Problem solving in elderly sophisticated and naive monkeys.

Elderly (greater than 23 years) rhesus monkeys, some of whom had previous learning test experience, were tested on a standardized battery of discrimination and concept-formation tasks, and their performance was compared with that of test-naive middle-aged (15 years) and juvenile (2 years) monkeys. Naive elderly monkeys performed more poorly on virtually all tasks compared to their younger counterparts. In contrast, test-experienced elderly monkeys outperformed both middle-aged and juvenile monkeys on those problem types with which they had limited previous experience, despite the fact that 8-10 years had passed since their prior training. However, test-experienced elderly monkeys did not display superior performance on new tests that approximated visual acuity or assessed delayed discrimination capabilities.