

(In contrast, most women provide similar physiological responses to male and female stimuli.) We investigated whether men who self-report bisexual feelings tend to produce bisexual arousal patterns.

Patterns of physiological (genital) arousal to male and female erotic stimuli can provide compelling evidence for male sexual orientation. Although most bisexual-identified men report that they are attracted to both men and women, self-report data cannot refute these claims.

Skeptics believe that male sexual orientation can only be homosexual or heterosexual, and that bisexual identification reflects nonsexual concerns, such as a desire to deemphasize homosexuality. They would add: "The histories which have been available in the present study make it apparent that the heterosexuality or homosexuality of many individuals is not an all-or-none proposition.The question whether some men have a bisexual orientation-that is, whether they are substantially sexually aroused and attracted to both sexes-has remained controversial among both scientists and laypersons. "It is generally thought that these qualities make a homosexual person obvious and recognizable to any one who has a sufficient understanding of such matters."

"It is quite generally believed that one’s preference for a sexual partner of one or the other sex is correlated with various physical and mental qualities, and with the total personality which makes a homosexual male or female physically, psychically, and perhaps spiritually distinct from a heterosexual individual," the co-authors wrote.
