Maximizing the Discriminant Validity of Phallometric Assessment Data

• Published in: Psychological assessment Vol. 4; no. 4; pp. 502 - 511
• Main Authors: Harris, Grant T, Rice, Marnie E, Quinsey, Vernon L, Chaplin, Terry C, Earls, Christopher
• Format: Journal Article
• Language: English
• Published: Washington, DC American Psychological Association 01-12-1992; The Association
• Subjects: Biological and medical sciences; Child Abuse; Discriminant Validity; Human; Measurement; Medical sciences; Methodology. Experimentation; Penis; Perpetrators; Psychiatric Patients; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Rape; Sexual Abuse; Techniques and methods; Test Validity; Human; Sexual behavior disorder; Rape; Discriminant validity; Child sexual abuse; Interindividual comparison; Adult; Male; Plethysmography
• ISSN: 1040-3590; 1939-134X
• DOI: 10.1037/1040-3590.4.4.502

Independent data sets from phallometric assessment studies were analyzed to examine methods of maximizing the discriminant validity of phallometric testing. Community volunteers and non-sex-offender patients were compared with rapists and child molesters recruited primarily from a maximum security psychiatric institution. The results indicated that the discriminant validity of phallometric assessments is enhanced by the use of (a)
z
(rather than raw) scores to compensate for individual differences in responsivity, (b) deviance indexes (computed by calculating the difference in responsivity between deviant and nondeviant stimuli) rather than responses to deviant categories alone, (c) stimuli depicting brutal sexual coercion, and (d) pubescent stimuli for assessing sexual age preferences. Discriminant validity was unimpaired by including subjects with low levels of response. The implications for clinical practice and future research are discussed.