ARE ECONOMISTS DIFFERENT, AND IF SO, WHY

Do economists behave differently from noneconomists? Some evidence suggests they do. In a well-known 1981 study in the Journal of Public Economics, Gerald Marwell and Ruth E. Ames found that free riding was significantly greater among a group of economics graduate students than among other student groups in their experiments. Marwell and Ames offered two conjectures for why economics students might in fact behave differently. First, students who are particularly concerned with economic incentives might self-select into economics. In addition, or alternatively, economics students might adapt their behavior over time to the basic axioms of the theories they study. These conjectures may be called respectively the selection and learning hypotheses. In this paper we explore whether Marwell and Ames' result is robust-whether economists are indeed different. In particular, we use a simple ultimatum bargaining experiment to test whether economics students behave more in accordance with predictions of the rational/self-interest model of economics. Finding that a behavioral difference does exist, we then conduct tests to discriminate between the selection and learning hypotheses