Categorization and retrieval after selective inferotemporal lesions in monkeys

Two variations of a colour matching to sample task, with and without delay, were used to explore the deficits produced by bilateral foveal prestriate, posterior inferotemporal or anterior inferotemporal cortex lesions in monkeys. In the first task, 7 colours served as samples, but matching had to be done from only 4 alternative stimuli (7s x 4a); this task taxes the animal's ability to categorize information. In the second variation of matching to sample only 4 colours served as samples, but matching had to be done from amongst 8 alternative stimuli (4s x 8a); here, ability to retrieve information is tested. Task comparisons showed that the posterior inferotemporal group performed poorly on the 7s x 4a problem, whilst the AIT group were worse on the 4s x 8a task. It is concluded that posterior inferotemporal lesions disrupt categorization, whereas anterior inferotemporal lesions affect the retrieval of information.