People often face choices between alternatives that involve various degrees of risk. In such situations, motivational variables, including those related to a person's biological needs, economic goals or requirements, or social aspirations, may influence whether they prefer a high-risk or low-risk option. For example, when people make choices under dire, high-need conditions (e.g., a hunter choosing between prey types while facing starvation, a business manager choosing between investments while facing bankruptcy, an officer choosing between military strategies while under siege, or a doctor choosing between therapies while treating an advanced disease), they may be more likely to choose riskier options than under better conditions because only risky options can produce sufficient gains. Although decision researchers have long acknowledged that motivational variables may influence risky choice, analyzing their effects has been complicated by the difficulty of assessing an individual's goals or requirements. As a result, precisely how motivational variables affect risk taking, and whether people make optimal choices under different motivational states is not well understood.
One approach to studying the effects of motivational variables on human risky choice is suggested by research in the field of behavioral ecology, specifically optimal foraging theory. Behavioral ecologists, who analyze behavior from an evolutionary perspective, have studied risk-sensitive foraging (food-seeking) behavior in nonhumans and how a motivational state known as an energy budget affects behavior. An energy-budget is the relation between an organism's expected energy gains and reserves, and its energy needs. Energy-budget research has focused on testing an optimization model known as the energy-budget rule. Experiments with various species have shown that when energy-budgets are manipulated, risk preferences change in a manner consistent with the predictions of the energy-budget rule, i.e., risky choice appears biologically adaptive. For ethical reasons no experiments have investigated the effects of energy-budget on human risky choice, but recently researchers have extended this analysis to human behavior by simulating energy-budgets with monetary "earnings" budgets. These studies not only showed that risk preferences were consistent with the predictions of the energy-budget rule, but that multi-stage (dynamic) choices were well described by dynamic optimization models. These findings suggest that optimal foraging theory may provide a useful methodological and conceptual framework for analyzing the effects of motivational variables on human risky choice. The present research further evaluates the utility of this approach. Four experiments investigate risky choice in humans as motivational states (earnings-budgets) are manipulated. These experiments will extend the results of earlier studies, explore the generality of the predictions of risk-sensitive optimization models, and further test a unique methodology for studying human risky choice and dynamic decision making. This research may facilitate cross-species comparisons, and help promote the integration of psychological, evolutionary, and economic approaches to risk. The ultimate goals are to improve our understanding of decision-making processes and better predict the conditions under which people prefer or avoid risk.
