Voluntary control of penile tumescence among homosexual and heterosexual subjects.

Voluntary control of erectile responses represents a major threat to the validity of penile plethysmography. This study was designed to determine whether individuals can mimic a sexual orientation that differs from their actual sexual orientation. Since the presumed mechanism underlying voluntary control of penile tumescence involves a shift in attentional focus, a recall test was employed to assess the relationship between the ability to influence erectile responses and recall of critical test stimuli. Homosexual and heterosexual subjects were exposed to sexual materials under standard and "faking" instructions. The faking instructions consisted of asking subjects to suppress erectile responses to preferred stimuli and to enhance penile tumescence in the presence of nonpreferred stimuli. Across groups, results revealed some degree of suppression of erections but no significant enhancement of erections. Self-reported cognitive arousal under both conditions was consistent with erectile data. However, subjects' perceived control over erectile responses tended to be greater than their actual performance. No significant differences in recall were obtained. The recall procedure appears to interfere with subjects' ability to control erectile responses. Implications for clinical applications of penile plethysmography are summarized with suggestions for future research.