There is a wealth of research in psychology demonstrating that agents process information with the aid of categories. In this paper we study this phenomenon in two parts. First, we build a model of how experiences are sorted into categories and how categorization affects decision making. Second,...

We conduct a laboratory experiment to examine how third-party ratings impact charity choice and donative behavior, particularly in regards to preferences for local charities. Subjects are given a menu of ten charities, with a mix of local and non-local organizations included. We vary whether...

We examine the combined effects of popularity and feelings of being important to reaching a goal by testing how people react to situations in which their own behavior is pivotal or not, as well as the popularity of the action. We conduct a laboratory experiment to cleanly fix beliefs about the...

We examine friendships and study partnerships among university students over several years. At the aggregate level, connections increase over time, but homophily on gender and ethnicity is relatively constant across time, university residences, and different network layers. At the individual...