The role of learning in chuck call recognition by squirrel monkeys (Saimiri sciureus)

This study explored the role of learning in the development of chuck call r ecognition in squirrel monkeys. We experimentally exposed subjects of four different age classes, under controlled conditions, to the chuck calls of g enetically unrelated individuals of different social affinities. Using play back experimentation, we tested the hypothesis that subjects at different d evelopmental stages respond preferentially to the chuck calls of geneticall y unrelated familiar social group companions when compared to those of unfa miliar individuals from outside of the social group. Results demonstrated t hat adults vocally respond preferentially to the chuck calls of familiar so cial group members. Subadults behaviorally respond preferentially to the ch uck calls of close social associates within their social groups. Juveniles behaviorally responded more strongly to the playback of chuck calls arising from individuals within their colony when compared to the playback of 'sil ence.' Infants did not behaviorally or vocally respond preferentially to th e chuck calls of close social associates or other social group members. The se results demonstrate that learning plays a role in chuck call recognition in squirrel monkeys and may suggest that infants,gradually learn to acoust ically recognize social companions within their group.