Cognition requires scarce inputs, including time and concentration. Since cognition is costly, sophisticated decision-makers should use mental shortcuts, or heuristics, to reduce cognitive burdens. A model is proposed and tested that is motivated by these principles. It is believed this model achieves four goals. First, the model makes quantitative behavioral predictions and, hence, provides a precise alternative to the rational-actor hypothesis. Second, the model is psychologically plausible because it is based on the actual decisions algorithms that subjects claim to use. Third, the model is empirically testable; such a test is provided in this paper. Fourth, the model is broadly applicable, because it can be used to analyze decision problems that can be represented in tree form.

We combine two experiments and a survey to measure trust and trustworthiness—two key components of social capital. Standard attitudinal survey questions about trust predict trustworthy behavior in our experiments much better than they predict trusting behavior. Trusting behavior in the experiments is predicted by past trusting behavior outside of the experiments. When individuals are closer socially, both trust and trustworthiness rise. Trustworthiness declines when partners are of different races or nationalities. High status individuals are able to elicit more trustworthiness in others.