Size Discrimination and Transposition in Monkeys with Striate and Temporal Lesions

In transposition testing the LS monkeys, and to a lesser extent the IT monkeys, differed from the N monkeys in that they showed better size transposition.

Abstract

Monkeys with inferotemporal (IT) lesions, lateral striate (LS) lesions and unoperated controls were trained to discriminate between two stimuli differing in size and were then tested for size transposition to stimuli altered in absolute size, in shape and in linear dimensions (height and width). The LS animals were more severely impaired than were the IT animals in learning the discrimination. In transposition testing the LS monkeys, and to a lesser extent the IT monkeys, differed from the N monkeys in that they showed better size transposition. It is suggested that this paradoxical enhancement of transposition following cortical lesions might be due to an impairment in detecting differences between the training and test stimuli.