Abstract # 137:

Scheduled for Sunday, September 18, 2011 11:00 AM-11:15 AM: Session 18 (Meeting Room 410) Oral Presentation


T. A. Evans1, M. J. Beran1, F. Paglieri2 and E. Addessi2
1Language Research Center, Georgia State University, P.O. Box 5010, Atlanta, GA 30302, USA, 2Istituto di Scienze e Tecnologie della Cognizione, CNR
     Chimpanzees will delay gratification to earn greater rewards, both when those rewards are edible food items and when they are tokens exchangeable later for rewards. We examined these capacities in eight captive capuchin monkeys using tests nearly identical to those used previously with apes. An experimenter transferred one item every 3 seconds from a container beyond the reach of a monkey to a container within reach of a monkey until the monkey took the items. We recorded how many items the monkeys obtained across four phases in which we varied the number of available items in a trial (5 or 50) and the type of items transferred between containers (edible rewards or tokens exchangeable for rewards). In trials involving 5 items of either type, most monkeys learned to accumulate all available items before taking them, and they exhibited similar means for each item type (food: 3.04; tokens: 3.24; Z = .631, n = 8, p = .528). However, in trials involving 50 items, monkeys earned nearly twice as many edible rewards (mean = 6.41) in comparison to exchangeable tokens (mean = 3.55; Z = 2.524, n = 8, p = .012). This contrasts with the performance of most chimpanzees, who seem to treat tokens as equivalent to edible rewards in these tasks. This difference may indicate that capuchin monkeys conceptualize tokens differently than chimpanzees.