Abstract # 146:

Scheduled for Sunday, September 14, 2014 07:00 PM-09:00 PM: Session 22 (Decatur B) Poster Presentation


C. E. Jones and D. Fragaszy
University of Georgia, Department of Psychology, Athens, Georgia 30605, USA
     Manipulation in primates is largely accomplished with the hands. Simple grips described by Napier (1956) address various ways that one hand can hold objects but this scheme does not fully describe manual grips. Compound grip, in which one object is held using two or more simple grips, or more than one object is held in one hand, has been described in general terms in several species of Old World primates. Compound grip requires that the digits operate independently to some degree to accommodate multiple objects or multiple grips. The objective of this study is to document prevalence and conditions promoting compound grip in tufted capuchin monkeys (Sapajus spp). To elicit compound grip two tasks were introduced to seven tufted capuchins. Task 1 involved depositing 1-4 craft balls into a small tube using one hand. Task two involved transferring a combination of 1-3 balls and rods to and from a flat surface. Grips were coded in slow motion video playback. All monkeys employed compound grip, holding more than one object in one hand when presented with two objects of different shapes/sizes. With three or four differently sized/shaped objects, they used simple grips, compound grips, or made errors. Findings confirm the presence of compound grip and suggest the limits of its effectiveness in this New World monkey. The limits of compound grips in other species are unknown.