To model an individual's choices under uncertainty, theorists typically assume the choices made maximize the individual's utility. While frequently a good description of observed behavior, there are instances where people instead choose alternatives in proportion to their associated probabilities of reward. This probability matching behavior is sub-optimal. Probability matching behavior and optimal behavior would both result depending on the time available to make decisions (where more time produces more optimal decisions) if individuals base their choices on a sampling algorithm. In this Doctoral Dissertation Improvement grant, the PI will test whether such an algorithm is responsible for observed choices and, furthermore, whether people are optimally suboptimal (i.e., optimal in their decision regarding when to be more, or less, optimal.
To test these hypotheses, experimental subjects will be assessed in terms of how flexible they are at making tradeoffs between speed and accuracy in motor decisions under uncertainty and how generic decision processes are across decision domains. Subjects are then tested for whether their decisions under cognitive stress deteriorate to probability-matching, as predicted by the proposed algorithm. Finally, subjects will be tested using fMRI to determine whether one brain structure represents expected utility arising from different sources of uncertainty. This research holds promise for reconciling models of humans as ideal agents with established failures and limitations of human decision-making.