent, furthermore, appears less critical for industrial sites where egress

is normally by stairs.

Data contained in figure 31 have already been discussed under the individual

referents of respirator, ear protection, and emergency exit.

84
6. CONCLUSIONS

6 . 1 SELECTION OF A PRELIMINARY SYMBOL SET BASED UPON UNDERSTANDABILITY DATA

The data on symbol understandability obtained in the present experiment were

used to select a preliminary set of symbol images which appear to convey the

various referents effectively. The selection is based upon a set of arbitrary

decision rules, given below. Before describing these rules, however, certain

intrinsic limitations to the generalizability of these conclusions must be

addressed

.

Throughout the present report, understandability has been emphasized as a major

consideration in symbol evaluation. While the understandability of a set of

symbols should be a primary consideration, there are other important factors

which should also be addressed, particularly when several symbols for the same referent appear about equally understandable. Consideration of all the factors

which determine the selection of the best, most effective set of symbols was beyond the scope of this report. As a result, the symbols selected must not be

viewed as a set of final recommendations.

Some of the factors which should be addressed in the final design of a set of

industrial safety symbols are: legibility, under both normal and degraded

viewing conditions; conspicuity (ability to attract attention); behavioral

effects as well as accident reduction (field studies); confusability (of the

symbols within a set); reproducibility; cost; and susceptibility to vandalism.

In addition, the set should reflect a consistent graphic style both for the

interior image and the background shape. Both the AIGA (1979) and Follis and

Hammer (1979) have emphasized the need for an integrated, internally consistent

graphic style. Needless to say, the symbols selected as effective representations of the various referents were drawn from a variety of sources and need

to be adapted to a consistent graphic style. Based upon these considerations,

the symbols presented here must be viewed as a preliminary selection which

requires further refinement. The symbols selected can, however, serve as a reasonable basis for the further development of a set of effective industrial

safety symbols.

With all the above reservations in mind, the set of decision rules can now be

discussed. These rules were utilized to select the interior graphic image

for each referent. An additional research project on effective background

(surround) shape (now in progress) will provide criteria for selecting

surround shapes for these images.

Although the criteria are necessarily somewhat arbitrary, they represent a reasonable basis for decision. The minimum criterion for a symbol to be

selected was that it meet the ISO recomendation for understandability. This means at least 85 percent correct definitions and no more than five percent

critical confusions for a given symbol. If no symbol for a referent met these

minimum specifications, no suggested image is given. Leniently scored data were used as the basis for symbol selection; of course, use of the more

stringent scoring criterion would result in the exclusion of more symbols.

85
If more than one symbol for a referent met the ISO recommendations, then the

more frequently understood image was selected. However, a minimum difference

between symbols was required to avoid basing this choice on spurious differences. A minimum difference of six percent was required, since this corre- sponded to approximately plus or minus two standard errors of the mean, or an approximate 95 percent confidence interval.

If two or more candidate symbols still could not be discriminated, the next

decision rule involved correspondence with existing symbol standards. Conformance with existing symbol standards appears to be a worthwhile goal, if the

symbol has met the understandability criteria outlined above. The three most

relevant standards are the DoT (1979) set, the ISO draft international standard

(DIS 3864.3), and the Treasury board of Canada Federal Identity Program (1980).

Since the DoT symbols are finding widespread adoption in the United States,

and appear to be the model for graphic features of a number of additional

symbol sets (FMC, 1978), weight is given to these particular recommendations

where the standards disagree among themselves.

Finally, if the previous criteria could not identify a single image for a referent, the preference data from the present experiment were utilized. The

preference data are useful in that the procedure allowed subjects to choose

whatever criteria seemed important to them. At the same time, it must be

recognized that these criteria may not always be the most appropriate.

Further, the inability of many subjects to give a reason for their preference

choice suggests that their opinions may not have been strong or meaningful.

For these reasons the preference data are considered only as supplementary to

the understandability findings. In actual fact, this final decision rule was seldom involved (see table 6).

Table 6 lists the referent messages, the suggested symbol, if any, for each

referent, and the decision criteria by which the symbol was selected.

Figure 32 illustrates the selected symbols. This selection is made in the

interest of differentiating and capsulizing the performance of the wide variety

of symbols studied. Beginning with the initially collected catalogue of symbols

(section 3.3), several hundred images were subjected to some form of evaluation.

While it is emphasized that limitations exist in the scope of the workplace

sample and the number of factors considered, the final selections are nonetheles

useful as examples of successfully understood symbols and as potential items

to be included in the development of a refined and consistent set of industrial

safety symbols.

6.2 GENERAL CONCLUSIONS

A number of conclusions can be drawn about the data and information reported in

the previous sections. These center around five major issues which include the

1 The standard error for the percentage correct measure can be estimated by

using binomial approximation to the normal curve. Based upon this relationship, the standard error of the proportion of items correct is estimated by

/NPQ/N (where N is the number of subjects per group, P is the proportion

of correct answers, and Q is the proportion of incorrect answers).

86
Table 6

Symbols Selected to Represent each Referent***

REFERENT SYMBOL

Electrical C

Explosion B

Flammable -

Corrosion A

Poison -

Entanglement C

Slip C

Trip/Fall A/C

Overhead C

General Warning

Radiation -

Laser -

Biohazard -

No Smoking B

No Open Flame B

First Aid A

Safety Shower B

***These choices are preliminary, based

population of industrial employees, and

of a complete set of industrial safety

SELECTION BASIS

Only symbol to reach criterion level

Reached criterion: 6% greater than C

No symbol reached criterion

Reached criterion

No symbol reached criterion

Reached criterion

All reached criterion; no 6% difference: C in Canadian standard and

is preference choice

Both reach criterion; two messages

intended

Reached criterion (referent problem

exists —see text)

Does not reach criterion

Does not reach criterion

Does not reach criterion

Does not reach criterion

Both reach criterion: B recommended

by DoT: B is preference choice

All reach criterion: B consistent

with DoT graphic approach for No

Smoking: B is preference

Both reach criterion; A is Canadian,

ISO standard: A is preference choice

Reached criterion (legibility problems

may exist)

upon the specific results from a limited

should NOT be taken as a final recommensymbols

.

87
Table 6 Continued

Symbols Selected to Represent each Referent***

Eyewash - No symbol reached criterion

Fire Extinguisher same Reached criterion

Hose & Reel same Reached criterion

Fire Alarm None reached criterion (referent problem exists)

Head Protection B All reach criterion: C & B 6% above A:

B is Can/ ISO standard: C is preference

choice: recommend redesign of B in

line with Canadian approach

Ear Protection C A St C reached criterion: no 6% difference

C is ISO/ Can Standard: A is preference

choice: recommend redesign of C in line

with Canadian standard

Eye Protection B All reached criterion: B St C 6% greater

than A, B is ISO/ Can standard: C is

preference choice: recommend redesign

of B in line with Canadian standard

Hand Protection A All reach criterion: A 6% greater than

B or C

Foot Protection A All reach criterion: A & B 6% greater

than C: A is ISO standard: C is pref- erence choice: recommend redesign of A

in line with Canadian standard

Respiratory Protection - No symbol reached criterion, unless "gas

mask" answers are included with leniently

scored data for A: recommend redesign

Emergency Exit A* A & C reach criterion: no 6% difference:

B is proposed ISO standard: A is pref- erence choice

*See text p. 77 for a discussion of problems relating to the graphic elements

inherent in the exit symbol imagery. Further research is in progress on the

legibility of exit symbol indications.

88
Table 6 Continued

Symbols Selected to Represent each Referent***

Exit c* Reached criterion level

No Exit - No symbol reached criterion level

No Entry B B barely reaches criterion level due to

large number of answers related to

"stop" or "halt"

Use Stairs in Fire B Both reach criterion level: no 6% difference: no standard exists: B is

preference choice

Forklift Truck A A & C reach criterion: no 6% difference

A is in ISO standard: A is preference

***These choices are preliminary, based upon the specific results from a limited

population of industrial employees, and should NOT be taken as a final recommendation of a complete set of industrial safety symbols

*See text p. 77 for a discussion of problems relating to the graphic elements

inherent in the exit symbol imagery. Further research is in progress on the

legibility of exit symbol indications.
? igure 32

Symbols Selected to Represent each Referent**

ELECTRICAL EXPLOSION FLAMMABLE

CORROSION POISON ENTANGLEMENT

C

SLIP TRIP/ FALL OVERHEAD

**These choices are preliminary, beaserl upon the specific responses of a limited

population of industrial personnel, and should NOT be taken as the final recom- mendation of a complete set of industrial safety symbols. Futher research is in

progress

90
Figure 32 Continued

Symbols Selected to Represent each Referent

GENERAL WARNING RADIATION LASER

BIOHAZARD

FIRST AID

A

NO OPEN FLAME NO SMOKING

B

EYEWASH

91
Figure 32 Continued

Symbols Selected to Represent each Referent

FIRE EXTINGUISHER HOSE AND REEL

HEAD PROTECTION EAR PROTECTION

A

FIRE ALARM

EYE PROTECTION

B

HAND PROTECTION

A

92
Figure 32 Continued

Symbols Selected to Represent each Referent

EMERGENCY EXIT EXIT NO EXIT

93
understandability of the symbols tested and the appropriateness of the referents

and symbols tested; procedural and methodological concerns; scoring criteria;

reliance upon training; and need for further research on industrial safety

symbols

.

The first and foremost issue is that of the understandability of the individual

symbols tested. For most of the referents studied, at least one image was reasonably well understood. Exceptions to this include symbols for radiation,

laser, biohazard, general warning, combustible, eyewash, exit, no exit, no entrance, and fire alarm call point. The first four referents are characterized by very low percentages of correct responses and high degrees of graphic

abstraction. Data obtained in the present experiment suggest that highly

abstract symbols are not particularly well understood. Messages related to

hazard warning and egress generally appear to be more difficult to communicate

effectively than those for protective gear perhaps because of the highly

pictorial and directly representative nature of the graphic images studied for

the latter.

If a general conclusion could be drawn about the kind of graphic image which

communicates its message effectively upon initial viewing, it would be that

pictorial, representational messages often involving a person and the hazard,

action, or piece of gear appear to be most effective. Certainly, the very

abstract images studied in this experiment were generally not identified correctly, often despite long use. (The cross for first aid is an exception, and

even this was correctly identified by only about 90 percent of the subjects.)

On the other hand, the more representational images were generally identified

correctly and often preferred. Inclusion of a person or part of a person so that the consequences are depicted, such as showing the hand in a set of gears

or the hard hat on the head, appears to be an effective approach. These general

conclusions, of course, are inferences drawn from performance on specific

symbols, and as such are necessarily tentative. Nevertheless, a number of

specific symbols emerged as effectively communicating their intended meaning.

Correct definition of a symbol does not necessarily imply, however, that correct

behavior will follow. The effectiveness of symbol and word signs in eliciting

and maintaining safe behavior is a fertile topic for further research.

Ttie data obtained in the present study also indicate that of the 33 referents

tested, only two seemed ineffective or inappropriate for industrial applications. These are "fire alarm call point" and "use stairs, not elevators in case of fire". The former suffers from confusion over whether the intended

meaning is to designate the location of a place where an alarm is turned in or

is to indicate the alarm location itself, as well as whether the purpose of

the alarm is to warn building inhabitants or to notify the fire department.

Greater precision in defining the intended meaning is needed for these various

concepts before an effective symbol can be developed. The other message which

concerns the use of stairs, rather than elevators during a fire would be applicable only to those industrial sites which possess elevators. Symbols for two

other referents, "overhead hazard" and "fall", appeared to convey at least two

messages — "machinery in operation overhead" and "falling objects likely” with

"wear hard hat" as a possible third message. "Fall" can be separated into two

messages, "trip-over an object" and "fall from elevation."

94
The potential refinement in referents points to a philosophical problem with

symbols. If one accepts the premise that more representative symbols communicate

more effectively, how specific or representative should the resulting image be?

It is obviously more efficient to use a generic image to indicate a class of

message than to use a specific image to indicate each member of this class.

The generic approach is clearly the one taken by the various international

standards. For example, a "circle, slash and cigarette" means "no smoking" of

anything, even though pipes and cigars are not depicted. A "head with glasses" means "wear eye protection" leaving the kind of protective device up to the

user, although instances may exist for which a more specific symbol, such as "wear goggles", is desirable. Determining the effectiveness of every proposed

message and symbol combination was clearly an impossible task for this study.

Instead, the messages that appeared to be most critical from the sources given

in section 3 were studied in the hope that this information, albeit limited,

would prove useful to those concerned with industrial symbols. The use of

many, specific images depicting a set of limited messages may potentially

confuse the user, who is forced to distinguish between very similar images.

The end concern must always be for the users and the effectiveness of the

message in communicating with them.

Another issue that emerged in the course of the present study is that of

methodological procedures. The experimental approach followed for this report,

is in some ways a "worst case" situation. Although the instructions indicated

that the symbols were all related to industrial hazards and safety, no specific

context was provided for the individual symbols. There were several reasons

for this procedure. First, since context may provide additional information,

testing the symbol by itself is a conservative, or "worst case" procedure.

Secondly, as discussed in section 3.2, it may not be possible to find a single

context that is representative for a symbol, especially across factories and

industries. A context unfamiliar to a worker or inappropriate to his industry

could even interfere with communication. Finally, in actual usage, an observer

might simply not be attentive to the context in a given encounter with a sign.

This is especially important given the relatively high injury rate for new

workers. Issues related to context and familiarity remain important, and can

be seen in the somewhat poorer performance of the naive participants on workplace specific messages such as eyewash and ear protection.

Other considerations that emerged as a result of the experimental procedure

are related to scoring concerns. Although the use of a definition procedure

is one of the best ways to obtain confusions and inappropriate responses, it is

sometimes difficult to determine what a subject meant by a particular answer.

As an example, for the ear protection symbols, "wear headphones" was a frequent

answer. Did the subjects mean "wear communication headsets," or "stereo headsets" or did they simply not know the correct term for ear protection? Similarly,

for "combustible", answers emerged which were related to the presence, rather

than the likelihood, of fire. It is unlikely that subjects really expect these

fire symbols to be stored away, only to be put up in the case of a fire. Yet,

their answers do not indicate an awareness of the idea that "something might

catch on fire". These scoring problems might not be elicited with a different

procedure—but the confusions also might not emerge.

93
Another issue related to scoring difficulties concerns the problems that some participants had with simply writing down definitions. At least one site

studied contained a large number of people who were not at all skilled at

written tasks, although they were technically literate. Although they may have

understood the symbol, they had great trouble expressing themselves so that the

raters could decipher their intent. Problems of poor handwriting and verbal

incoherence abounded. In addition, decisions about subtle distinctions required

during scoring can lead to substantial differences between scorers, or even

for the same rater at two different times. The procedure described in section

4.3.7 was designed to minimize inconsistencies. In some cases, review of the

pilot study protocols led to slightly revised scoring criteria for the main

experiment, which produced clear differences in results. In addition to the

difficulties involved in scoring the responses, the volume of data obtained was somewhat overwhelming and requied considerable time commitment. Use of a multiple choice procedure using confidence ratings could avoid some of these

problems (Lerner and Collins, 1980).

An unanticipated finding from the present experiment was the relatively poor

performance of several symbols that have been widely used for some years and

with which industrial personnel might reasonably be expected to be familiar.

These include the DoT/UN symbols for flammable, electricity, poison, and radiation, as well as the DoT symbol for no entry. Each of these symbols was identified correctly by fewer than 75 percent of the industrial personnel tested.

Yet, these symbols are widely used on industrial containers and trucks, so that they should have been somewhat familiar. The difficulty of teaching the

meaning of abstract symbols is underscored by the poor performance of the

radiation and the DoT "no entry” symbols. Long use of these symbols has not

led to good comprehension as measured by the experimental procedures used in

this report. The relatively poor performance of these symbols suggests the

need to evaluate symbol performance, in terms of understandability , before

adoption of a symbol standard. It also suggests that informal training through

the simultaneous presentation of a symbol with a word label may not be particularly effective, at least for these symbols. The issue of training remains

largely unresolved. For example, Griffith and Actkinson (1978) found that

varying the type of training method did not appear to improve performance for

the highway symbols that they tested. As a result, it is of critical importance

to determine the initial understandability of any symbols designed to warn of

industrial hazards or to provide safety information. Furthermore, if a training

program is employed, it could focus on teaching safe performance, using the

symbols as reinforcement and increasing already good comprehension, rather

than "teaching" obscure or unfamiliar imagery.

Throughout the preceding paragraphs, understandability has been treated as though it were a clearly defined entity. Because it is not, a criterion of 85

percent correct responses was set as a tentative cut-off value below which a symbol could be said not to communicate. Similarly 5 percent critical confusions was also suggested as a cut off to eliminate those symbols for which

substantial misconception and inversion exist. These values were adopted from

standards groups and previous studies; although they appear reasonable, the

criteria are by necessity arbitrary and subject to discussion. For example,

96
adoption of more lenient or stringent criteria is certainly possible.

Conceivably, the level of hazard or potential danger to the user could be used

as an index by which to set a criterion. Symbols for more dangerous situations

could require a higher percentage correct, for example, before they are used as the sole hazard-warning message. More lenient criteria could be selected if

training were provided, or additional verbal material added, or if workers were familiarized with the symbols and the intended hazards. Selection of an acceptable criterion cut-off appears to depend on the criticality of the message,

as well as on opportunities for training or providing additional verbal material.

This study systematically identified those workplace messages which require a standard symbol image and then attempted to select the most suitable image from

a set of candidates for each referent. The results of the experiment suggest

some general findings, but a number of questions remain unanswered relating to

the effectiveness of industrial safety symbols. Data presented in this report

represent the responses of a limited set of industrial and non-industrial

personnel. As such, they provide an indication of, but not the final assessment of workplace safety symbol effectiveness. A number of general research

questions also remain to be addressed. First, the effectiveness of both symbol

surround shape and color in encoding hazard and safety information must be

addressed. While these did not appear to have a great impact upon the percentage of correct answers to a symbolic image, subjects' comments indicated an awareness of some coding elements; specifically, yellow for caution, red for

danger, fire and red cross, triangle for hazard warnings, and circle and slash

for prohibition. In regard to the triangle, the question arises as to whether

this shape conveys enough information about the presence of a hazard to offset

its reduction of the area occupied by the image. Would another shape such as a diamond or octagon convey the same type of hazard warning? Such a question

can only be answered by a combination of laboratory visibility research and

field research on perceived hazardousness. Secondly, images eliciting a high

percentage of correct answers should be studied further to determine their

detectability and discriminability under reduced visibility conditions. Many

of the signs surveyed during the site visits were often dusty and partially

obscured. Selection of the most legible symbol to allow maximum opportunity

for detection would appear appropriate, when combined with data on symbol

comprehension. A third area for further research involves a comparison of the

effectiveness of word and symbol signs in achieving the desired safe behavior.

Which signing approach, word only or symbol only, is more effective, or is a combination of both, the most effective?

Finally, there is a great need to develop a consistent set of safety symbols,

designed according to consistent graphic principles such as those suggesed by

the AIGA (1974) and evaluated according to both field and laboratory procedures.

The data reported in this report provide a good indication of the messages

required as well as an initial assessment of several symbols for each of these

messages. The final set of symbols should then be assessed with industrial

personnel to determine overall understability and in a laboratory to evaluate

visibility. In this way, the most effective set of symbols for hazard warnings

and safety messages can be used, to increase the safety of those in the

industrial workplace.

97
REFERENCES

1. American Institute of Graphic Arts (AIGA) , Symbol Signs. Report prepared

for the Department of Transportation. DOT-OS-40192, November 1974.

2. American Institute of Graphic Artists (AIGA), The Development of Passenger/

Pedestrian Oriented Symbols for Use in Transportation-Related Facilities,

U.S. Department of Transportation, DOT-RSPA-DPB-40-79 , 1979.

3. American National Standards Institute (ANSI). Safety color code for marking

physical hazards, 253.1, 1979.

4. Baldwin, C. L. and Runkle, R. S., Biohazard symbol: Development of a biological hazards warning signal. Science , 158, 1967, 264-265.

5. Brainard, R. W., Campbell, R. J., and Elkins, E. H. , Design and

Interpretability of Road Signs, Journal of Applied Psychology, 1961, 45,

130-136. ~

6. Bureau of Labor Statistics, Occupational Injuries and Illnesses for 1978,

USDL 79-788; and Work Related Deaths for 1978, USDL 79-787, Nov. 7, 1979.

7. Cahill, M. C., Interpretability of Graphic Symbols as a Function of Context

and Experience Factors, Journal of Applied Psychology , 1975, ji>0, 376-580.

8. Cahill, M. C. , Design Features of Graphic Symbols Varying in Interpretability, Perceptual and Motor Skills , 1976, ^2, 647-653.

9. Canadian Standards Association, Signs and Symbols for the Occupational

Environment, Can. 3-Z-321-77, September 1977.

10. Collins, B. L. and Pierman, B. C. , Establishing Ways to Decide Whether

People Understand Symbols, Industrial Design , 1979, J26, 48-50.

11. Collins, B. L. and Lerner, N. D., Assessment of fire safety symbols,

Human Factors , 1982, 24, 75-84.

12. Deraber, W. N. and Warm, J. S., Ps ychology of Perce ption , 2nd Edition, New

York: Holt, Rinehart & Winston, 1979.

13. Dewar, R. E., The Slash Obscures the Symbol on Prohibitive Traffic Signs,

Human Factors , 1976, JL8>, 253-258.

14. Dewar, R. E. and Ells, J. G., The Semantic Differential as an Index of

Traffic Sign Perception and Comprehension, Human Factors, 1977, 19, 183-

189.

15. Dewar, R. E., Ells, J. G., and Mundy, G., Reaction Time as an Index of

Traffic Sign Perception, Human Factors, 1976, 381-392.

98
16.

Dewar, R. E. and Swanson, H. A., Recognition of Traffic Control Signs,

National Academy of Sciences, NRC Highway Research Board Bulletin , 1972,

414, 16-23.

17. Dreyfuss, H., Case Study: Symbols for Industrial Use, in G. Kepes (ed.)

Sign , Image and Symbol , New York: George Braziller, 1966, pp. 126-133.

18. Dreyfuss, H., Symbol Sourcebook , McGraw Hill, New York, 1972.

19. Easter by, R. S. and Hakiel , S. R., Safety Labeling of Consumer Products - Interim Report on Shape and Colour Coding of Signs , AP Report No. 56,

Applied Psychology Department, University of Aston in Birmingham, Gosta

Green, Birmingham, England, March 1977(a).

20. Easterby, R. S. and Hakiel, S. R. , Safety Labeling of Consumer Products:

Shapes and Colour Code Stereotypes in the Design of Signs , AP Report 75,

Applied Psychology Department, University of Aston in Birmingham, Gosta

Green, Birmingham, England, December 1977(b).

21. Easterby, R. S. and Hakiel, S. R., Safety Labeling and Consumer Products:

Field Studies of Sign Recognition , AP Report 76, Applied Psychology

Department, University of Aston in Birmingham, Gosta Green, Birmingham,

England, December 1977(c)

22. Easterby, R. S. and Zwaga, H. I. G., Evaluation of Public Information

Symbols, ISO Tests: 1975 Series , AP Report 60, Applied Psychology

Department, University of Aston in Birmingham, Gosta Green, Birmingham,

England, March 1976.

23. Ells, J. G. and Dewar, R. E., Rapid Comprehension of Verbal and Symbolic

Traffic Sign Messages, Human Factors , 1979, 2K 161-168.

24. Follis, J. and Hammer, I., Architectural Signing and Graphics, New York:

Whitney Library of Design, 1979.

25. Forbes, T. W., Gervais , E., and Allen, T., Effectiveness of Symbols for

Lane Control Signals, Highway Research Board Bulletin, 1963, 244 , 16-29.

26. Freedman, M. and Berkowitz, M. S., Preliminary Report on Laboratory and

Pilot Field Testing: Testing Criteria and Techniques of Evaluation for

Passenger/ Pedestrian Oriented Symbols for Use in Transportation Related

Facilities , DOT-OS-60071. FIRL No. C4448, January 1977.

27. Freedman, M. , Berkowitz, M. S., and Gallagher, V. P., Symbol Signs

:

Testing Criteria and Techniques of Evaluation Passenger/Pedestrian

Oriented Symbols for Use in Transportation Related Facilities , Interim

Report, U.S. DoT, September 2, 1976.

28. FMJ, Product Safety Signs and Labels, FMC: Santa Clara, California,

2nd Ed .

,

1978.

99
#

29. Green, P., Development of Pictographic Symbols for Vehicle Controls and

Displays," Society of Automotive Engineers: Technical Paper (Warrendale,

PA), #790 383, February-March 1979.

30. Green, P. and Davis, G., The Recognition Time of Rotated Pictographic

Symbols for Automobile Controls, Journal of Safety Research, 1976, 8, 179-

183 . “

31. Green, P. and Pew, R. W., Evaluating Pictographic Symbols: An Automotive

Application, Human Factors , 1978, 20, 103-114.

32. Griffith, D. and Actkinson, T. R., International Road Signs:

Interpretability and Training Techniques, Proceedings of the Human Factors

Society - 21st Annual Meeting , 1977, pp. 392-395.

33. Griffith, D. and Actkinson, T. R., International Road Signs

:

Interpretability and Training Techniques , U.S. Army Research Institute

for the Behavioral and Social Sciences - Report 1202, September 1978.

34. Heard, E. A., Symbol Study - 1972 , Society of Automotive Engineers,

Automotive Engineers Congress, Detroit, MI, February 25 - March 1, 1974,

740-304.

35. International Organization for Standardization (ISO), Equipment for fire

protection and fire fighting safety signs, Geneva: ISO, Draft Proposal

DP 6309, 1S0/TC 21/SC /, 1978.

36. International Organization for Standardization (ISO), Safety Colours and

Safety Signs, Geneva: ISO, Draft Standard, DS 3864.3, ISO/TC 80, 1978.

37. Janda, H. F. and Volk, W. N., Effectiveness of Various Highway Signs,

National Research Council - Highway Research Board Proceedings, 1934, 14,

442-447.

38. King, L. E., A Laboratory Comparison of Symbol and Word Roadway Signs,

Traffic Engineering and Control , No. 12, 1971, pp. 518-520.

39. King, L. E., Recognition of Symbol and Word Traffic Signs, Journal of

Safety Research , 1975, 7, 80-84.

40. King, L. E. and Tierney, W. S., Glance Legibility - Symbol Versus Word

Highway Signs, paper presented at the 1970 Annual Meeting of the Human

Factors Society, San Francisco, October 1970.

41. Kirsh, I., and Guthrie, J., The Concept and Measurement of Functional

Literacy, Reading Research Quarterly , 1977-78, 13, 485-507.

42. Kolers, P. A., Some Formal Characteristics of Pictograms, American

Scientist , 1969, 57, 348-363.

100
J9k *

43. Laner, S. and Sell, R. G., An Experiment on the Effect of Specially

designed safety posters, Occupat ional Psychology, 1960, 34, 153-169.

44. Lerner, N. D. and Collins, B. L., The Assessment of Safety Symbol

Understandability by Different Testing Methods, NBSIR 80-2088, 1980.

45. Lerner, N. D. and Collins, B. L., Workplace Safety Symbols, National

Bureau of Standards, NBSIR 80-2003, 1980.

46. Mead, M. and Modley, R., Communication Among All People Everywhere,

Natural History , 1968, 77 , 56-63.

47. Modley, R. , Graphic Symbols for World-Wide Communication, in G. Kepes

(ed.) Sign, Image and Symbol, New York: George Braziller, 1966,

pp. 103-125.

48. Modley, R. and Myers, W. R., Handbook of Pictorial Symbols , New York:

Dover Publications, 1976.

49. National Safety Council, Accident Facts: 1979 Edition , National Safety

Council, Chicago, 1979.

50. Plummer, R. W., Minarch, J. J., and King, E. L., Evaluation of Driver

Comprehension of Word Versus Symbol Highway Signs, Proceedings of Human

Factors Society 19th Annual Meeting , 1974, pp. 202-208.

51. Schiff, W., Perception: An Applied Approach, Boston: Houghton Mifflin,

1980.

52. Smillie, R. J., Continuing Research in Job Performance Aids: The

Interaction of Speed Stress and Media, Proceedings of the Human Factors

Society 22nd Annual Meeting , 1978, pp. 502-506.

53. Smith, G. and Weir, R. , Laboratory Visibility Studies of Directional

Symbols Used for Traffic Controls Signals. Ergonomics , 1978, 21, 247-252.

54. Standards Association of Australia; The Design and Use of Graphic Symbols

and Public Information Standards, Part 3, Test Procedures for Evaluating

Graphic Symbols and Symbol Signs, Australian Standard, AS 2342, Part 3,

1980.

55. Treasury Board Canada, Graphic Symbols for Public Areas and Occupational

Environments , Ottawa, Canada, July 1980.

56. Walker, R. E., Nicolay, R. C. , and Stearns, C. R. , Comparative Accuracy of

Recognizing American and International Road Signs, Journal of Applied

Psychology , 1965, 4^, 322-325.

57. Washington Post, "Reading and Writing Gap Widening as Needs Out-distance

Skills in U.S.", September 9, 1979, p. 12.

101
58. Wiegand, D. and Glumm, M.M., An Evaluation of Pictographic Symbols

for Controls and Displays in Road Vehicles, Technical Memorandum 1-79,

U.S. Army Human Engineering Laboratory, February 1979.

59. Zwaga, H. J. G., Results of ISO testing programs, personal communication,

1981.

102
Appendix A

Details of Experimental Procedure Including Instructions to Instructions

to the Participants

Appendix A presents the three orders of symbol images, giving the symbol number

arbitrarily assigned by the experimenters, the intended referent, and the image

content. The order of presentation of the symbols within each group was randomized for each group of participants. Each group of participants saw only one

order, with the exception of one small group of participants in the main experiment, and the participants from the Gaithersburg area in the pilot.

Appendix A also presents the general procedure for Administering the experiment,

including the briefing forms.

103
Appendix A

Group 1 Images

Symbol

Number* Referent Image

2B Warning flame ISO - flames in triangle

9 C Electricity FMC - hand, wire

12C Explosion ISO - triangle and explosion

15 C Fork lift truck Alone

17B Safety shower Man in shower

6 Biohazard

23 C Safety shoes Putting on shoe

26 C Eyewash Eye w/ spray

28B Safety gloves 1 glove

33B Respirator Alone - yellow

35B Corrosion Bandaged hand

79 Fire Extinguisher

31 Respirator ISO - face mask on face

41A Hard hat Putting on hard hat

45B Entanglement Gears, arrow ! 50C Ear protection ISO - head w/muffs

51A No open flame Flame, triangle, slash

60B First aid Hand, cross

57B Safety glasses ISO - glasses on head

39A Poison Mr. Yuk

63 C Overhead hazard Hard hat, arrow

67 B Exit Dot

69B No exit Man, door, slash

74C No entry Standing man, slash

76A Slip hazard Boot, squiggle

81A Fall Boot in hole

85B Alarm Sounder and hammer

89 C Emergency exit Flames, figure, arrow

38B No smoking Dot - cigarette burning on

right of slash

* The symbol number was arbitrarily assigned to each symbolic image. The

letters A, B, and C refer to the image variant studied for each referent.

Groups 1, 2, and 3 refer to the 3 separate image sets that were used.

Generally, a given participant saw items from only one of the 3 groups.

1 j4
Appendix A

Group 2 Images

Number Referent Image

3C Warning flame Red fire

8B Electricity Zig Zag

10A Explosion Stylized

14B Fork lift truck Driver and bystander

18C Safety shower Torso plus drops

4 Laser

21

A

Safety shoes ISO - 2 shoes

25B Eyewash Eye with drops

29 C Safety gloves ISO - 2 gloves

30A Respirator ISO - face and mask

34A Corrosive DoT - hand and test tube

80 Standpipe

87 Emergency exit Door, arrow, figure running

42B Hard hat ISO - hat on head

46C Entanglement Hand in gears - FMC

48 B Ear protection Muffs alone

52B No open flame Match, slash, - stylized

20B Do not use elevator Flame, figure, stair, elevator

56A Safety glasses Glasses alone

40B Poison Skull and crossbones

61

A

Overhead hazard Circle and triangle

64A Exit

70C No exit Man, door, X

71

A

No entry DoT

77 B Slip Feet, squiggle

83C Fall FMC - figure, ledge

84A Alarm Bell

88B Emergency exit ISO - man, door

55B Warning X in triangle

105
Appendix Items

Group 3 Images

Number Referent Image

1A Combustible Stick in fire

7A Electricity ISO

1 1

B

Explosion FMC

13A Fork lift truck w/d river

16A Safety shower Showerhead w/drops

5 Radiation

22 B Safety shoes 1 shoe

24A Eyewash Head w/drops

27 A Safety gloves Hand putting on gloves

32C Respirator Head and mask

36 C Corrosion Drops and hand

49 Noise hazard Ear and waves

19 A Do not use elevator Flame and figure

43C Hard hat Hat alone

44A Entanglement Gears

47A Ear protection Putting muffs on 53C No open flame ISO match

59 A First aid Cross

58 C Safety glasses Goggles alone

37 A No smoking ISO

62B Overhead hazard Crane load

66C Exit

68A No exit Man walking away from

72B No entry Man w/big hand

78C Slip hazard Man falling - surface

82B Fall/Trip Figure falling

86C Alarm Phone and flame

90A Emergency exit flames, figure, door

54A Warning A!

106
APPENDIX

3 Symbols

Number of Symbols tested per Referent

Main Experiment

2 Symbols 1 Symbol

explain

electrical

corrosion

flammable

overhead hazard

slip

trip/fall

fork lift

entangle

eye

head

hand

foot

no open flame

safety shower

eye wash

fire alarm

exit ( Pour for pilot) no exit

no entry ( Five for pilot)

poison

general warning

no smoking

first aid

stair in fire

radiation

laser

biohazard

fire exit

hose

4 Symbols

hearing

respiratory

emergency exit ( Fiye for pilot)

20
Procedure for Administering NIOSH Experiment

During Experiment

1. Have subjects read and sign subject participation form—(protects us and

them, says experiment should be safe, get them medical attention if accident occurs).

2. Have subjects read and initial privacy act form—(says their data will

never be identified with them).

3. Read Briefing Form — purpose of experiment.

4. Pass out answer sheet for Part 1; ask them to read instructions.

5. Read Briefing, Part 1 —show example of knife & fork, work example. Ask

for questions.

6. Show slides about one every 30 sec. Speed up as all subjects complete

answers

.

7. After part 1 ends allow a short (5 minutes) break.

8. Pass out Part 2—do not pass out 1 & 2 together as 2 has answers for 1.

Allow subjects to read instructions.

9. Read Briefing, Part 2.

10. Show combined symbols—-allow 30 sec. to 2 min. to complete per symbol (too

long and will get novels on these symbols). Again speed up as subjects

learn the task.

11. Collect forms.

12. Read debriefing—answer questions, provide additional information as desired

.

13. If subjects can't write English you fill in the answer sheet for them—try

hard not to guide them or react positively or negatively.

14. If time is very short, drop preference portion, or skip "why" part. Just

have them indicate appropriate letter. Try to run preference part, as this can provide valuable information to us.

108
Appendix R

Wrong and Partially Correct Answers from the Main Study for each

Referent and Symbol Combination

Appendix B presents a tabulation of all wrong and partially correct answers obtained during the Main study. A frequency count of the number of times

each response occurred is also given. The P refers to Partially correct

answers; the X refers to answers that were scored as wrong. The symbol

numbers are the same as those given in Appendix A, while the alphabetic

characters (A, B, or C) are the same as in both A and the Figures 1-31.

109
APPENDIX C

Table 1

Wrong, Partial Answers NIOSH Experienced Ss

WARNING - FLAMMABLE

Partial Wrong

Symbol* Symbol*

No. No

.

1A f req

.

1A freq

.

No lighted matches, open flame 17 Fire present in area 10

No smoking area 4 Hot , high temperature 3

Fire area 3 Smoking area 2 Don't throw matches 2 Chemical fire, danger 2 Dangerous flammable chemical 2 Non-flammable material 1 Temperature activated materials 1 Plane 1 Electrical 1

29P 20X

2B 2B

Fire area 11 Fire present in area 30

Danger, fires 5 Fires permitted 6

No open flame 5 Fire extinguisher 2 Caution, smoking 1 Camping 1 Fire safety 1

22P 40X

3C 3C

Fire area 10 Fire, open flames 24

Don't play with fire 1 Extreme heat 6

Flame hazard 1 Watch for fire 3 Fire protection 1

12P 34X

LASER

Partial Wrong

#4 #4

Caution, bright lights 18 Radiation area 8

Shades, sunglasses required 3 Caution sunshine, glare 8

Ultraviolet 1 Explosion, explosive 5 Caution, welding 3 High voltage, wires 3

Solar energy plant 2 Snow area 2 Flying debris 2 No light allowed 2 Hot - acid 1 Lights required 1 Wear suntan lotion 1 Target practice 1

22P 39X

*Symbol numbers are the same as in appendix A; alphabetic characters are also the same as in figures 1-31. 1

-i q
BIOHAZARD

PARTIAL WRONG

3 Hazard contaminents 1 5 Radiation 9

Blades, rotating object 6

Flying, falling objects 5 Sharp, cutting objects 4

Moving machinery parts 4

Heavy machinery 3

Spacecraft 2

Multiple outlets 2

Emergency vehicles , area 2 Intersection 2 Birds 1

No bird watching 1

Pulleys 1

Work area 1

Safety lane 1

Low overhead tunnel 1 Volatile chemicals 1

Hidden camera 1

Weird art forms ahead 1

IP 48X

RADIATION

PARTIAL WRONG

6 6 Caution, fans, blades 12

Ventilation system, fan 5

Moving parts , shaft 4

Hearing protection, noise area 3 Fallout shelter 3 Siren 2 Planes in area 1 Mine shaft 1 Three roads 1

Propane gas 1

Lathe machinery 1

34X

ELECTRICITY

PARTIAL WRONG

7A Electrical, area 6 7A Lightning 11

Electric charge, static

electricity 4 Curves, comers, crooked road 5

111
ELECTRICITY (continued)

PARTIAL WRONG

7A Electrical Panel 2 7A Danger below, falling object 4

Electric cable below 1 hazard

Lightning - high voltage 1 Slippery, dangerous floor 3

Do not use electricity 1 Down, go to lower level 2 Electric ground 1

Caution 1 No 1

Signal 1

San Diego Chargers 1 Machinery 1 Hard hat area 1

15P 32X

8B Electric wire 5 8B Lightning 12

Electricity 4 Danger 1 Electric Equipment, panel 3 Stairway 1

- - 12P 14X

9C Electrical device, contact 2 9C Hand danger 2 Electrical 1 Dangerous 1 Electric voltage 1 Do not touch 1

5P 3X

EXPLOSION

PARTIAL WRONG

|0A Blasting area 9 10A Fire, combustible 6

Explosion area 5 Beware of broken glass 2 Star 2 Danger or Disaster area 2 Yield right of way 1 Bomb shelter 1 Location park 1 Loud noise area 1

14P 16X

j i R Explosion area 16 Flammable, fires 5 Blasting area 6 Caution, high tension 1 electricity

Danger 1 Hazard area 1

22P 8X

112
EXPLOSION (continued)

PARTIAL WRONG

,2C Blasting Zone 17 12C Breakable, shattered glass 3 Explosion area 14 Flying stone, gravel 2 hazardous storage 1 Eye hazard 1 Gloves area 1 Loud noise 1

32P 8X

FORK LIFT TRUCK HAZARD

PARTIAL WRONG

, Tow motor, fork truck

x3A _ . Truck crossing

4 Don't pickup by fork lift

Material handling area

1

2 1 Equipment in use 2 Tow motor driver 2 Loading area 2 Yield to equipment 1

Slow moving forklift 1

14P 2X

14B Truck, equipment crossing. 9 14B Men working (watch for) 7

roadway Dangerous work area 2

Moving vehicles, equipment 8 Use truck lift 2 Loading area 7 Drive carefully 1

Watch step 2 Do not carry load too high 1 Fork lift 1 Fork lifts only 1

Machinery area 1 Material handling area 1

28P 15X

Tow motor, forklift 10 15c Forks down or too high 2 Loading, unloading area 6 Don't use fork lift 1

Vehicle road, crossing 2 Use fork lift 1

Yield to fork lifts 2 Warehouse 1

Fork lift drivers in area 1 Material handling area 1

Moving equipment 1 PRT station loading 1

22P 7X

113
SAFETY SHOWER

PARTIAL WRONG

16A shower 30 16A sprinkler system control 6

Falling water, wet area 6

School zone 1 Light broken 1

Wear water protective gear 1 Magnets being used 1

Poor lighting 1

Area of Spillage 1

Overhead crane 1

Acid 1 Bench area 1

3 OP 21X

17 B Shower 31 17 B Water pipes 1 Shower, pull down handle 9

Contamination clean-up area 1

4 IP IX

18c Shower 35 18C Sun lamp, bright lights 3

Wash area 1 Watch for falling objects 2 Eye wash Shower room, bathroom 2 Low light area 1

Correct lighting on job 1 Wet 1

For fire 1 Cleanliness 1

12X 1 ")Y

DO NOT USE ELEVATOR IN CASE OF FIRE

PARTIAL WRONG

19A ^

re Fireescape 34 , Get out, leave

Watch out for fires, danger

3 stairs 23 2 Fire exit 11 Do not run down stairway in 2 This is exit 1 fire

Go for help 1 Slippery, inflammable 1

69P 9X

114
DO NOT USE ELEVATOR IN CASE OF FIRE (continued)

PARTIAL WRONG

2 Qg No fire exit 8 20B Fi r© exit, blocked 5 Fire exit 5 Do not enter 3

Do not use elevator 4 Do not use 1

Fire escape 2 Fire hazard 1 Use stairs 2 House fire 1 May not be used in fire 2 Blind man 1

23P 12X

SAFETY SHOES

PARTIAL WRONG

21A

Hard toe boots 4 . Leave boots, shoes here

21A

1 Safety Shoes 4

Boots required 3

Shoes required 3

14P IX

22B Wear your boots 17 22B Safety 1

Safety shoes 7 Walking trail 1

boots 2 Shipping and loading 1

Shoe store 1

26P 4X

23C Wear boots 29 23C Rubber boots required 11

Protective footgear 4 Wear hip boots 1 Caught in drive chain 1

33P 13X

EYEWASH

PARTIAL WRONG

24A Wash eyes 1

2 ^ Water fountain 5 Face wash present 1 Eye & nose are running 3

Wash area 1 Witch for eyes, mouth 2

Overhead hazard area 2 Weighing scales 2 Oil chain 1

Respirator needed 1

Liquid flow 1

Hoist block & fall 1

Hot metal or crane 1

Toilet 1

3P 2 OX

115
EYEWASH (continued)

PARTIAL WRONG

25B Eye Sprinkles 1 25B Eye irritation, danger 11

Wear eye protection 11

Do not rub eye 1 Water spraying 1 Kleenex 1

IP 25X

26C Eye washing 1

26C Eye protection should be worn 16

Wash eye out in emergency 1 Eye hazard, material 12

splashing

Someone watching you 3 Blinding light 1 Slippery when wet 1

Gas pump 1

2P 34X

SAFETY GLOVES

PARTIAL WRONG

27A Work, safety, gloves 5 21k Acid or hot 1 Rubber gloves required 3 Crane signal 1 Hand protection 1 Washing facility 1

High voltage gloves 1

Protective gear required 1

IIP 3X

28B Gloves 1 28B Direction, follow 2 Rubber gloves required 3 Stop 5 Protective equipment 1 Left turn 2 Safety sock 1 White glove test 1 Work area 1 Glove storage 1 friendly people 1

6P 13X

29C Work, safety gloves 4 2 gQWash your hand 2 Use rubber gloves 2 Handle with care 1

Sanitation, wear gloves 1 Watch fingers, hands 1 Hot area 1

7P 5X

116
RESPIRATORY PROTECTION

PARTIAL WRONG

3'JA Noxious fumes , dangerous 19 30A Dust 1 pollutants Water hose, no 1 Respirator, safety mask 2

2 IP 2X

31 Face protection, mask must 6 31 Sand blasting area 1

be worn Painting or spraying 1 Nose protection, mask. 4

respirator

Breathing protection 2

12P 2X

32C Gas, toxic fumes, unsafe air 17 32C Chemical hazard 1

Mask required 1

Breathing equipment 1 Safety mask 1

Gas mask location 1

2 IP IX

33B Respirator, gas mask location 6 33B Scuba gear, diving 4

Chest protection required 2 No space crafts 1 Wear head, face protection 2 Robot ahead 1 Breathing Apparatus 2 Electronic gear 1 Welding mask 1 Train area 1

Oxygen required 1 Street light ahead 1

Tunnel, turn on lights 1 Wet place 1

Goggle protection required 1

14P 12X

DANGER, CORROSIVE HAZARD

PARTIAL WRONG

Acid 7 Treatment of hand injuries 1

Q A A , # Location of chemicals 3 34A Laboratory 1

Do not touch, hand danger 2

' ash hands 1

12P 3X

117
DANGER, CORROSIVE HAZARD (continued)

PARTIAL WRONG

35B High hand hazard area 14 35B First Aid 36

Watch getting hand burned 1 Danger, pinch points 5 machinery

Turn, left, right 5 Danger, think 4

Stop, halt 4

Bandaged hand 4

Hand danger, injuries 2 Emergency 1 Palm reading 1 Unprotected hands 1 Safety gloves 1 Steel construction area 1 Ho Jos 1

15P 66X

36C Acid 8 36C Caution , sharp , cutting 5 Dangerous area for hands 2 machinery

Use gloves 2 Emergency hand wash area 4

Acid wash area 1 First aid 3

Raw cut 1

Asbestos protection 1

13P 14X

NO SMOKING

PARTIAL WRONG

37A No Cigarettes 1 37A Lit Butt 1

IP IX

38B None 38B Cigarette Smoke 1 Smoking Area 1

2X

118
POISON

PARTIAL WRONG

39A Caution, toxic, chemical fumes 3 39A Bad day, unpleasant area. 11

Bad water 3 ugly faces , unhappy people

Do not eat or drink 1 Gas , fumes in the area 6

Caution, bad taste, bad food 5

Hazard or vomit areas 3

Danger, caution 3

Smile, good attitude 2 Poison center 1 Face protection 1

Need lights 1 Sun exposure 1 Face mask area 1

Desert area, no water 1 Moving rollers 1 Ghost area 1 Cafeteria ahead 1

No licking your eyebrows 1

7P 40X

40B Danger, may cause death 1 40B danger 18

Death, if you enter 1 Yield to elderly 1

IP 20X

HARD HAT REQUIRED

PARTIAL WRONG

41A

Hard hat 2 Wear hair protection

41 A Dressing area

21

Respirator area 1 Ear protection 1

Hold onto hat 1

Safety gear 1 Somebody broke their heart 1

Watch for robbers 1

2P 9X

42B Hard hat 9 42B Construction worker 1 Head protection 1

Wear hat 1

IIP IX

119
HARD HAT REQUIRED (continued)

PARTIAL WRONG

43C Hard hat 7 43C Safety glove -dangerous 1

Protective headgear 2

9P IX

ENTANGLEMENT

PARTIAL WRONG

Moving gears

Look out for machines

5 , , , Machinery in use Machine shop15

5 1 Guard gears 1

Caution, shut machine off 1

Unsafe Equipment 1

Rotating machinery 1

Observe machine shop precautions 1

15P 16X

45B Turning rotating wheels 5 45B Turning, rolling objects, 8

Grinder present, be alert 1 circles

Dangerous machinery 1 Think, danger, caution 5 Intersection, no turns 4

Explosives being used 2 Going either or both way 2 Moving fast, slow down 2 Turn around area 2 Machines in area 2 Protective eyegear required 2 Dressing room 2 Safety signals 1

On and Off switches 1 Go in right direction 1 Use walkway only 1 Sex education 1

Congested area 1

7P 36X

46C Be careful with dangerous 8 46C Machinery area 1 machinery

Keep guards, shield closed 3 Do not touch , keep hands out 2 Hands in gears 1 Gears squashing 1 no loose clothing near machinery 1

16P IX

120
EAR PROTECTION REQUIRED

PARTIAL WRONG

47A Ear protection 6 47A Quiet - broadcast on air 1

Head protection 1

eye protection required 1

6P 3X

48B Ear, hearing protection 3 48B Tunnel 3

Ear muffs 1 Hearing aid 1

No U- turns 1 Quiet zone 1

4P 6X

#49 Ear protection 1 #49 Listen 4

Audio alarm, bell ring 2 Sound vibrations 1 Radio waves 1

IP 8X

50C Ear protection 10 50C Hearing (test) 2 CO in single 1

10P 3X

NO OPEN FLAME

PARTIAL WRONG

51A Danger of Fire 13 51A Fire, open flames 4

No smoking 6 No fire hazard 1

No matches , cigarettes

,

3 No flammable material 1

combustibles

Do not fire 1

24P 6X

52B No smoking 10 52B No campfires 1

No matches , f lammables 7 Match 1 Flammable area 3 Watch out for fires 1

Fire, careful 2

22P 3X

121
NO OPEN FLAME (continued)

PARTIAL WRONG

53C No matches, combustibles 12 53C Fire, fire material 2

No smoking 10 No campfires 1

Flammable materials, hazard 3

No fires 2

2 7P 3X

GENERAL WARNING

PARTIAL WRONG

54A Think 2 54A Stop 3

Watch for anything 1 Ball park 2 Remember what we said 1 Excitement area 2 If you are not sure, don't use 1 Overhead in operation 2 it Information/exclamation area 2 Key hole 1 Unfinished road 1

This test 1

5P 14X

55B Don't do whatever you are 1

55B

Restricted area, keep out 25

doing no entry

Dangerous crossing, inter- 18

section

Do not yield 5 dead end, no access, no right 5 of way

Do not proceed, cross 4

Unsafe to use , do not touch 2 Do not 2

Yield, at crossing 3

Don't go far 1

Railroad area 1 Road ahead 1 First aid station 1

No caution 1 Place here 1 No cooking, camping 1

IP 71X

WEAR SAFETY GLASSES

PARTIAL WRONG

56A Safety glasses 9 56A De li- cate work 1 Eye protection 2

IIP IX

122
OVERHEAD HAZARD (continued)

PARTIAL WRONG

61A Restricted area 1 Passage narrows 1

Attention 1

Safe water 1 Safety area, no food or water 1

Pointed objects 1

Sunken light for heliopod 1 Question 1

Base 1

Balance materials 1

Safety triangle 1

3-comer room 1

No mooning 1

Watch out for fast wheelchairs 1

No caution signs ahead 1

Open can of beer 1

IP 54X

Hoisting material area 2 62 £

Broken cable, bad strap 3

Loading area 2 Pick up help 1

Hazardous cargo area 1 Don't pick up by crane 1

Overhead objects 1

Caution, broken lift 1

7P 5X

EXIT

PARTIAL WRONG

64^

One way exit 8 64a 0ne way oniy 15

Go to opening, proceed this way 4 Narrow passageway 8

Bottleneck exit 2 Aisle, walkway, throughway 3

Parking lot exit 1 Enter 2 Entry 1 Turn left 1

Emergency exit right 1 Go slow 1 Doorway for traffic flow 1 Don't block exit 1 Stright ahead 1

Parking area 1 Hi dden doorway 1

18P 34X

63C Hard hat area 40 (33C Dead end 1

Watch head 1 Ventilation draft 1

4 IP 2X

123
WEAR SAFETY GLASSES (continued)

PARTIAL WRONG

57B Safety glasses, eye protection

Wear glasses

Eye glasses

Possible eye damage area

71

11

10X

57B None

58C Eye protection, safety glasses 7 58C Wear mask 1 Safety goggles 4

Eye glasses 1

Flying chips 1 Safety mask required 1

14P IX

FI RSI AID

PARTIAL WRONG

Safety station, department 2 5gA Safety 6

Safety cabinet 1 Crossroad, intersection 4

Hospital/safety zone 1 White, red cross 2

4P 12X

60,B Hand first aid 11 60B Watch fingers , danger 4

Emergency or help 1 Hand safety 2 Hospital 1 Broken finger 1

Red cross helper 1 Be careful 1

5P 8X

OVERHEAD HAZARD

PARTIAL WRONG

61A Overhead work 1 6!A Yield 8

Caution, danger, hazard area 8

Going down , hole 4

Something on floor, watch step 3 Fallout shelter 3 Toxic hazardous materials 3

Radiation 2

Limited visibility, dark area 2 Explosion 1

Caution , machinery 1 Tunnel 1 Direction 1

124
EXIT (continued)

PARTIAL WRONG

675 none 67B Don’t exit, enter 7

Roadway, highway 7

Civil defense, safe shelter 5

Go, straight 4

Don't cross, pass, start 4

Proceed, cross w/caution 2 Divided building, split 2 decision

High flight pad 1

Squeeze hazard 1

Watch out for flying pool 1 balls

Sorry 1

Green sign with white line 1 Slippery, caution 1

Volatile chemical hazard 1

Water outlet 1

Radio active material 1 Railway 1

OK to do something 1

Caution vertical beams 1

No Chinese allowed 1

44X

666 Doorway 2 Men's room 1

This way to door 2 Decontamination station 1

Fire door 1 Dead end 1

Use this door 1

Opening ahead 1

7P 3X

NO EXIT

PARTIAL WRONG

Locked Door 3 Fire Door 15

68A Locked door, do not enter 1 i.'8A Keep door to area locked 14

Secure, protected area or door 6

Prison, jail 5

~^ut, close door 5 Tool room storage 1

Burglar 1

Emergency Exit 1

Entrance 1

Hazard material area 1

4P 50X

125
NO EXIT (continued)

PARTIAL WRONG

Don't use, stair, door 3 No running 10

Do not enter (door) 3 Slippery, tripping hazard 8

No passage, thoroughfare 2 No loafing, standing, waiting 4

No doorway 1 Danger crossing, do not cross 3

Exit, exit slowly 2 Don't go this way 1

Danger, construction 1

Open doorway 1

Danger, stairs 1

9P 3 IX

70C 00 not open, use door 22 70C Shut door in unsafe area 1

Door block or not usable 2 No passage 1

25P IX

NO ENTRY

PARTIAL WRONG

71A Stop 4

71A Hallway, passageway, walkway 5 Wrong way 3 Bright light, red light 4

Danger, stay away 1 Beware, caution, danger 3

No Russians allowed 1 No way out , dead end 2

Red dot 2 Crossroad 1 Low ceiling 2 Red rubberball 1

No turn 1 Caution area, go slow 1 No gum 1 Operation 1 Narrow 1

Stay in the line 1 No smoking 1

Blocking symbol 1

May be safe 1 Eye shield 1 Don't do something 1 Open trench 1

Jap meatball after treaty 1

signed

Un level area 1

9P 34X

126
NO ENTRY (continued)

PARTIAL WRONG

72B Stop, halt 69 72B Quiet, no noise 3

Wear hand and ear protection 2 Slow down 2

Stop, pedestrian crossing 1

Caution , men at work 1

Wash hands 1 No glove area 1

D6n ' t do that 1

69P 12X

Stop, look

No walking

1 Do not cross No running, loitering

2 1 2 Do not open 1 Safety walking 1 Don't step out 1 Wear protective clothes 1

Pedestrians 1

Red cross area 1 Caution, welding area 1

Caution , door opening 1 No elevator 1

3P 12X

SLIP HAZARD

PARTIAL WRONG

76A None 76A Wear boots 3

Danger, snakes may bite 2

Sticky area 1

6X

77B Be careful of material^ things 2 77B Housekeeping, keep area clean 2 on floor Stuff, flood from pipe 1 Loose rug 1 Watch for equipment 1

3P 4X

78C Ice, freeze area 1 78C ^ockj ledge area 2 Watch for trip hazards or 1 Hit hard 1

floor obstructions Disabled person in bed 1 Safety 1 Watch for falling objects 1

Safety belt area 1

2P 7X

127
FIRE EXTINGUISHER

PARTIAL WRONG

FALL

PARTIAL WRONG

81A Stair, steps (falling down) 9 00 £ Boots (rubbers) required 2 Hole in floor 7 Safety shoes required 1 Uneven pavement, floor 4 Applying brake 1

Indented area 1

Hazardous trenches 1

22P 4X

82B Watch for drop off 1 82B Hazard, danger area 3

Danger of falling from area 1 First aid 1

High point 1 Disabled people 1

Climbing 1 Working area 1

3P 7X

83C None 83C Use ladders as needed 1

Guard rails 1

2X

128
FIRE ALARM CALL POINT

PARTIAL WRONG

84A Warning if bell is ringing 6 84A Noise area, use hearing 26

Fire department 2 protection

Fire bell 1 Bells ringing 13

Excessive loud alarm 1 School zone 6

Church, steeple 4

Signal , siren 2 Overhead crane 1

Loud speaker 1 Fire hose 1

Use caution when bell is 1

ringing

10P 55X

Warning bell or signal device 2

OCT)

High noise , use ear 19

Listen for alarm 1 protection

Ring bell with hammer 1 Bell 5 Grinding wheel 4

Machine , notating shaft 2 Fire caution 2 Vibration upon striking 2 Saw/cutting blade 1 Shattering materials 1

Danger sign 1

Work area 1

4P 38X

86C Telephone 2 86C Woman on the phone 1

Emergency, fire emergency 2 Ranger station phone 1

5P IX

EMERGENCY EXIT

PARTIAL WRONG

87B

Use door 2 37B T-v Do not run 7

Open doorway 1 Restrooms 3

Go to nearest exit 1

* v exit 1 Passage 1 To playground 1

Obstacle in way 1

5P 13X

129
EMERGENCY EXIT (continued)

PARTIAL WRONG

88B Doorway 5 88B Don't run 16 r Safe to use door 1 Signal alarm 1

Proceed straight ahead 1 Hurry through door - electric 1 Normal passage 1 eye

Narrow passage 1

Enter 1

8P 2 OX

ggc

Fire protection this way 1 ggc Fire hazard area 4

Turn left in case of fire 1 Run, keep away from fire 3

2P 7X

90A Get out-fast- fire 3 90

A

Fire - run 2 Fire door 1 Beware - fire 2 Dangerous-be ready to exit 1 Fire equipment room 1 Get out 1 Do not open doors if fire 1

5P 7X

130
Appendix C

Tabulated Preference Data and Stated Reasons for Choice

Table C presents the tabulated preference data and the stated reasons given

by the participants for their various choices. These data again derive from

the main experiment, rather than the pilot. The symbol identifiers, such as

A, B, or C, again refer to the identifiers given in figures 1-31. The numbers

following the letters refer to the number of participants choosing each of the

alternative choices. The numbers following the stated reason are the number of

participants giving that particular reason for their choice.

131
HAZARD PREFERENCE DATA

REASONS FOR CHOICES

FIRE HAZARD

A- 12 **

No reason

Flame and matches

Should be red and white

All choices are the same

B-113 **

A-10*s

EXPLOSION HAZARD

**

9 More noticeable, representational 5 1 No reason 3 1 More widely used 1 1 Color h

Best of three 1

B-85

No reason

Clearer, easier to distinguish

Looks like fire

Color and shape (imply caution)

All are good

A, C not good

Good, best symbol

Standard sign

Poor symbol

Should be red

C-93

Red color

No reason

Clearer, more understandable

Nice lines, good visual

unde rstanding

Looks more like fire

None of them

All tell hazard

55

15

5

10

57

6

3

1

5

46

28

6

7

321

Looks more like explosion

No response

Clearer, vivid, easier to

understand

Color (implies hazard)

Liked it better

All bad

Indicates greater hazard

C-124*2 **

No reason

Looks more like explosion

(debris)

More easily understood

Looks good, best sign

Triangle implies caution

Yellow implies caution

Rest are no good

Use red background

can be seen better

16

35

16*2

7

5

5

1

51*3 28

10

10

8

6

54

2

Refers to the number of participants selecting each image. A,B,and C refer

to the image itself as identified earlier in the report.

132
ELECTRICAL HAZARD CORROSION

A- 20

No reason 7

Color and shape 6

Clarity, more noticeable, outline 3

Depicts hazard best 2 Shows area 1

All good 1

B-25

No reason 9

Looks like electricity, sparks 5

Large and clear 5

Looks like lightning 3

Significance already established 2 Don ' t like A or C 1

C-176

Hand and wire 51

Wire, hot wire, shows electrical 40

Better graphics, explicit design 15

Other symbols don't look like 9

electricity

More understandable 21

Do not come into contact with - 9

turn off power

No reason 24

Like better 5 Show in black and yellow triangle 1 More commonly used 1

A-173^

No reason 55

Clearer, more believable 30

Shows consequences 11^

Color 6

Surround shape 3

Shows chemicals dripping 14

Shows two types of hazards 27

Testtube alerts to hazard 5 Best 8

All could be improved 2 Red would be better 1 More symbolic 4 Others look like cuts 1 Standardized symbol 6

B-4

No reason

C-39%

No reason 20

More descriptive, understandable 6

Larger concentration of effect 7 Shows consequences 3h

Better than A or B 2 None very clear 1

133
SLIPPERY FALL

A- 21 A-45

No reason 15

A is best ' (others OK) 2 Yellow signifies caution 2 Others OK 1 Tilted boot and skid marks 1

B-84

No reason 20

More eye catching 11

Shows action and consequences 11

More \anders tandable , clear 11

Shows slip hazard 8

(Bigger) , picture of feet 13

slipping

Better looking, more detail 3

All are good 2

Be more careful 1 Use yellow background 1

C-117

No reason 35

Shows person falling, 33

consequences

Most understandable-clearest 11

Color and shape 9

Better drawn, more detail 5

Standard symbol 4

Others could mean trip 2 Full body shown 6

Best 9

Don't like any 1 A and B look like shoe store ads 1

Be careful in this area 1

No reason 22

Shows hole, tripping hazard 15

More understandable 3 Combine A & C, could be better 1 B and C could mean slips , or 3

other things

Color and details 1

B-112

No reason 42

Triangle and color 18

Shows person falling 20

Clearer, better, more under- 23

standable

Combines tripping and falling 4

Need something else 2 Need object by feet 1 No real color 1 Standard symbol 1

C-56

No reason 20

Clearly shows falling 15

Clearest, better 14

Shows high place, elevation 2 Shows severity of hazard 2 Shows open area 1 Shows tripping 1 None real good 1

134
FORK LIFT TRUCK

A- 13

No reason 58

Clearer, easiest to visualize 20

roost understandable

Looks more like a forklift 7

Person driving forklife 11

Shows forklift in use 5 Shape and color lh

Better than C or B 14

Shows two types of forklifts 1 A and C both good 2^5 Standard symbol, highway sign 3 Shows more hazard, caution 2 All good 1

As long as you know what you are looking at

B-69

No reason 27

Red signifies danger 18

Best, clearest, more informative 11

Shows hazard most clearly 4

Human involvement 4

Shows more than 1 type of forklift 3

No foot traffic 1

Looks like it 1

C-18^

No reason 7

Simple, easy to understand 4

Shape and color 2h

All good 4

Clear of forklift 1

OVERHEAD HAZARD

A-l

Simple and can be used 1 internationally

B-154^

No reason 54

Clearest, easiest to understand 20

Depicts hazard better 35

Shows overhead object, need to 37^

look up

Color and shape 5 Broken cable 2 Standard symbol 1 It is in the middle 1

C-66^

No reason 32

More understandable 7 Consequences clear 8

Shows object falling on person 9

Hard hats also needed 4

Better than A or B 4

Needs to be yellow 1 Careful where you walk 1 Depends on overhead hazard \

135
POISON ENTANGLEMENT

A- 10

More easily recognized by kids 5 Tongue more defined 1

New s ign 1

Bad 1

No reason 2

B-136

No reason 77

Symbol widely known and 54

recognized

Best, most easily understood, 23

more impact

Idea of death, danger, skelaton 28

Shows poison 18

A not clearly a hazard 9

Neither 2 Combine both 1

A-25*5

No reason 10*2 Indicates opening gearing, 5 machinery area Broader meaning - no injury shown 1

Red 4

Clearer 3 Should have hand in gear 1 Still isn't clear 1

B-10

No reason 6

Shape and color 2 Just like it 1 Don ' t like any 1

C- 184*5

No reason 61*5 Shows consequences, hand in gears 74

Looks painful, dangerous 15

Easy to visualize, clear 24

A and B are confusing 4 Neither is particularly clear 1 Color should be red 2 Best size 1 Could be drawn better 2

136
GENERAL WARNING

A- 89

No reason 39

Neither is good 19

Exclamation point shows urgency 7

gets attention

Indicates caution 7

Needs better symbol, unfamiliar 4

Best, easily understood 8

B looks like crossing 2 Symbol shows generalities 1

Good use of visual aids 1

This symbol with caution written 1

would be good

B-66

No reason 31

Both are bad 10

X indicates not to do something, 6

danger, stop

X more familiar 2 More understandable, graphic 6

A doesn't imply warning, looks 3

like exclamation point

Better of 2 bad signs 4

Vague, confusing 2

Covers everything 1

If that was the code 1

137
NO OPEN FLAME NO SMOKING

A- 9 Ah

No reason 35

Excludes all flame, not just 25

matches

Clearer, easier to see 7 Less confusing, best, easier to 7

understand

Depicts flame better 10

Others look like cigarette, could 4

mean no smoking

A and B together would be better 2h. Could be better illustrated 1

None are good 2 B could be used 1

B-101%

No reason 41

More graphic visible 15

Shows "no open flame" better 13

Shows matches , beware 12

Easiest to understand 10

Have seen before 3

Could also mean no smoking 3

All good 3h

Don't like A or C 1

C-19

No reason 8

Match clearer 4

Best, easiest to understand 5 A is poor 1 Match is out 1

A- 78

No reason 43

Cigarette most realistic 10

Best, better graphics 15

Attracts eye, preferrable 3 Circle, slash 2 Bigger picture 1 Why not 1

Both OK 1

B could resemble a building 1 Both could be improved 1

B-123

No reason 57

Better graphic, more visible, 30

clearer

Looks more like cigarette 10

Better, easiest to understand 4

Black on white background 6

I've seen it 4

Both good 6

Horizontal representation easiest 1 to read

Should be everywhere 1 Looks like cigar 1 Line doesn't cross smoke 1 Why not 1

First one I've seen 1

138
EYEWASH SAFETY SHOWER

A- 69^ A3

No reason 21 No reason 1 Shows basin, real equipment 15 Good, but lacks person 1 Best, self-explanatory 10 Clarity 1

Shows person washing eye 12

Could be drawn better-head, eye 5

None good 3

Don't take chances 1 Shows head 1

B-72 B-186

No reason 33 No reason 74

Clearer, more descriptive 7 Person actually using shower 24

Easier to understand 4 Person in shower (with clothes) 13

Better symbol 8 More information, more detail 31

Shows eye and water 12h Clear, best, most understandable 22

All are poor 4 Shower clear 13

More human 1 Relates better to safety 4

Could be improved 1 C could be a light 2 All are good h C also good 1 Not all eyewash equipment looks l Used in plant 1 like this A and B don't look like shower 1

C-68% C-33

No reason 30 No reason 20

Clearer, more understandable 13 Clearer - more understandable 8

Eye and fountain clearest nh Graphic, good contrast, more 4

Better (eye) 10 visible

Color 1 Concise 1 Looks like a torch 1

Universal sign 1

Combine A and C 1

139
A-131

FIRST AID

No reason 58

Standard sign 40

Red cross sign, medical 12

assistance

Best, easily understood 11

Looks good, most visible 4

Should be red 2 Both poor 1

More specific 1

Don't like hand, fingers in B 1

Both good 1

B-88

No reason 34

Shows (completed) first aid 24

Shows hurt hand, minor injury 10

Shows A plus more 6

Best, better understood 10

A would be red cross to color 1

blind

A looks like safety symbol 1 Didn't understand A 1

Both OK 1

140
EAR PROTECTION REQUIRED

A-146

No reason 58

Shows gear on, being put on, 40

person

Better, more detailed 16

Easiest to understand 20

Draws attention to ear 3

Shows protection clearly 3

All are good 3

Like cartoon man 1

B looks like tunnel - not good 2

B-38

No reason 19

Simple, most visible 9

Descriptive, understandable 5

Most frequently seen n 1

Symbol alone 3

Person with muffs 1

C-37

No reason 18

Simpler, clearer picture 7

Man with ear protection 4

Shows ear muffs 2

Best, easier to understand 4

Should be in yellow triangle 1

Hands in "A" covers ear protection 1

FOOT PROTECTION REQUIRED

A-32

No reason 19

Best easiest to understand 4

Shows hard toe 3

Looks like safety shoe 3

Two shoes more explanatory 1

All good 1

None good 1

B-50

No reason 25

Simpler easier to read 14

Best, easily understood 4

Boot stands out 3 Shows hard toe 2 Need yellow and black triangle 1 Need better sign for shoe 1

C-135

No reason 57

Action of putting boot on 35

Boot and person 7 Best, most meaningful 26

Safety boot needed 3 Rest poor, look like shoe store 3

ads

All are good 2 All are poor 1

Eye catching 1

141
HAND PROTECTION HEAD PROTECTION

A-177 A- 6 5*2

No reason 70 No reason 21

Shows action , person and gloves 68 Shows putting hat on 16*2 Better, clearer, easier to 30 Best most understandable 9

unders tand More graphic, detailed, easy to 12

All are good 3 see Shows need for hand protection 3 Modern hard hat 4

Looks more like gloves 1 Define hat better 1 A and C about same, show 2 hands 1 Would like to see triangle 1 Selection needs to be better 1 In our plant 1

B-26 B-52

No reason 10 No reason 28

Simple, clear, sufficient 9 Shows hat on person 14

Easily understood 5 Shows hat, what to wear 2*2 All good 1 Simple, easiest to recognize 5 Covers more of hand 1 Best 2 More widely used *2

C-14 C-103*2

No reason 6 No reason 34

Shows two hands 4*3 Best, most recognizable 16

B might mean halt 1 Most plain, clear, visible 19

Best 1 Hat, what's needed 18

All good 1 Most direct version of message. 6

A and C about same *2 face and hands clutter

Familiar 5 A and B poor 2 Would be better if yellow 1*2 Should be in Triangle 1 Would be good standard sign 1

142
EYE PROTECTION REQUIRED RESPIRATOR REQUIRED

A- 2 3%

No reason 12

Glasses alone significant 3

Clear, simplest 4%

More distinctive, visible 3

B and C could have other meanings 1

B-85

No reason 35

Shows person wearing glasses 28

Indicates eye protection must be 6

worn

More meaningful, understandable 11

Standard symbol 1

More for our type work 1

Simpler, clear, better 3

C-112%

No reason 49

Safety goggles imply eye 14

protection

Looks more like safety equipment 9

Shows possible debris 1

Clearer, more understandable 11%

In colors of hazard, caution signs 10

Would prefer triangle 1

Best of three 10

Most common 5

All good 1

Could be better 1

A- 137*2

No reason 56%

Clearer, easier to understand 18

Person and mask 17

Head more pronounced 5 Detail of mask 18

Best 14

More familiar 3 B and C imply eye coverage, scuba 2 gear

B - bad 1 No smoking 1 All choices good 2

B-20%

No reason 6%

Looks more like respirator 8

Eye catching, best graphics 2 Says caution with yellow 2 background 2 Needs human figure 1 Used in our plant 1

C-61

No reason 26

More easily understood 10

Good mask 1

3

Simple and basic 4

Face and mask, better 3 Can be seen further away 1 Looks like spaceman, could be 2 better

B not bad 1 Most familiar 1

143
USE ELEVATOR IN CASE OF FIRE

A- 4 8

No reason 19

More understandable 12

Clear, easier to spot at a glance 8

Shows person using stairs 2 More familiar 2 Steps and flame 3

Best choice, but does not say "do 1

not use elevator"

Fire is to close in B 1

B-170

A looks like fire exit 1

No reason 54

Indicates do not use elevator 37

More meaningful 26

Shows both meanings 19

Better 14

A could mean don't use stairs 2 Clearer, more detailed 6

Shows man on stairs 3

Could be clearer 2 Marking on door 1

Both poor 1

Could mean any type of emergency 1

Red stands out, refers to fire 1

Redo colors 1

A not bad 1

FIRE ALARM

A- 2 8

No reason 11

Shows bell 8

Better than others 2 More understandable 1 Don’t like any 5 Fire truck 1

B-104

No reason 24

More understandable as alarm 40

Better than others 11

Hammer and bell, sound 9

Not easily recognized 6

Best of a bad lot 3 Others are for fire 1 Indicates call in location 2 None 3 Clearer 2 C looks like FD telephone 2 A and B are good 1

C-76

No reason 23

Shows fire , phone 16

Indicates warning alarm location 12

Clear, more visible 6

Most understandable, better 6

None really good 4

International sign 1 A and B look like hearing danger 2 Unclear 2 Need alarm instead of phone 1 Needs to be more explanatory 1 Should be in a triangle 1 Only if fire phone present 1

144
EMERGENCY EXIT GENERAL EXIT

A- 118

No reason 47%

Shows bot±i emergency & egress 14

Better characterized 19

Red implies urgency , emergency 15

exit

Shows more of a danger situation 4%

More meaningful 11

Shows door 1

All good 1

Person escaping 5

B-48

No reason 22

Green shows go, safety 11

Others restricted to fire exit 5

Man running out door 3

Best, illustrative 4

Colors could be better 2 All are good 1

C-53

No reason 27%

Shows emergency and Direction 14%

Simple easily understood ^ Like different colors, stand out 3

Others imply panic 1

Need something else 2 A good 1

A-28%

No reason 15

Arrow points opening 6

Easier to understand 2%

Shows you where you are 1

Don1 t really like any 1 Poor sign 1 Others vague 1 Resembles E for exit 1

B-5

No reason 2 Reverse of no entry 1 International usage 1 All choices poor 1

C-173%

No reason 48

Shows figure and direction 31

Shows door way out 31

Better, others confusing 26

More meaningful 19%

All bad 14

Prefer words 3 More detailed than A 1

145
NBS-H4A (REV. 2-8C) U.S. DEPT. OF COMM. 1 BIBLIOGRAPHIC DATA

PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3.

SHEET (See instructions)

4. TITLE AND SUBTITLE

NBSIR 82-2485

Publ ication Date

June 1982

Symbols for Industrial Safety

5. AUTHOR(S)

Collins, Belinda L; Lerner, Neil D. ; Pieman, Brian C.

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions) 7. Contract/Grant No. NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

8.

Type of Report & Period Covered

Final

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS ( Street. City. State, ZIP)

National Institute of Occupational Safety & Health

944 Chestnut Ridge Road

Morgantown, West Virginia 26505

10.

SUPPLEMENTARY NOTES

J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT ( A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

Written signs are commonly used in industrial sites to provide hazard warnings and

safety information. The use of safety symbols may increase the effectiveness of

safety communication, because such signs are language-free, and because they can be

| recognized more rapidly and accurately than written text even under some conditions

of interference and distraction. The effectiveness of safety symbols critically

depends upon the selection of symbolic images which are readily understandable to the

intended audience. A four phase evaluation of a set of selected industrial worksite

symbols is described. The four phases involved identification of 33 key safety

messages, selection of candidate symbols for each message, evaluation of the understandability of the candidate symbols, and determination of the preference for the 87

candidate images, using both industrial and nonindustrial (naive) personnel. Symbol

understandability , in terns of percentage of correct responses and confusions, varied

widely for the thirty-three referents. Despite standardized use for a number of years

the radiation, biohazard, and laser symbols were frequently misidentif ied. Symbols

for protective gear, first aid, and emergency equipment were generally correctly

identified. The different images selected for various hazards show the greatest range

in understandability, with the results for symbolic versions of entanglement,

electricity, corrosion, and overhead hazard being quite different. The most frequent!

correct image was usually also the most preferred.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) communication; hazard; pictogram; safety; signs; standards; symbols; visual alerting;

warnings

13. AVAILABILITY 14. NO. OF

PRINTED PAGES ' XjXX| Unl imited

ITT! For Official Distribution. Do Not Release to NTIS 157

IT”] Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402. 15. Price i

j^^Order From National Technical Information Service (NTIS), Springfield, VA. 22161 $15 .00

USCOMM-DC 6O43-P80
V