Erections were measured concomitantly with subjective reports of sexual arousal and of pleasantness in six homosexual and six heterosexual males. The stimuli used were two-minute video tapes of four different sexual activities: (1) a single, provocative nude female, (2) two females engaged in lesbian behaviour, (3) heterosexual intercourse, and (4) two males engaged in homosexual behaviour.
The homosexual group responded with significantly greater erections and subjective sexual arousal to the heterosexual and homosexual film than to the single girl or lesbian ones. The heterosexual group's sexual responses to the homosexual films were significantly lower than to the single girl, lesbian, or heterosexual ones, which did not differ. The heterosexuals rated the homosexual cues as unpleasant, whereas homosexuals rated the heterosexual cues as mildly pleasant. The lesbian and homosexual films significantly differentiated the two groups on all three dependent measures. Ten out of 12 subjects showed signficant individual correlation between erection and subjective reports of sexual arousal. Correlation coefficients for the entire group between erection-subjective reports of sexual arousal, erection-pleasantness, and subjective reports of sexual arousal-pleasantness were all significant.