Plethysmographic Assessment of Incarcerated Nonsexual Offenders: A Comparison with Rapists

Abstract

Plethysmographic testing was completed on 100 research participants from the same medium-security prison population, 50 of whom were incarcerated for nonsexual offenses. In order to strengthen the validity of the research, only participants who achieved full arousal were included in the sample, and the percentage of full erection scores, as well as the Rape Index, were examined. The resulting sexual arousal profiles revealed striking similarities between rapists and control participants, indicating that deviant arousal alone did not distinguish these sexual offenders from nonsexual offenders. The only marked difference between the two groups was in the almost-perfect ability of control participants to inhibit deviant arousal and the weak ability of sexual offenders to accomplish this. The suggestion was advanced that a determination of an offender's ability to inhibit deviant arousal may be the only aspect of plethysmographic testing which has practical application in the assessment of rapists.