Quantification of the human orienting response to another human: lesioned and psychiatric patients compared to normals.

A method for eliciting, controlling, and quantifying the alpha suppression response to a human "real-person" stimulus is presented. Improved control is achieved by a feedback from the EEG response to the presentation of the stimulus. Quantification is comprehensive in that initial response and subsequent habituation for both latency and duration are described. Patients who had suffered a focal lesion but who had recovered sufficiently to travel from one hospital to another by taxi were compared with hospitalized psychiatric patients and normal volunteers. Lesioned patients showed less EEG response to visual stimuli than did the other groups, even with an evocative, real-person stimulus. The differences among the three groups were most evident at the onset of stimulation and less so after habituation had occurred.