THE AVERAGED EVOKED CORTICAL RESPONSE TO COMPLEX VISUAL STIMULI

Abstract

ABSTRACT Averaged cortical evoked responses in man to repetitive informationally complex pictorial stimuli, as opposed to other visual stimulation, were obtained from scalp electroencephalographic (EEG) recordings. The method used involved the projection of lantern slides. Included were three different categories (indifferent scenic, repulsive medical, and nude female photographs) assumed to evoke, respectively, neutral, negative, and positive reactions in the normal young male subjects. In all subjects, recordings from occipital or occipitoparietal scalp leads consistently resulted in evoked response patterns to pictorial slides measurably differing from responses to these same slides made non‐associational through defocusing, or to blank light flashes. Responses to pictorial stimuli were also different than those to motivated observation of projected words, colors, or geometric patterns. The evoked responses to the three different categories of pictorial stimuli also showed significant differences. These differences were not as marked and were clearly replicable only for some subjects.