Abstract # 43:

Scheduled for Saturday, September 13, 2014 07:00 PM-09:00 PM: Session 11 (Decatur B) Poster Presentation


J. P. Jefferson1, A. Riddle2, A. Paukner2 and S. J. Suomi2
1Animal Behavior Graduate Group, University of California, Davis, Davis, CA 95616, USA, 2Laboratory of Comparative Ethology, National Institute of Child Health and Human Development, Poolesville, MD
     Capuchin monkeys fur rub by vigorously biting and rubbing stimulating materials into their pelage. A discrimination task was used to infer the affective state of five captive brown capuchins during fur rubbing. During training, monkeys chose between two food wells baited with nothing on one side and either a high (grape) or low (apple) reward on the other. Monkeys could infer the quality and location of the reward based on a visual stimulus (long/short rectangle) displayed for each trial. An ambiguous stimulus (medium rectangle) with no reward was presented randomly throughout a testing session. Monkeys were tested following five minutes with a) no stimulus (neutral), b) a marshmallow filled toy (positive), and c) an onion (fur rub). A series of chi-square tests (alpha=0.05) revealed that on test trials, one capuchin had a significant ‘pessimistic-like’ (low reward) bias, and three showed an ‘optimistic-like’ (high reward) bias. Per individual, cognitive bias increased in the marshmallow condition (ranging between 8-42%), suggesting that the positive control may have intensified both negative and positive emotions. However, a chi-square test-for-independence indicated that this relationship was only significant for monkeys with ‘pessimistic-like’ bias. Conversely, monkeys with ‘optimistic-like’ judgment that fur rubbed increased their positive choices between 0-25% and monkeys with ‘pessimistic-like’ judgment did so by 33% and 16%. Preliminary findings suggest that fur rubbing may increase positive affective states in capuchin monkeys.