Discrimination learning and multiple reversals in young adult and older monkeys (Macaca arctoides)

Two groups of five young adult an older stumptailed macaques (Macaca arctoides) were tested on a visual discrimination task followed by a reversal upon attainment of criterion; task and reversal were repeated until 20 reversals with the same pair of objects had been completed. Both groups required more trials to learn the first reversal than the original discrimination, with no significant difference between the groups. Older monkeys tended to show more perseverative errors on early reversals, but a striking improvement in their scores across successive blocks of reversals culminated in performances virtually indistinguishable from those of the young group by the end of testing.