P1: FVK/FLK P2: FMN
Sexual Abuse: A Journal of Research and Treatment [saj] PL103-180 August 1, 2000 9:14 Style ﬁle version Nov. 19th, 1999
Sexual Abuse: A Journal of Research and Treatment, Vol. 12, No. 4, 2000
Sexual Arousal in Rapists as Measured
by Two Stimulus Sets
Some uncertainty exists in the literature regarding the status of phallometric test-
ing 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., psy-
chiatric vs. correctional) and not reﬂective of rapists overall. The current study
attempts to clarifythisissue 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. This ﬁnding is discussed in terms of the sexual preference hypothesis.
KEY WORDS: rapists; phallometric assessment; sexual offending.
Sexualpreference testing with rapists has been conducted since the late 1970s.
To a large extent, the use of this form of testing has been driven by the sexual
preference hypothesis of sexual offending (Lalumiere & Quinsey, 1994), which
states that sexualoffensesare motivated by a sexual preference for coerced sex. The
strong form of this hypothesis states that rapists prefer coercive sexual encounters
to consensual sex, whereas the weak form suggests that rapists become more
aroused to coercive sexual activity than nonrapists. If the strong form of this
hypothesis is true, then rapists should display a sexual preference for rape in
Regional Treatment Centre (Ontario), Ontario, Canada.
To whom correspondence should be addressed at Regional Treatment Centre (Ontario), 555 King St.,
W. P.O. Box 22, Kingston, Ontario, K7L 4V7 Canada.
2000 Plenum Publishing Corporation