Paul Slovic

Heuristics and Biases: The Affect Heuristic

Abstract This paper introduces a theoretical framework that describes the importance of affect in guiding judgments and decisions. As used here, “affect” means the specific quality of “goodness” or “badness” (i) experienced as a feeling state (with or without consciousness) and (ii) demarcating a positive or negative quality of a stimulus. Affective responses occur rapidly and automatically—note how quickly you sense the feelings associated with the stimulus word “treasure” or the word “hate”. We argue that reliance on such feelings can be characterized as “the affect heuristic”. In this paper we trace the development of the affect heuristic across a variety of research paths followed by ourselves and many others. We also discuss some of the important practical implications resulting from ways that this heuristic impacts our daily lives.

Decision Making: KNOWING WHAT YOU WANT: MEASURING LABILE VALUES

An article of faith among students of value, choice, and attitude judgments is that people have reasonably well-defined opinions regarding the desirability of various events. Although these opinions may not be intuitively formulated in numerical (or even verbal) form, careful questioning can elicit judgments representing peoples underlying values. From this stance, elicitation procedures are neutral tools, bias-free channels that translate subjective feelings into scientifically usable expressions. They impose no views on respondents beyond focusing attention on those value issues of interest to the investigator. What happens, however, in cases where people do not know, or have difficulty appraising, what they want? Under such circumstances, elicitation procedures may become major forces in shaping the values expressed, or apparently expressed, in the judgments they require. They can induce random error (by confusing the respondent), systematic error (by hinting at what the “correct” response is), or unduly extreme judgments (by suggesting clarity and coherence of opinion that are not warranted). In such cases, the method becomes the message. If elicited values are used as guides for future behavior, they may lead to decisions not in the decision makers best interest, to action when caution is desirable (or the opposite), or to the obfuscation of poorly formulated views needing careful development and clarification. The topic of this chapter is the confrontation between those who hold (possibly inchoate) values and those who elicit values.

Heuristics and Biases: Compatibility Effects in Judgment and Choice

One of the main ideas that has emerged from behavioral decision research is a constructive conception of judgment and choice. According to this view, preferences and beliefs are actually constructed – not merely revealed – in the elicitation process. This conception is entailed by findings that normatively equivalent methods of elicitation often give rise to systematically different responses (e.g., Slovic, Fischhoff, & Lichtenstein, 1982; Tversky, Sattath, & Slovic, 1988). To account for these data within a constructive framework, we seek explanatory principles that relate the characteristics of the task to the attributes of the objects under study. One such notion is the compatibility hypothesis, which states that the weight of a stimulus attribute is enhanced by its compatibility with the response. The rationale for this hypothesis is twofold. First, noncompatibility between the input and the output requires additional mental operations, which often increase effort and error and may reduce impact. Second, a response mode may prime or focus attention on the compatible features of the stimulus. Common features, for example, are weighted more heavily in judgments of similarity than in judgments of dissimilarity, whereas distinctive features are weighted more heavily in judgments of dissimilarity (Tversky, 1977). Consequently, entities with many common and many distinctive features (e.g., East and West Germany) are judged as both more similar to each other and as more different from each other than entities with relatively fewer common and fewer distinctive features (e.g., Sri Lanka and Nepal).

Decision Making: RESPONSE MODE, FRAMING, AND INFORMATION-PROCESSING EFFECTS IN RISK ASSESSMENT

The chapter on framing by Tversky and Kahneman (1982) demonstrates that normatively inconsequential changes in the formulation of choice problems significantly affect preferences. These effects are noteworthy because they are sizable (sometimes complete reversals of preference), because they violate important tenets of rationality, and because they influence not only behavior but how the consequences of behavior are experienced. These perturbations are traced (in prospect theory; see Kahneman and Tversky, 1979) to the interaction between the manner in which acts, contingencies, and outcomes are framed in decision problems and general propensities for treating values and uncertainty in nonlinear ways. The present chapter begins by providing additional demonstrations of framing effects. Next, it extends the concept of framing to effects induced by changes of response mode, and it illustrates effects due to the interaction between response mode and information-processing considerations. Two specific response modes are studied in detail: judgments of single objects and choices among two or more options. Judgments are prone to influence by anchoring- and adjustment-processes, which ease the strain of integrating diverse items of information. Choices are prone to context effects that develop as a result of justification processes, through which the deliberations preceding choice are woven into a rationalization of that action. As we shall see, these processes often cause judgments and choices to be inconsistent with one another.

The Construction of Preference: The Construction of Preference: An Overview

This book is a collection of papers and research articles on preference construction. The central idea is that in many situations we do not really know what we prefer; we must construct our preferences as the situation arises. We do, of course, carry a myriad of preferences in our memory. We were born with some of them, such as a fondness for sweets, avoidance of pain, and, perhaps, fear of snakes. Moreover, we spend our lives, particularly in childhood and adolescence, building preferences from our experiences and our wants, needs, and desires. Some of these learned preferences are broad, such as preferring more money to less; others are quite specific, such as liking a particular flavor of ice cream. These well-established preferences are readily available for use. The need for preference construction arises when our known preferences are insufficient to solve the decision problem that we face. It seems to us that these more difficult situations have one or more of the following three characteristics.1 First, some of the decision elements may be totally unfamiliar, such as when choosing what to eat from a menu in a foreign language. Second, the choices available to us may present a conflict among our known preferences, so that tradeoffs must be made. For example, suppose you are choosing between two apartments to rent. One has big windows with a great view but a cramped kitchen. The other has no view but a well-arranged, spacious kitchen. You know you prefer good views and large kitchens, but to make this decision you must make a tradeoff between one aspect (view) and the other (kitchens). Often we know our preferences for individual aspects but do not know the tradeoffs between them. Third, we find it difficult to translate our positive and negative feelings into a numerical response, even when our preferences are clear. For example, suppose you find an apartment with a great view and a big kitchen. Now the question is: How much rent are you willing to pay for this apartment? That question may be hard to answer. Decision researchers rarely study the first problem, unfamiliarity. Indeed, researchers typically take great pains to choose stimuli that are familiar to the study participants. Thus, the emphasis in research on preference construction

Public perceptions of electric power transmission lines

Abstract Electric power transmission lines have recently met a very significant amount of public opposition. The source of such opposition varies from case to case, and is often hard to identify. Stated objections have included land use conflicts, noise created by the lines, aesthetic concerns, and fears of health and safety threats. Despite the sometimes enormous costs and long delays caused by strong opposition to transmission line siting and construction, both utilities and governmental regulators seem baffled at why the public objects so vehemently. At the same time, opponents are often equally baffled at why their objections seem to go unheeded. As a step toward developing satisfactory solutions to the conflict, this article reviews and critiques the literature dealing with attitudes toward electric power transmission lines, and outlines a conceptual framework for understanding the determinants of those attitudes.

Rating the Risks: The Structure Of Expert And Lay Perceptions

People respond to the hazards they perceive. If their perceptions are faulty, efforts at public and environmental protection are likely to be misdirected. In order to improve hazard management, a risk assessment industry has developed over the last decade which combines the efforts of physical, biological, and social scientists in an attempt to identify hazards and measure the frequency and magnitude of their consequences (1).

“The Public” Vs. “The Experts”: Perceived Vs. Actual Disagreements About Risks of Nuclear Power

A recent public opinion survey (Harris, 1980) reported the following three results: n na) n nAmong four “leadership groups” (top corporate executives investors/lenders, Congressional representatives and federal regulators), 94–98% of all respondents agreed with the statement “even in areas in which the actual level of risk may have decreased in the past 20 years, our society is significantly more aware of risk.” n n n n nb) n nBetween 87% and 91% of those four leadership groups felt that “the mood of the country regarding risk” will have a substantial or moderate impact “on investment decisions — that is, the allocation of capital in our society in the decade ahead.” (The remainder believed that it would have a minimal impact, no impact at all, or were not sure.) n n n n nc) n nNo such consensus was found, however, when these groups were asked about the appropriateness of this concern about risk. A majority of the top corporate executives and a plurality of lenders believed that “American society is overly sensitive to risk,” whereas a large majority of Congressional representatives and federal regulators believed that “we are becoming more aware of risk and taking realistic precautions”. A sample of the public endorsed the latter statement over the former by 78% – 15%.

Risk Analysis, Decision Analysis, and the Social Context for Risk Decision Making

The practice of risk analysis has steadily increased in prominence during the past several decades, as risk managers in government and industry seek to develop more effective ways to meet public demands for a safer and healthier environment. Dozens of scientific disciplines have been mobilized to provide technical information about risk, and billions of dollars have been expended to create this information and distill it in the context of risk assessments.

PERCEIVED RISK AND DRIVING BEHAVIOR: LESSONS FOR IMPROVING TRAFFIC SAFETY IN EMERGING MARKET COUNTRIES

Very often the risks of driving are expressed in terms of the total number of deaths that occur yearly as the result of motor vehicle operation. Yet, despite the thousands of people who die each year in automobiles in the U.S. alone, driving behavior seems relatively unresponsive to statistical portrayals of risk. Research in risk perception suggests that this apparent unresponsiveness is rooted in the manner by which risks are psychologically evaluated and judged. In general, perceptions of controllability of a hazard are a prime factor in personal assessments of its riskiness. Unfortunately, drivers appear to have an exaggerated sense of their personal control over driving situations and hazard potential, leaving them unrealistically optimistic about their chances of avoiding harm. However, emerging market countries seeking to develop better motor-vehicle risk management are cautious about drawing too heavily upon risk perception research conducted in industrialized countries with mature risk management institutions - risk as a concept appears highly conditioned on the cultural context within which it is experienced. Thus, emerging nations are encouraged to develop risk management approaches within their own cultural matrix, relying on a base of research stimulated by cross-cultural collaboration.