Social facilitation of exploratory foraging behavior in capuchin monkeys (Cebus apella).

Much of the research on animal social learning focuses on complex cognitive functions such as imitation and emulation. When compelling evidence for such processes is not forthcoming, simpler processes are often assumed but rarely directly tested for. In this study we address the phenomenon of social facilitation, whereby the presence of a feeding conspecific is hypothesized to affect the motivation and behavior of the subject, elevating the likelihood of exploration and discovery in relation to the task at hand. Using a novel foraging task, sufficiently challenging that only just over half the subjects successfully gained food from it, we compared the performance of capuchin monkeys working either alone, or in a "social" condition where an actively feeding conspecific was in an adjacent chamber. Although similar numbers of subjects in these conditions were eventually successful during the 20 trials presented, the latency to successful solution of the task was over three times faster for monkeys in the social condition. The minority of monkeys that failed to learn (9/23) were then exposed to a proficient model. Only those older than 5 years provided evidence of learning from this. Accordingly, we obtained evidence for the social facilitation the study was designed to test for, and limited supplementary evidence for social learning in the older individuals who had not learned individually. These results are discussed in relation to other recent evidence for social learning in monkeys. (c) 2009 Wiley-Liss, Inc.