Abstract # 2414 Poster # 108:

Scheduled for Friday, June 20, 2008 05:00 PM-07:00 PM: Session 12 (Ball Rooms A and B) Poster Presentation

How capuchin monkeys (Cebus apella) categorize visual images of themselves: In-group vs. out-group

J. J. Pokorny and F. B. de Waal
Living Links / Emory University / Yerkes National Primate Research Center, Atlanta, GA 30322, USA
     Individuals within a group must differentiate between in-group and out-group members, as outsiders pose a threat to a group’s resources.  We have previously shown that capuchin monkeys (Cebus apella) can categorize visual images of conspecifics as members of their own group (in-group) or as members of another group (out-group).  As a follow-up, the current study investigated how capuchins (n=3) categorized their own image, being either from the in-group or from the out-group.  This was achieved using an oddity task on a touch-sensitive monitor in which digital images of conspecific faces were presented and monkeys could select the image that did not match the others. By scoring which image was selected as ‘odd’ we could determine whether they viewed their own image as matching the in-group or out-group. Fifty probe trials that included their own image were presented over five testing sessions.  Subjects were rewarded for any response on probe trials, eliminating learning effects. Data suggests that overall, subjects categorized their own image as an in-group member [G tests, a=0.05], though this was not routinely consistent among subjects.  In general, this is in accord with the finding that capuchins do not view their own mirror reflection as a stranger (de Waal et al., 2005), or out-group member.  Prior experience with their reflection may allow subjects to classify their own image as belonging to the in-group.