Impairment in sampling visual stimuli in monkeys with inferotemporal lesions

Monkeys with inferotemporal (IT) lesions and their controls, monkeys with partial removal of striate cortex (LS) and unoperated monkeys, were trained to discriminate between two stimulus compounds differing in brightness near the response site and in hue, distant from the response site. In subsequent discrimination testing, only the distant cue (hue) was available. All animals learned the original discrimination rapidly. However, in the discrimination test, the IT monkeys made significantly more errors than did the unoperated monkeys, while the LS monkeys were unimpaired. These findings support the view that IT lesions impair visual search. Once the IT monkeys learned the test discrimination, they were not impaired in a series of subsequent tests in which the area of the distant cue was successively reduced.