Sexual Arousal in Rapists as Measured by Two Stimulus Sets

Abstract

Some uncertainty exists in the literature regarding the status of phallometric testing with rapists. Although Quinsey and colleagues (1981) argue that rapists can be distinguished from nonsexual offenders with appropriate phallometric tests, Marshall (in press) argues that the validity of such testing is not proved, and that findings supportive of the testing are a artifact of population differences (i.e., psychiatric vs. correctional) and not reflective of rapists overall. The current study attempts to clarify this issue by testing rapists, child molesters, and mixed offenders (those with both adult and child victims) in a prison setting with both the Barbaree and Quinsey stimulus sets. It was hypothesized that rapists would be found to have more deviant rape indices when tested with the Quinsey stimulus set than with the Barbaree set. However, neither stimulus set distinguished the three groups in terms of the rape indices, whereas the rape index calculated from the Quinsey stimulus set was slightly more deviant than the one calculated from the Barbaree set. However, only 25% of rapists were classified as deviant using a rape index cutoff of 1.0. Thisfinding is discussed in terms of the sexual preference hypothesis.