A new study from Northwestern University concludes that men who describe themselves as bisexual are both genitally and subjectively aroused by watching both films of men having sex with men and of women having sex with women. The same study found that homosexual and heterosexual male participants in the study were not aroused by both.
Medical News Today describes the landmark study as “a scientific U-turn” because in 2005 Northwestern researchers published a report saying that bisexuality did not exist. The new study suggests that previous research was not stringent enough in how it recruited participants.
A research team lead by Allen Rosenthal, a doctoral student in psychology at Northwestern, recruited a racially and ethnically diverse group of men from the greater Chicago area, 35 of whom were bisexual, 31 homosexual and 34 heterosexual.
Unlike previous studies, the recruiting methods for bisexual men in this case focused specifically on men likely to have bisexual erotic interests. Researchers recruited through advertisements in which men sought to have sex with both members of heterosexual couples.
To be eligible for inclusion in the study’s bisexual group, the men “were required to have had at least two sexual partners of each sex and a romantic relationship of at least three months’ duration with at least one person of each sex.”
The researchers showed participants three-minute videos. Two of the videos were neutral, showing landscapes and playing soothing music. Two videos showed two women having sex, and two showed two men having sex. The sexual videos showed both oral and penetrative scenes.
Researchers measured genital sexual arousal by continuously recording changes in the thickness of the penis using a gauge attached to a computer as participants watched the films.
Subjective arousal was measured by self-report on a rating scale, with 0 designating no arousal and 10 meaning extreme arousal.
The results showed that, on average, the bisexual men had distinctly bisexual patterns of both genital and subjective arousal. “Their arousal responses to their less-arousing sex tended to be higher than those of homosexual and heterosexual men,” the researchers concluded.
Rosenthal and his colleagues suggested that while bisexual men appear to have a preference for one sex, they are aroused by both. And for some, their preference could change back and forth over time.