Social Categorization
Capuchin monkeys regularly encounter other groups in the wild and respond in an agonistic manner not normally directed toward in-group members. This behavioral evidence suggests that capuchins have a concept of familiarity, or in-group vs. out-group. The capuchin colony at Yerkes houses two groups of capuchins, with approximately 15 individuals in each group, much like what one would find in the wild. Therefore, we investigated knowledge of conspecifcs by looking at our capuchins’ ability to categorize individuals based on group membership. The task was presented to the subjects in an oddity paradigm, much like the face recognition study. In this case, we presented one in-group member with three different out-group members and vice versa. We found that subjects were able to categorize the images based on whether the individual depicted was from the in-group or the out-group relative to the subject (Pokorny, J. J. & de Waal, F. B. M., in revision).
