Trust and Acceptance of Risks
Satoshi Fujiia, Toshiko Kikkawab and Kazuhisa TakemuracaTokyo Institute of Technology,
2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552, Japanb

Keio University,
2-15-45, Mita, Minato-ku, Tokyo 108−8345, Japanc

Waseda University,
1−24−1, Toyama, Shinjyuku-ku, Tokyo 162−8644, Japan

This study sought to understand the determinants of risk acceptance. Thus, we
implemented a survey (n = 200) to ask participants which policy measures would makeapprove each of the following risks: nuclear power plants, traffic accidents, food safety,
electrical appliances, and medical mishaps. These results indicate that risk acceptancecannot be fully explained only by objectively achieved security, but other factors, such as
scientific understanding and trust in workers and organizations, were also found to beimportant for increasing risk acceptance.

1. Introduction
Daily life incurs many risks. For example, a large earthquake may strike Japan in the next
twenty to thirty years, traffic accidents occur daily, and human error has led to nuclear
power plant disasters, such as at TMI or Chernobyl; furthermore, no one knows when thenext infectious disease, such as SARS, will emerge. Unfortunately, few Japanese have theoption of living in a place without earthquakes; we cannot drive a car without traffic
accident risks, and our energy-consuming lifestyles lead us to rely on nuclear power plants.
Even eating the food we need to survive incurs the slight risk of food poisoning. We cannever truly free ourselves from risk.
There is a growing concern with risk and safety in Japan. This concern has been
attributed to an increase in technological accidents that have occurred in recent years, aswell as to scientific uncertainty over the probability of risks. While we must assiduously
work to reduce technological risks, we still have to accept these risks, to some extent,
because it is impossible to eliminate such risks completely.
Therefore, the practical problem with which this research was concerned was tounderstand how people accept risks, given the impossibility of achieving zero-risk status.

To examine determinants of risk acceptance for several risk events, we surveyed 200 Tokyo
residents to find their response to a variety of risks.

2. Risk Acceptance
When do people accept risks? Researchers have investigated this question for decades[1]. The simplest answer is that people do not accept risks and, instead, work to eliminate
risk. If all risks are eliminated, security is guaranteed and a zero-risk state is achieved.
Although risk-reduction efforts are necessary, society will always face some risks.
Achieving zero-risk status might not be a realistic aim to strive for.
Another answer is that people rationally accept risks if they expect the expected benefitof an activity to exceed the expected cost [2]. For example, people may drive a car,knowing the risk of a traffic accident, if they believe that car use is beneficial. People may
also accept nuclear plants, as long as the energy produced improves the quality of theirlives.
However, many empirical studies (c.f. [3] [4] [5] [6]) have contradicted the above claims.
These studies have found that personal decision making frequently deviates from theoriessuch as the “expected utility theory,” [7] or the “subjective expected utility theory,” [8],which assume rational, decision making based on cost and benefit. Cost and benefit
expectations can be important determinants of risk acceptance, but they do not fully explain
the process. No one yet knows the probabilistic distribution of some risks, such as
endocrine-disrupting chemicals. Other risks, such as risks from electromagnetic fields,
remain controversial. We cannot evaluate these risks by science, or by costs and benefits,alone.
We compared the relative weight of two components of risk: the possibility of risk andthe damage from risk. These two possible determinants are closely related to cost
expectation, which is assumed to determine decision making in rational choice models,such as the expected utility theory. We also investigated the effects of compensation afterrisk events have occurred. Compensation is expected to reduce or to eliminate the cost ofrisks. Additionally, we examined how understanding the scientific causes of a risk affectedrisk acceptance. Scientific understanding may reduce the extent of unknown risks [2] andmay lead to risk acceptance.

3. Trust and Risk Acceptance
We presumed that trust in workers and regulatory agencies constitutes another important
determinant of risk acceptance. Instead of controlling risks by themselves, individuals maytrust in, and delegate power to, organizations or institutions. This situation can berepresented through the “Trust Game” [9].

Player A
trust

not trustPlayer A’s income = 0
Player B’s income = 0
total income = 0

Player B
betrayPlayer A’s income = - X
Player B’s income = 2X
total income = X

reciprocate(repaying trust)Player A’s income = 0.5X
Player B’s income = 0.5X
total income = X

Figure 1. An example of the Trust GameThe Trust Game has two players: Player A (the truster) and Player B (the trusted). Player
A can “trust” Player B by sending a monetary endowment X (see Fig. 1). Player B thenreceives double what player A has sent (i.e., 2X). Player B must choose between“reciprocating” (returning 1.5X and taking 0.5X for himself) and “betrayal” (taking all hehas received, i.e., -2X). In this game, if Player A trusts Player B, the total monetary amountthat Player A and Player B have increases by X. However, if Player A does not trust Player
B, there is no collective increase. In this situation, trusting behavior is collectively
beneficial. However, if Player B betrays Player A, Player A loses X. If Player A fears thisrisk, he does not trust Player B, which results in no collective benefit.
The basic structure underlying risk problems in our society may be seen as resemblingthat of the Trust Game, assuming that lay people represent Player A and risk experts
represent Player B. Social benefits may increase if lay people “trust” risk experts by asking
them to administer risks. Risk experts may “reciprocate” by successfully managing the risk,or “betray” by failing to effectively manage risks. If people expect experts to reciprocate,trust and social benefits may increase. However, if people expect betrayal by the experts,
trust and social benefits may not increase. For example, social benefits could increase if
electricity companies repay the trust of the public by managing nuclear plants successfully.
Social benefits would not increase if nuclear plants ceased operations due to a lack ofpublic trust. If electricity companies fail in repaying public trust due to a serious nuclear
plant problem, social benefits will decrease.

4. Methods
4.1. Sample
Tokyo residents living within 50 km of the city center were randomly selected as
participants for the August 2002 survey. A surveyor first visited the residents to ask them ifthey would participate in the survey. If the resident agreed to participate, a questionnairewas left at the home. After a few days, the surveyor again visited the home and collected thequestionnaire.

4.2 Measures
As discussed above, we assumed that risk acceptance is determined by factors beyond
subjective expectations of costs and benefits. We assumed that trust in persons andregulatory agencies in charge of risk would be another important determinant. Thus, we
asked respondents to evaluate political policies or decisions implemented by administratorsand the government. In the questionnaire, we asked respondents to consider six risk
management measures and to choose three out of the six measures that would increase theirrisk acceptance for each of the following risks: nuclear power plants, traffic accidents, foodsafety, electrical appliances, and medical mishaps. The six choices were:
(1)
(2)
(3)
(4)
(5)
(6)

Decrease the probability that the risk occurs.
Minimize the damage when the risk occurs.
Compensate for damages when the risk occurs.
Know that the government adequately manages the risk.
Know that workers and regulatory agencies are trustworthy.
Know that scientific mechanisms of accidents and mishaps are well understood.

These six measures correspond to determinants of risk acceptance, as discussed in thefirst section. In the questionnaire, the following phrasing framed the question related toeach risk:
With respect to (type of risk inserted here), how do you achieve a feeling of “an-shin”?
Of the following six statements, which do you consider the first-, second-, and third-mostimportant factors in creating a sense of “an-shin”?
An-shin in Japanese corresponds to “security” in English, but connotes, additionally,peace of mind. People may lack an-shin even when they are guaranteed security. People
may have peace of mind, even when they are not guaranteed security from risks.
To ask participants directly whether they would be willing to accept certain risk eventsmight not be appropriate, as almost all risks in our society exist as if they have already beenaccepted. Therefore, we measured an-shin instead of directly asking about risk acceptance.
Note, that in the next section, we use the term “risk approval” for this measure of an-shin.

5. ResultsTable 1 Distributions and means of ranks of the six policy actions according to perceived
effectiveness to increase risk approval.

1st
2nd
decrease the
3rdprobability that>=4th
the risk occurs.
mean rank
1st
2nd
minimize the
3rddamage when>=4th
the risk occurs.
mean rank
1stcompensate for2nd
the damages
3rd
when the risk>=4th
occurs.
mean rank
1stknow that the
2nd
government
3rd
adequately>=4th
manage themean rank
risk.
1st
2nd
3rd>=4thknow thatworkers andregulatory
agencies aretrustworthy. mean rank
know that
1stscientific
2ndmechanisms of
3rd
accidents and>=4th
mishaps aremean rank
wellunderstood

medicalmishaps
freq.
％
46
23.0
49
24.5
44
22.0
61
30.5
2.91**
23
11.5
37
18.5
48
24.0
92
46.0
3.51*
6
3.0
18
9.0
37
18.5
139
69.5

freq.
％
55
27.5
43
21.5
39
19.5
63
31.5
2.87**
19
9.5
45
22.5
31
15.5
105
52.5
3.64
3
1.5
10
5.0
39
19.5
148
74.0

electric
appliance
freq.
％
51
25.5
55
27.5
43
21.5
51
25.5
2.73***
36
18.0
49
24.5
47
23.5
68
34.0
3.08*84.0
28
14.0
40
20.0
124
62.0

4.24

4.40

4.02

7
17
18
158

3.5
8.5
9.0
79.0
49.5
22.5
11.5
16.5

2.12***
19
34
30
117
3.81

38
28
23
111

19.0
14.0
11.5
55.5

11
88
173

37.0
23.5
15.0
24.5

30
30
26
114

3.59*

4.43
99
45
23
33

food

9.5
17.0
15.0
58.5

74
47
30
49

3.69

11
27
38
124

64
30
36
70

4.00

5.5
13.5
19.0
62.0

2.91**

4.59

3.65*

5.5
4.0
4.0
86.5

40
21
28
111

15.0
15.0
13.0
57.0

38
34
20
108

20.0
10.5
14.0
55.5

18
1321148

19.0
17.0
10.0
54.0

20
19
26
135

3.61

4.58

2.52***

freq.
％
49
24.5
24
12.0
48
24.0
79
39.5
3.18**
42
21.0
57
28.5
40
20.0
61
30.5
2.91***
1
0.5
10
5.0
24
12.0
165
82.5

traffic
accidents
freq.
％
103
51.5
45
22.5
29
14.5
23
11.5
1.98***
31
15.5
79
39.5
30
15.0
60
30.0
2.90**
15
7.5
26
13.0
66
33.0
93
46.5

nuclear plants

4.24

3.53
32.0
15.0
18.0
35.0

30
54
40
76
3.19*

9.0
6.5
10.5
74.0
10.0
9.5
13.0
67.5

4.06
15.027.0
20.0
38.0

131828141

6.5
9.0
14.0
70.5

4.19

Note: For calculating mean ranks, ranks for options that were not selected as top three options were assumed
as “5.5” that is mean ranks between 4th and 7th.
***
the highest-ranked policy, ** the second-highest-ranked policy, * the third-highest-ranked policy

Table 1 shows the distributions and mean ranks of the six risk management measures,
according to perceived effectiveness with regard to increased risk approval. The tableshows that measures to decrease the probability of risk occurrence and measures tominimize damages from risk were evaluated as effective in increasing risk approval for therisks listed in the questionnaire. The former was the most effective in increasing risk
approval for electrical appliance and traffic accidents, while the latter was the mosteffective in increasing risk approval for nuclear plants.
Respondents indicated that measures that decrease the expected cost of the risks (that is,measures minimizing the damage and probability of the risks) were also effective for
medical mishaps and food risks. However, increasing trust in workers and regulatory
agencies was evaluated as more effective than decreasing expected costs. Thus, increasing
trust is the most effective risk management measure with regard to food risks and medical
mishaps. Regarding electrical appliance and nuclear power plant risks, respondents chosescientific understanding and explanation of accident mechanisms. These two risks differ
from the other risks, such as traffic accidents, food, and medical mishaps, in that they arecaused by more advanced technologies, which are less likely to be understood, even by risk
experts.
Compensation for risk damages was not chosen as effective in increasing risk approval,
except for the traffic accident risk. Respondents indicated that risk approval for trafficaccidents may increase with the compensation measure. This may be because damage fromtraffic accidents is generally less than damage from the other risks presented in thequestionnaire. Additionally, it is likely that many people will actually face traffic accidents
in their lives.

6. Discussion
This study sought to understand the determinants of risk acceptance. Thus, surveyparticipants were asked which policy measures would make them feel “an-shin”, as anindicator of risk approval. The results showed that the risk management measures thatwould increase risk approval depended on the respective risks. The following threefindings emerged from the survey.
1) For traffic accidents, nuclear power plants, and electrical appliance risks, the mosteffective measure for risk approval was that of minimizing the damage or theprobability of accidents.
2) For food and medical mishap risks, the most effective policy was that of increasingtrust in workers and regulatory agencies, rather than that of minimizing the damage
or the probability of accidents.
3) Risk approval for electrical appliances and nuclear power plants could increase if
people knew that the scientific mechanisms of accidents and mishaps were wellunderstood.
A possible reason why trust in workers and organizations is so important for food andmedical mishap risks is that medical and food workers, and their organizations, areassumed to have relatively more control over these risks, unlike the other risks presented
here. Electrical appliance and nuclear accidents, on the other hand, are assumed to stem
more from mechanical error than from human error. This explanation also agrees with thefinding that better understanding of scientific mechanisms is important for electricalappliance and nuclear plants risks. Conversely, the mechanisms of food and medical
mishaps may be simpler than problems associated with nuclear power and electricalappliances. Thus, people may believe that increasing accident prevention among workers
and organizations is most effective in this case. Traffic accidents were assumed to be lessunder the control of workers and organizations (such as the police in charge of traffic) thanaccidents from medical mishaps and foods. We believe this is why trust was not considered
as an important determinant for traffic accident risk approval.
These results indicate that risk acceptance cannot be fully understood by adopting arational choice theory, which assumes that people maximize the expected benefits and/orminimize the expected costs. Minimizing damage and the probability of accidents wereassumed to be just two examples of effective risk management measures for increasing risk
approval or, in more commonly used words, risk acceptance. In other words, the feeling of
an-shin, or risk approval, cannot be explained only by objectively achieved security. Other
factors, such as scientific understanding and trust in workers and organizations, were also
found to be important for increasing risk acceptance.
This indicates that those who wish to increase the public’s risk acceptance should appear
trustworthy and try to understand the scientific mechanisms of accidents; they should also
try to minimize risk damage and probability. Trust is important, especially for risks whereaccidents can be prevented relatively easily by workers and/or organizations. These risks
include those associated with food and medical mishaps. Scientific understanding of riskmechanisms is also important for risk acceptance, especially for risks involving
mechanisms that are relatively complex, such as nuclear power and electrical appliancerisks.

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