Effects of simultaneous and successive stimulus presentation on visual discriminations by aphasic patients.

Abstract

In order to determine whether aphasic and nonaphasic subjects would perform differentially in simultaneous and successive discrimination tasks, 10 aphasic and 10 nonaphasic hospital patients performed in a successive and a simultaneous discrimination task in which 2 stimuli were presented on each trial, and in a successive discrimination with a single stimulus presented on each trial. Aphasic and nonaphasic subjects learned the successive discrimination task with a single stimulus faster than the other two discriminations. When the discrimination involved two stimuli, simultaneous presentation of stimuli resulted in faster learning by aphasic subjects than did successive presentation. Learning of visual discriminations by aphasic and nonaphasic subjects appeared to occur all at once, rather than as gradual improvement over trials. The hypothesis that aphasic subjects would have difficulty with inhibition of responses to negative discriminative stimuli was not supported.