Penile sufficiency: an operational definition

In an effort to obtain a more precise definition of erectile sufficiency for vaginal penetration 19 normal men were exposed to an erotic videotape and recordings of penile tumescence were obtained. The subjects were instructed to signal with a push button switch when they had attained an erection they judged sufficient for penetration. They were asked to signal a second time when a full erection had been reached. The results showed that in all but 1 case maximal tumescence was recorded polygraphically before the subjects signaled sufficiency. In addition, there was a considerable interval between the perception of sufficiency and the perception of a full erection during which, nevertheless, no further changes could be detected by strain gauge measurement. These data suggest that standard assessment techniques are not sensitive to penile changes in the upper ranges of tumescence. Of interest to the developing area of diurnal penile tumescence for the etiological diagnosis of impotence was the observation that a significant percentage (37 per cent) of normal subjects were unable to achieve a full erection during visual sexual stimulation under laboratory conditions.