Abstract # 15:

Scheduled for Thursday, June 21, 2007 11:00 AM-11:15 AM: Session 3 (North Main Hall F/G) Symposium

Cooperative Problem Solving by Captive Cotton-top Tamarins (Saguinus oedipus): The Effects of Inequitable Rewards

K. A. Cronin
University of Wisconsin, Department of Psychology, 1202 W. Johnson St., Madison, WI 53706, USA
     We have previously demonstrated that adult pairs of cottontop tamarins coordinated their actions on a cooperative task that provided rewards to both actors, and that the tamarins appeared to understand the role of their partner in the cooperative act. Here we investigated the effects of various reward distributions on the tamarins’ performance on a cooperative pulling task to determine whether cooperation persists when both actors were not rewarded equally. A within-subjects design (N=4 pairs) was used to compare percent success and latency to solve the task across four payoff conditions (10 sessions of 8 trials per condition). The first condition provided equal rewards to both actors. In the second condition only one actor was rewarded, and the rewarded individual was alternated between sessions. In the third condition a monopolizable reward was delivered equidistant from both actors. In the fourth condition, a reward was repeatedly delivered to the same actor for all sessions. Significant differences in performance were found across conditions [planned paired t-tests, a=0.05]. The tamarins demonstrated the highest percent success and shortest latency to solve the task in the first condition, and the lowest percent success and longest latency to solve the task in the fourth condition. Although the tamarins demonstrated some selfish motivation during the experiment, unrewarded subjects continued to procure rewards for their partners and cooperation did not extinguish under any payoff condition. Support: NSF Graduate Research Fellowship, NIH MH029775.