Explaining the Erectile Responses of Rapists to Rape Stories: The Contributions of Sexual Activity, Non-Consent, and Violence with Injury

Grant T. Harris, Martin L. Lalumière, Michael C. Seto, Marnie E. Rice, Terry C. Chaplin

In phallometric research, rapists have a unique pattern of erectile responses to stimuli depicting sexual activities involving coercion and violence. In this study, we attempted to determine the cues that control rapists' erectile responses to rape stories in the laboratory. A total of 12 rapists and 14 non-rapists were exposed to recorded audio scenarios that systematically varied with regard to the presence or absence of three orthogonally varied elements: sexual activity and nudity, violence and injury, and expression of non-consent. As expected from prior research, an index computed by subtracting participants' greatest mean responses to stories describing mutually consenting sexual activity from their greatest mean responses to stories describing rape was much higher among rapists than non-rapists. Both groups showed larger responses when stories involved sexual activity and nudity, but neither group exhibited a preference for cues of violence and serious injury, or for cues of non-consent. The element that produced the larger group difference, however, was the presence or absence of active consent. The results indicated that a sexual interest in (or indifference to) non-consent is at least as central to accounting for the unique sexual orientation of rapists as is sexual responding to violence and injury.