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This chapter explores the bases of risk assessment and demonstrates that judgment of risk is fallible. It also shows that the degree of fallibility is often surprisingly great and that faulty estimates may be put forth with much confidence. For almost 40 years, researchers have been using psychometric methods to elicit quantitative measures of perceived risk, perceived benefits, and acceptable levels of risk from a wide variety of activities, technologies, and natural hazards. This "psychometric paradigm" encompasses a theoretical framework that assumes risk is subjectively defined by individuals and may be informed by a wide array of psychological, social, institutional, and cultural factors. There are emerging networks across communities and even larger scales, and, of course, decision and deliberation processes can matter greatly. The field of risk perception and its communication have been continually plagued by two often entirely unmerited assumptions regarding public attitudes to and acceptance of risks.
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Many decision theorists believe that the axioms of rational choice are similar to the principles of logic in the sense that no reasonable person who understands them would wish to violate them. The present study questions this view by investigating the acceptability of a key axiom underlying expected utility theory—Savage's independence principle. Persistent violations of this axiom were observed, even after it was presented to subjects in a clear and, presumably compelling fashion. The problem of distinguishing between rejection of a decision principle and failure to understand it is discussed.
The relation of preference between acts or options is the key element of decision theory that provides the basis for the measurement of utility or value. In axiomatic treatments of decision theory, the concept of preference appears as an abstract relation that is given an empirical interpretation through specific methods of elicitation, such as choice and matching. In choice the decision maker selects an option from an offered set of two or more alternatives. In matching the decision maker is required to set the value of some variable to achieve an equivalence between options (e.g., what chance to win $750 is as attractive as 1 chance in 10 to win $2,500?).
An article of faith among students of value, choice, and attitude judgments is that people have reasonably well-defined opinions regarding the desirability of
Subjects in 3 experiments chose their preferred bet from pairs of bets, and later bid for each bet separately.In each pair, one bet had a higher probability of winnirig.(Pbet); the other offered more to win (S bet).Bidding method (selling vs. buying) and payoff method (realplay vs. hourly wage) were varied.Results showed that when the P bet was chosen, the$ bet o~en received a higher bid.These inconsistencies violate every risky decision model, but can be understood via informationprocessing considerations.In bidding, S starts with amount to win and adjusts it downward to account for other attributes of the bet.In choosing, there is no natural starting point.Thus amount to win dominates , bids but not choices.One need not call this behavior irrational, but it casts doubt on the descriptive validity of expected utility models of risky decision making.
Subjects were asked to estimate the answers to 16 questions concerning uncertain quantities like, “How many people are employed by hospitals in the U.S.?” under five different aiding conditions. The most-aided group (Full Algorithm) was given a complete algorithm and asked to make estimates for all the parts of the algorithm and to combine the parts as indicated to arrive at an estimate of the desired quantity. The second group (Partial Algorithm) was given the same algorithm without indications of how to combine the parts. After making estimates of the parts, these subjects then estimated the desired quantity. The third group (List & Estimate) was asked to list components or factors they thought were relevant, make an estimate of each item on their list, and then estimate the desired quantity. The fourth group (List) was asked to make such a list, but they were not asked to make estimates of each item before making an estimate of the desired quantity. The fifth group received no aid. The results generally showed improved performance in terms of both accuracy and consistency across subjects with increasing structure of the aid. Generalization of these results to practical estimation situations is possible but limited by the need, in real situations, for the estimator to develop the algorithm, a task that was done here by the experimenters.
Empathic responses, such as sympathy towards others, are a key ingredient in the decision to provide help to those in need. The determinants of empathic responses are usually thought to be the vividness, similarity, and proximity of the victim. However, recent research highlights the role that attention plays in the generation of feelings. We expanded on this idea by investigating whether sympathy depends on cognitive mechanisms such as attention. In two studies we found that sympathy responses were lower and reaction times were longer when targets were presented with distractors. In addition, online sympathy judgments that allow attentional focusing on a target lead to greater affective responses than judgments made from memory. We conclude that attention is an ingredient in the generation of sympathy, and discuss implications for research on prosocial behaviour and the interaction between attention and emotions.
The present report describes an expanded replication of the previous experiments in a nonlaboratory real-play setting unique to the experimental literature on decision processes - a casino in downtown Las Vegas.
1 Members of the British Toxicology Society partici pated in a survey to determine their attitudes, beliefs, and perceptions regarding risks from chemicals. Similar surveys had previously been conducted with toxicologists and members of the general public in the United States and Canada. Data from 312 completed questionnaires were analyzed. 2 In general, the British toxicologists judged risks to be quite low for most hazards, with the exception of cigarette smoking and asbestos. They tended to have quite favorable attitudes toward the use of chemicals and were confident about the adequacy of chemical regulations. 3 As in previous studies of toxicologists, women expressed higher perceptions of risk than did men and had consistently stronger anti-chemical attitudes. 4 Toxicologists working in industry had more favorable attitudes towards chemicals and their use than did those working in academic settings. 5 When asked to evaluate technical summaries of various animal studies there was considerable dis agreement among the respondents about the toxicity of the chemicals involved. 6 In general, British toxicologists were equivocal about the reliability of animal studies in predicting human effects (particularly carcinogenicity) probably be cause of the belief that animal studies overestimate risk. However, they were rather confident that human health risks could be assessed reasonably accurately.
Understanding those factors critical to predicting public response is crucial to our ability to model the consequences of a terrorist strike in an urban area. Sixteen hypothetical damage scenarios were systematically varied according to non-terrorism vs. terrorism, explosions vs. infectious disease releases, terrorists' motives as demands to release prisoners vs. solely to instill fear, non-terrorists' motives as non-intentional vs. intentional (criminal), victims as government officials vs. tourists, non-terrorist incidents as involving no negligence vs. negligence, terrorist acts as non-suicidal vs. suicidal, and number of casualties (0, 15, 495). The setting was a local theme park. Students at a university in San Diego County were randomly assigned to different scenario conditions. For these scenarios, they were asked to address a number of questions regarding their perceptions and likely behaviors during and following an accident or terrorist strike. Results from regression modeling and Multivariate Analysis of Variance (MANOVA) indicated that terrorism and the mechanism used were most influential followed by the presence of suicide or negligence, motive, and victim. Number of casualties made little difference once these other factors were accounted for. To forecast community response, a system dynamics model was introduced that incorporated the study's survey findings. This model simulated the immediate and mid-term diffusion of fear in a community for different types of accidental and terrorist events. These findings should prove useful to those wishing to predict public response to a variety of different contingencies involving terrorism.
Contingent valuation (CV) has been used by economists to value public goods for about 25 years. The approach posits a hypothetical market for an unpriced good and asks individuals to state the dollar value they place on a proposed change in its quantity, quality, or access. Development of the CV concept has been described in reviews by Cummings, Brookshire, and Schulze (1986) and Mitchell and Carson (1989). The approach is now widely used to value many different goods whose quantity or quality might be affected by the decisions of a public agency or private developer. Environmental goods have received particular attention, because they are highly valued by society and entail controversial tradeoffs (e.g., manufacturing costs vs. pollution, urban development vs. wetlands protection) but are not usually sold through markets (Bromley, 1986).
In a bold and insightful speech before the National Academy of Sciences at the beginning of his second term as the administrator of the Environmental Protection Agency (EPA), William Ruckelshaus called for a governmentwide process for managing risks that involved the public. Arguing that the government must accommodate the will of the people, he quoted Thomas Jefferson's famous dictum to the effect that "if we think [the people] not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion" (Ruckelshaus 1983, p. 1028). Midway into his tenure as the EPA administrator, Ruckelshaus's experiences in attempting to implement Jefferson's philosophy led him to a more sober evaluation: "Easy for him to say. As we have seen, informing discretion about risk has itself a high risk of failure" (Ruckelshaus, 1984, p. 160). This chapter attempts to illustrate why the goal of informing the public about risk issues—which in principle seems easy to attain—is surprisingly difficult to accomplish. To be effective, risk communicators must recognize and overcome a number of obstacles that have their roots in the limitations of scientific risk assessment and the idiosyncrasies of the human mind. Doing an adequate job of communicating means finding comprehensible ways of presenting complex technical material that is clouded by uncertainty and inherently difficult to understand. Greater awareness of the nature of risk perceptions, the fundamental values and concerns that underlie those perceptions, and the difficulties of communicating about risk should enhance the chances of designing an environment in which all parties can cooperate in solving the common problems of risk management. Risk assessment is a complex discipline, not fully understood by its practitioners, much less by the lay public. At the technical level, there is still much debate over terminology and techniques, and technical limitations and disagreements among experts inevitably affect communication in the adversarial climate that surrounds many risk issues. Those conveying these issues to the public must be aware of the strengths and limits of the methods they use to generate this information. In particular, such risk communicators need to understand that risk assessments are constructed from theoretical models that are based on assumptions and subjective judgments.
