Abstract
We provide evidence that a personality trait, aggression, has a first-order effect on group financial decision making. In a laboratory experiment on group portfolio choice, highly aggressive subjects (measured by a standard psychology test) were much more likely to recommend risky investment strategies consistent with their own personal information, regardless of the information received by other group members. Outside of this group context, aggression had no effect on subject behavior. Thus, our aggression measure appears to capture an aggressive disposition, which seeks to dominate group decisions, rather than simply reflect risk attitudes or cognitive biases.