Date of Award

Spring 1999

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

William M Baum


This dissertation presents an experimental analysis of social behavior. The behavior is called Group Choice (Baum & Kraft, 1998) and the analysis is a social foraging model called the Ideal Free Distribution (IFD; Fretwell & Lucas, 1970). The IFD is a social foraging model that describes the distribution of a group of foragers in a patchy environment. Group Choice describes group members engaging in two behaviors. The IFD suggests that group members engage in two behaviors in the same relative relation to the consequences obtained from those behaviors. The IFD of Group Choice is analogous to the Matching Law analysis of individual choice (Baum, 1974; Herrnstein, 1961, 1970; Kennedy & Gray, 1993).

The results showed consistent IFD matching of the groups' choices to the point distributions when unequal amounts of points were shared among subgroup members (Experiments 1, 2, 7a, and 7b). In contrast, the groups undermatched point distributions when the points were allocated probabilistically. Groups tended to match to the same degree regardless of the type of behavior alternative (i.e., sitting in chairs or choosing cards). Not being able to ideally distribute (imperfect solutions) tended to reduce group sensitivity to the distribution of points. Assigning different competitive weights to participants did not have an impact on group choice. Overall, the groups' choices before knowing what others chose were more variable, but similar to the choices made after knowing what others chose. Analyses of individuals' consistency in preferences and obtained points from block-to-block of trials failed to reveal order on the individual level that could explain the group level results. A promising analysis of individuals' choices between alternatives and obtained points from those alternatives also did not reveal a satisfactory explanation for group level results.

The analogy between an IFD analysis of Group Choice and a Matching Law analysis of individual choice may be far reaching. Whereas an individual's responses match the relative consequences, group members' behavior match the relative resources. Basic equations for both relations can be expressed in ratio form and generalized to account for deviations as a power function. Undermatching is the common result for both lines of research. Whereas the Matching Law describing individual choice became the foundation for the quantification of the Law of Effect and decades of fruitful research, it remains to be seen if the IFD of Group Choice stimulates similar progress. If the analogy between the Matching Law analysis of individual choice and the IFD of Group Choice is thoroughgoing, this research may provide the foundation for the quantification of a social level Law of Effect. (Abstract shortened by UMI.).