Discrimination Reversal Learning in Capuchin Monkeys (Cebus apella). Michael J. Beran, Emily D. Klein, Theodore A. Evans, Betty Chan, Timothy M. Flemming, Emily H. Harris, David A. Washburn, and Duane M. Rumbaugh

Learning styles in capuchin monkeys were assessed with a computerized reversal-
learning task called the mediational paradigm. First, monkeys were trained
to respond with 90% accuracy on a two-choice discrimination (A+B–). Then the
authors examined differences in performance on three different types of reversal
trials (A–B+, A–C+, B+C–), each of which offered differing predictions for
performance, depending on whether the monkeys were using associative cues or
rule-based strategies. Performance indicated that the monkeys mainly learned
to avoid the B stimulus during training, as the A–C+ condition produced the best
performance levels. Therefore, negative stimuli showed greater control over responding
after reversal and reflected a more associative rather than rule-based
form of learning.