The validity of phallometric assessment with rapists : Comments on Looman & Marshall

In a recent article Looman and Marshall (2005) questioned the validity of phallometric assessment of rapists based on the results of a study of incarcerated rapists and child molesters. In this commentary we offer (1) a critique of the methods used and conclusions reached by Looman and Marshall and (2) a discussion of important methodological issues relevant to phallometry. We conclude that the correct inference from Looman and Marshall’s study is that rapists, as a group, show a pattern of sexual arousal to audiotaped scenarios of coercive and non-coercive sex that significantly differs from the pattern of groups of non-sex offenders, in agreement with the general literature on this question.