Sampling experience reverses preferences for ambiguity

People often need to choose between alternatives with known probabilities (risk) and alternatives with unknown probabilities (ambiguity). Such decisions are characterized by attitudes towards ambiguity, which are distinct from risk attitudes. Most studies of ambiguity attitudes have focused on the static case of single choice, where decision makers typically prefer risky over ambiguous prospects. However, in many situations, decision makers may be able to sample outcomes of an ambiguous alternative, allowing for inferences about its probabilities. The current paper finds that such sampling experience reverses the pattern of ambiguity attitude observed in the static case. This effect can only partly be explained by the updating of probabilistic beliefs, suggesting a direct effect of sampling on attitudes toward ambiguity.     

Comparing behavior under risk and under ambiguity in a lifecycle experiment

Experiments on intertemporal consumption typically show that people have difficulties in optimally solving such problems. Previous studies have focused on contexts in which agents are faced with risky future incomes and have to plan over long horizons. We present an experiment comparing decision making under certainty, risk, and ambiguity, over a shorter lifecycle. Results show that behavior in the ambiguity treatment is markedly different than in the risk condition and it is characterized by a significant pattern of under-consumption.     

Learning under compound risk vs. learning under ambiguity – an experiment

We design and conduct an economic experiment to investigate the learning process of agents under compound risk and under ambiguity. We gather data for subjects choosing between lotteries involving risky and ambiguous urns. Agents make decisions in conjunction with a sequence of random draws with replacement, allowing us to estimate the agents’ beliefs at different moments in time. For each type of urn, we estimate a behavioral model for which the standard Bayesian updating model is a particular case. Our findings suggest an important difference in updating behavior between risky and ambiguous environments. Specifically, even after controlling for the initial prior, we find that when learning under ambiguity, subjects significantly overweight the new signal, while when learning under compound risk, subjects are essentially Bayesian.     

Recursive expected utility and the separation of attitudes towards risk and ambiguity: an experimental study

We use the multiple price list method and a recursive expected utility theory of smooth ambiguity to separate out attitude towards risk from that towards ambiguity. Based on this separation, we investigate if there are differences in agent behaviour under uncertainty over gain amounts vis-a-vis uncertainty over loss amounts. On an aggregate level, we find that (i) subjects are risk averse over gains and risk seeking over losses, displaying a “reflection effect” and (ii) they are ambiguity neutral over gains and are mildly ambiguity seeking over losses. Further analysis shows that on an individual level, and with respect to both risky and ambiguous prospects, there is limited incidence of a reflection effect where subjects are risk/ambiguity averse (seeking) in gains and seeking (averse) in losses, though this incidence is higher for ambiguous prospects. A very high proportion of such cases of reflection exhibit risk (ambiguity) aversion in gains and risk (ambiguity) seeking in losses, with the reverse effect being significantly present in the case of risk but almost absent in case of ambiguity. Our results suggest that reflection across gains and losses is not a stable individual characteristic, but depends upon whether the form of uncertainty is precise or ambiguous, since we rarely find an individual who exhibits reflection in both risky and ambiguous prospects. We also find that correlations between attitudes towards risk and ambiguity were domain dependent.      

Communication of ambiguous risk information

This paper reports on the responses of 646 individuals to environmental risk information involving different forms of risk ambiguity. Recipients of more than one set of risk information do not simply average the risk levels provided. Rather, a variety of aspects of the nature of the risks that are communicated influence their probabilistic beliefs. Individuals' perceptions of the risk levels to which they are exposed are likely to be greater: (i) for more ambiguous risks, (ii) for risks for which the unfavorable risk evidence is presented last even when there is no temporal order, (iii) for risks for which the most unfavorable risk studies have been performed most recently, and (iv) for risks where there is asymmetry in the risk ambiguity that imposes substantial potential downside risks. Although these effects are modest for the median individual, the potential for extreme responses that reflect only the most adverse or the most favorable piece of information provided is quite prevalent. These findings are of interest more generally in that they indicate how individuals form their risk perceptions in the presence of risk ambiguity.The authors would like to thank the U.S. Environmental Protection Agency for support of this work under Cooperative Agreements Number CR-815445-01-2 and Number CR-814388-02-1. Dr. Alan Carlin and Dr. Ann Fisher provided valuable guidance in the design of the project, and Dr. Doyle Graham and Dr. Douglas Anthony offered generous assistance in communicating the medical consequences of nerve disease to subjects. Jon LaScala assisted superbly in the administration and analysis of the survey, and Patricia Born provided additional computer programming assistance.     

Insurer ambiguity and market failure

A series of studies investigate the decision processes of actuaries, underwriters, and reinsurers in setting premiums for ambiguous and uncertain risks. Survey data on prices reveal that all three types of these insurance decision makers are risk averse and ambiguity averse. In addition, groups appear to be influenced in their premium-setting decisions by specific reference points such as expected loss and the concern with insolvency. This behavior is consistent with a growing analytical and empirical literature in economics and decision processes that investigates the role that uncertainty plays on managerial choices. Improved risk-assessment procedures and government involvement in providing protection against catastrophic losses may induce insurers to reduce premiums and broaden available coverage.This article is part of a larger effort supported by the National Science Foundation on The Role of Insurance, Compensation, Regulation, and Protective Behavior in Decision Making about Risk and Misfortune. We greatly appreciate the many helpful comments and suggestions by our colleagues on the project: Jon Baron, Colin Camerer, Neil Doherty, Jack Hershey, Eric Johnson, and Paul Kleindorfer. Support from NSF Grant #SES8809299 is gratefully acknowledged.     

Ambiguity aversion in the small and in the large for weighted linear utility

The widely observed preference for lotteries involving precise rather than vague of ambiguous probabilities is called ambiguity aversion. Ambiguity aversion cannot be predicted or explained by conventional expected utility models. For the subjectively weighted linear utility (SWLU) model, we define both probability and payoff premiums for ambiguity, and introduce alocal ambiguity aversion function a(u) that is proportional to these ambiguity premiums for small uncertainties. We show that one individual's ambiguity premiums areglobally larger than another's if and only if hisa(u) function is everywhere larger. Ambiguity aversion has been observed to increase 1) when the mean probability of gain increases and 2) when the mean probability of loss decreases. We show that such behavior is equivalent toa(u) increasing in both the gain and loss domains. Increasing ambiguity aversion also explains the observed excess of sellers' over buyers' prices for insurance against an ambiguous probability of loss.     

Do Trade Union Leaders Violate Subjective Expected Utility? Some Insights From Experimental Data

This paper presents the results of two experiments designed to test violations of Subjective Expected Utility Theory (SEUT) within a sample of Italian trade union delegates and leaders. Subjects priced risky and ambiguous prospects in the domain of gains. Risky prospects were based on games of chance, while ambiguous prospects were built on the standard Ellsberg paradox and on event lotteries whose outcomes were based either on the results of a fictional election or on the future results of the 1999 European Parliamentary election in Italy and the U.K. The experiments show that, although risky prospects were priced at their expected values on average, trade union delegates and leaders did violate SEUT when assessing ambiguous prospects. Moreover, their behaviour depended on the source of uncertainty (Ellsberg paradox vs. electoral results; fictional vs. real election; Italy vs. U.K. election outcomes). We discuss the implications of these results for the economic theory of the trade union.     

Evidence for multiple strategies in choice under risk

This paper describes an experimental study that yields evidence for the coexistence of two decision strategies of choice under risk. Under the first strategy, choices are made based on aspiration levels – a heuristic that simplifies risky decisions. Under the second strategy, which can be used when aspiration levels are not determinative, choices are made based on preferences for positive skewness. Our model fitting confirms the efficacy of a two-pronged approach that can marshal either strategy depending on specific features of the risky prospects under consideration.     

Choices Under Ambiguity With Familiar And Unfamiliar Outcomes

This paper considers a decision-making process under ambiguity in which the decision-maker is supposed to split outcomes between familiar and unfamiliar ones. She is assumed to behave differently with respect to unfamiliar gains, unfamiliar losses and customary (familiar) outcomes. In particular, she is supposed to be pessimistic on gains, optimistic on losses and ambiguity neutral on the familiar outcomes. A generalization of the usual Choquet Integral is formalized when the decision maker holds capacities and probabilities. A characterization of the decision-maker’s behavior is provided for a specific subset of capacities, in which it is shown that the decision-maker underestimates the unfamiliar outcomes while is linear in probabilities on customary ones.     

It is Whether You Win or Lose: The Importance of the Overall Probabilities of Winning or Losing in Risky Choice

Imagine that you own a five-outcome gamble with the following payoffs and probabilities: ($100, .20; $50, .20; Imagine that you own a five-outcome gamble with the following payoffs and probabilities: ($100, .20; $50, .20; $0, .20; –$25, .20; –$50, .20). What happens when the opportunity to improve such a gamble is provided by a manipulation that adds value to one outcome versus another outcome, particularly when the opportunity to add value to one outcome versus another outcome changes the overall probability of a gain or the overall probability of a loss? Such a choice provides a simple test of the expected utility model (EU), original prospect theory (OPT), and cumulative prospect theory (CPT). A study of risky choices involving 375 respondents indicates that respondents were most sensitive to changes in outcome values that either increased the overall probability of a strict gain or decreased the overall probability of a strict loss. These results indicate more support for OPT rather than CPT and EU under various assumptions about the shape of the utility and value and weighting functions. Most importantly, the main difference between the various expectation models of risky choice occurs for outcomes near the reference value. A second study of risky choice involving 151 respondents again demonstrated the sensitivity of subjects to reducing the probability of a strict loss even at the cost of reduced expected value. Consequently, we argue that theories of how people choose among gambles that involve three or more consequences with both gains and losses need to include measures of the overall probabilities of a gain and of a loss.JEL Classification  D81     

Gender differences in ambiguity aversion under different outcome correlation structures

This paper studies the impact of different outcome correlation structures on gender differences in ambiguity aversion. We conducted an investment game with two separate treatments. In the uncorrelated treatment, the outcomes of the investment game were determined individually. In the correlated treatment, the outcomes of the investment game were determined collectively within a reference group. From an evolutionary perspective, men should be more concerned about relative outcomes, because their reproductive success mainly depended on their relative standing within society. Women, by contrast, should be more concerned about absolute outcomes, because their reproductive success was mainly linked to their access to resources for themselves and their children. Therefore, we predict that the type of outcome correlation structure has a larger impact on men than on women. In particular, we hypothesize that men are less ambiguity averse under an uncorrelated outcome structure. In this situation, the ambiguous alternative should be more attractive, because it potentially reduces inequality and thereby improves men’s relative standing within society. Women’s choices should not be significantly affected by different outcome correlation structures. Both hypotheses are supported by evidence from laboratory experiments.     

Willingness-to-pay and willingness-to-accept for risky and ambiguous lotteries

Former studies have shown that people tend to give buying prices that are lower than selling prices. In our study, we investigate if this willingness-to-accept and willingness-to-pay disparity is affected by ambiguity. Using a Becker, DeGroot, and Marschak procedure, we elicit buying, selling, short-selling, and short-buying prices. The results indicate that subjects clearly distinguish between risky and ambiguous lotteries and the different ways in which lotteries are framed. However, the average WTA/WTP ratios are remarkably close for all lotteries considered, as well as for negative and positive framing.     

From fun to fraught: marketing to kids and regulating “risky foods” in Canada

ABSTRACT

In an era of industrialized food production, ultra-processed foods, “Big Food” marketing, and growing obesity rates, food has come to be framed as an object of risk – and as an object of regulation. Such reframing has fascinating implications related to issues of responsibility and decision making, especially when it comes to children’s food. This article probes the relationship between representation, regulation and “risky” consumption with respect to children’s food. I examine how child-targeted foods become framed as “risky” and what counts as “risky” food messaging under Health Canada’s commitment to restrict the marketing of unhealthy foods to children. Detailing the tension between food as a risk object and food as a child object, I suggest how issues of semantic provisioning and the politics of the unseen work to complicate and destabilize the (seemingly) straightforward process of prohibiting unhealthy food marketing to children.     

How Do Information Ambiguity and Timing of Contextual Information Affect Managers’ Goal Congruence in Making Investment Decisions in Good Times vs. Bad Times?

Information ambiguity is prevalent in organizations and may influence management decisions. This study draws upon research on information bias and ambiguity research to empirically test how information ambiguity and non-financial factors (e.g., interpersonal information) affect managers’ capital budgeting decisions when in good vs. bad times. Ninety-two managers completed two experiments. In Experiment One, the information was presented sequentially. Our results show that without the presence of non-financial factors, managers tend to maximize the firm value. After receiving non-financial factors, a significant number of managers switched to the self-serving option in good times (the gain condition) but stayed with firm-value maximization in bad times (the loss condition). In Experiment Two, the information was presented simultaneously in the presence and absence of ambiguity. We found that in the presence of ambiguity, the information presentation has no impact on managers’ self-serving bias in good times or their firm-value maximization tendency in bad times. Interestingly, we also observed managers’ use of interpersonal information even in the absence of ambiguity.JEL Classification: D8     

Ambiguity Aversion in the Field of Insurance: Insurers’ Attitude to Imprecise and Conflicting Probability Estimates

This article presents the results of a survey designed to test, with economically sophisticated participants, Ellsberg’s ambiguity aversion hypothesis, and Smithson’s conflict aversion hypothesis. Based on an original sample of 78 professional actuaries (all members of the French Institute of Actuaries), this article provides empirical evidence that ambiguity (i.e. uncertainty about the probability) affect insurers’ decision on pricing insurance. It first reveals that premiums are significantly higher for risks when there is ambiguity regarding the probability of the loss. Second, it shows that insurers are sensitive to sources of ambiguity. The participants indeed, charged a higher premium when ambiguity came from conflict and disagreement regarding the probability of the loss than when ambiguity came from imprecision (imprecise forecast about the probability of the loss). This research thus documents the presence of both ambiguity aversion and conflict aversion in the field of insurance, and discuses economic and psychological rationales for the observed behaviours.     

Uncertainty Aversion Vs. Competence: An Experimental Market Study

Heath and Tversky (1991, Journal of Risk and Uncertainty 4:5–28) posed that reaction to ambiguity is driven by perceived competence. Competence effects may be inconsistent with ambiguity aversion if betting on own judgement is preferred to betting on a chance event, because judgemental probabilities are more ambiguous than chance events. This laboratory experiment analyses whether ambiguity affects prices and volumes in a double auction market, and contrasts ambiguity aversion to competence effects. In order to test for the presence of competence effects, in the experiment uncertainty is tied to the realisation of events about which the decision maker is more or less knowledgeable. Two experiments are presented: in the first, knowledge is exogenous, whereas in the second the knowledge judgement is endogenous. Market prices provide evidence in favour of the competence hypothesis only when competence is self-assessed. Comparable volumes are observed in both experiments.      

Ambiguity and risk taking in organizations

Kunreuther, Meszaros, and Hogarth (1993) argue that insurers are risk averse and ambiguity averse, and that they use cognitive reference points and constraints in making pricing decisions. They further claim that insurer ambiguity may be a factor that has a role in market failure at the industry level. Arguably, ambiguity may be an important aspect of decision behavior. In this article, research on managerial risk taking is reviewed with a focus on the relationship between ambiguity and risk taking. In particular, the effects of the organizational and institutional context are highlighted. It is argued that the political aspects of insurer decision behavior should be considered as well. Implications for further study and understanding of decision making are discussed.     

Preference reversals and probabilistic decisions

Preference reversals occur when different (but formally equivalent) elicitation methods reveal conflicting preferences over two alternatives. This paper shows that when people have fuzzy preferences, i.e. when they decide in a probabilistic manner, their observed decisions can generate systematic preference reversals. A simple model of probabilistic choice and valuation can account for a higher incidence of standard (nonstandard) preference reversals for certainty (probability) equivalents and it can also rationalize the existence of strong reversals. An important methodological contribution of the paper is a new definition of a probabilistic certainty/probability equivalent of a risky lottery.