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In decision-making under uncertainty, economic studies emphasize the importance of risk in addition to expected reward. Studies in neuroscience focus on expected reward and learning rather than risk. We combined functional imaging with a simple gambling task to vary expected reward and risk simultaneously and in an uncorrelated manner. Drawing on financial decision theory, we modeled expected reward as mathematical expectation of reward, and risk as reward variance. Activations in dopaminoceptive structures correlated with both mathematical parameters. These activations differentiated spatially and temporally. Temporally, the activation related to expected reward was immediate, while the activation related to risk was delayed. Analyses confirmed that our paradigm minimized confounds from learning, motivation, and salience. These results suggest that the primary task of the dopaminergic system is to convey signals of upcoming stochastic rewards, such as expected reward and risk, beyond its role in learning, motivation, and salience.

Abstract We examine the risky choices of contestants in the popular TV game show "Deal or No Deal" and related classroom experiments. Contrary to the traditional view of expected utility theory, the choices can be explained in large part by previous outcomes experienced during the game. Risk aversion decreases after earlier expectations have been shattered by unfavorable outcomes or surpassed by favorable outcomes. Our results point to reference-dependent choice theories such as prospect theory, and suggest that path-dependence is relevant, even when the choice problems are simple and well-defined, and when large real monetary amounts are at stake.

Abstract. We design experiments to jointly elicit risk and time preferences for the adult Danish population. We find that joint elicitation results in estimates of discount rates that are dramatically lower than those found in previous studies. Estimation of latent time preferences requires that one specify a theoretical structure to understand risk and time choices, but we show that our main results, based on exponential discounting and expected utility theory, are robust to popular alternative specifications such as hyperbolic discounting and prospect theoretic formulations of choice under uncertainty. We also report evidence favoring standard, exponential discounting over hyperbolic. These results have direct implications for attempts to elicit time preferences, as well as debates over the appropriate domain of the utility function when characterizing risk aversion and time consistency.

ABSTRACT Explanations of poverty, growth and development depend on the assumptions made about individual preferences and the willingness to engage in strategic behaviour. Economic experiments, especially those conducted in the field, have begun to paint a picture of economic agents in developing communities that is at variance with the traditional portrait. We review this growing literature with an eye towards preference-related experiments conducted in the field. We also offer lessons on what development economists might learn from experiments. We conclude by sharing our thoughts on how to conduct experiments in the field and then offer a few ideas for future research.

We review the experimental evidence on risk aversion in controlled laboratory settings. We review the strengths and weaknesses of alternative elicitation procedures, the strengths and weaknesses of alternative estimation procedures, and finally the effect of controlling for risk attitudes on inferences in experiments. Attitudes to risk are one of the primitives of economics. Individual preferences over risky prospects are taken as given and subjective in all standard economic theory. Turning to the characterization of risk in applied work, however, one observes many restrictive assumptions being used. In many cases individuals are simply assumed to be risk neutral;1 or perhaps to have the same constant absolute or relative aversion to risk.2 Assumptions buy tractability, of course, but at a cost. How plausible are the restrictive assumptions about risk attitudes that are popularly used? If they are not plausible, perhaps there is some way in which one can characterize the distribution of risk attitudes so that it can be used to analyze the implications of relaxing these assumptions. If so, such characterizations will condition inferences about choice behavior under uncertainty, bidding in auctions, and behavior in games.

Experimentally elicited discount rates are frequently higher than what one would infer from market interest rates and seem unreasonable for economic decision-making. Such high rates have often been attributed to dynamic inconsistency, as in present bias and hyperbolic discounting. A commonly recognized bias of standard elicitation techniques is the use of linear preferences for identification. We present a novel methodology for identifying time preferences, both discounting and utility function curvature, from simple allocation decisions. We estimate annual discount rates substantially lower than normally obtained, and limited though significant utility function curvature. Additionally, our data show no evidence of dynamic inconsistency.

This paper investigates consumer switching costs in the context of health insurance markets, where adverse selection is a potential concern. Switching costs contribute to poor choices when the market environment changes and consumers do not adjust appropriately. Though previous work has studied the problems of adverse selection and consumer choice inadequacy in isolation, these phenomena interact in a way that directly impacts market outcomes. We use a unique proprietary panel data set with the health plan choices and medical utilization of employees at a large firm to show that (i) switching costs are large and (ii) switching costs significantly impact the degree of adverse selection in equilibrium. We estimate a structural choice model to jointly quantify switching costs, risk preferences, and health risk in the population. We use the output of this model to study the welfare impact of an information provision policy that nudges consumers toward better decisions by reducing switching costs. In a partial equilibrium setting where observed plan prices are held fixed, we find that a policy that completely eliminates switching costs improves consumer welfare by 10%. In a general equilibrium setting where insurers change prices to reflect the expenses of their risk pools, the same policy (i) exacerbates

This paper measures the economic impacts of social pressures to share income with kin and neighbors in rural Kenyan villages. We conduct a lab experiment in which we randomly vary the observability of investment returns to test whether subjects reduce their income in order to keep it hidden. We find that women adopt an investment strategy that conceals the size of their initial endowment in the experiment, though that strategy reduces their expected earnings. This effect is largest among women with relatives attending the experiment, who invest 22 percent less when income is observable. At the village level, the extent to which experimental subjects engage in income hiding within the experiment is negatively associated with the probability of skilled employment and the value of household assets.