Instructional control of an autonomic sexual response.

Four of seven human male subjects developed full penile erections when exposed to erotically stimulating motion pictures. Changes in penile size were detected by a mercury strain gauge transducer and automatically recorded on a continuous paper record. When instructed to inhibit penile erection in the presence of such effective stimulus films, every subject was able to reduce his erection by at least 50%. This inhibition was apparent as long as the instructions were in effect; when the instructions were removed and the film reshown, the erection returned almost to its maximum state. This was true whether the films were presented as few as three or as many as nine times in succession. When instructed to develop an erection in the absence of a film, every subject was able to do so, each reaching a peak of about 30% of his maximum. Such erections had longer latencies to the peak produced and lower maximum levels than those elicited by a film.