The proposed research is directed at understanding the relationship between working memory and choice criteria in the context of a specific experimental situation, the rat radial-arm maze procedure. The radial maze involves rats choosing from a number of spatial locations, each of which initially contains a small amount of food. Rats quickly learn to avoid revisiting locations where they have already depleted the food. Previously visited locations are discriminated from unvisited locations using working memory. Characteristics of the working memory processes involved in this task have been extensively explored in previous investigations. The present experiments are designed to explore psychological process other than working memory that affect choice behavior in this maze. Data recently collected by my colleagues and me indicate that choices are also affected by the number of choices that have previously been made and by the distance that must be traveled between locations. We have interpreted these variables as affecting the choice criterion applied to potential choices, rather than affecting the quality of working memory. Such choice criterion effects may interact with memory in important and revealing ways, which will ultimately increase our understanding of fundamental aspects of memory performance, including that of humans. Thus, the proposed work is designed to understand the processes underlying these choice criterion effects and their relation to working memory.