The performance of amnesic subjects on tests of experimental amnesia in animals: delayed matching-to-sample and concurrent learning.

A group of amnesic Korsakoff subjects and a group of alcoholic controls were trained on a test of visual recognition, delayed matching-to-sample with trial unique stimuli. This test was modelled on comparable tasks used in the development of animal models of human amnesia. It was found that the Korsakoff subjects were severely impaired when the task difficulty was increased by lengthening the retention delay beyond 10 sec or by increasing the number of items intervening between sample presentation and test. The amnesic subjects were also impaired on the acquisition of a set of concurrent visual discriminations. These results bear clear similarities to those obtained from experimental amnesic syndromes in monkeys.