Transfer of a learning set between drug states in monkeys.

Four adult male rhesus monkeys, while in either a pentobarbital-induced drug state or a saline control state, were trained on a series of 12 oddity problems. Tests in the opposite drug or saline state were administered after acquisition of each problem in order to determine the amount of transfer between the disparate states. All tests included presentation of problems not previously seen (novel problems). Tests 2-11 also included presentation of problems trained beyond criterion level (overtrained problems). During early tests only the overtrained problems exhibited transfer to the opposite drug or saline state. However, during the later tests, as the monkeys acquired the learning set in the training state, both the novel and overtrained problems were correctly solved in the test state. This indicates that the concept of oddity, rather than solution of specific problems, transferred between drug states. Interestingly, the overtrained problems exhibited greater transfer on the later tests than on early tests. This may suggest that the transfer due to overtraining is not the same as the transfer due to acquisition of the oddity learning set.