Effects of prestriate and striate lesions on performance of simple visual tasks

Abstract

Seven rhesus monkeys were tested for their performance on simple visual tasks before and after striate lesions or extensive prestriate lesions that included foveal prestriate cortex. A food discrimination task measured their ability to distinguish a raisin from a steel nut and a simple perimetry test required them to retrieve a raisin from various parts of their visual field. We confirmed the results of others that after occipital decortication, a monkey can locate moving targets and distinguish objects that differ in “salience.” An unexpected finding was that prestriate lesions caused more severe and longer lasting visual deficits than did striate lesions as judged by the monkey's performance on these tasks and by informal observation.