An examiner met individually with each subject and instructed him on advancing and rating the slides. The subject viewed the slides in a dimly lit, quiet cubicle. After a practice session, the subject completed the VRT in private. After viewing each slide, participants rated each slide on a scale from 1 (extremely sexually repulsive) to 7 (extremely sexually interesting). A computer recorded the amount of time a subject viewed and rated each slide. Data from the second viewing time were utilized by Abel Screening, Inc. to compute the z-scores. These were provided to the investigator in graph form, with a score for self-reported interest. Per manufacturer’s instructions, the Abel “rule of thirds” was utilized to define the predominant sexual preference. Because of the large number of sexual preference choices generated by the Abel method, a modification was adopted. For this study, predominant sexual preference was defined as a relative visual reaction time z-score  1 SD. The number of times each stimulus was  1 SD was recorded. If only one or none of the SDs were  1, the two highest scores were recorded. This modification resulted in an objective measure of only those selections that stimulated the longest VRT (Table III).