In an unusual scientific about-face, researchers at Northwestern University have found evidence that at least some men who identify themselves as bisexual are, in fact, sexually aroused by both women and men.
The finding is not likely to surprise bisexuals, who have long asserted that attraction often is not limited to one sex. But for many years the question of bisexuality has bedeviled scientists. A widely publicized study published in 2005, also by researchers at Northwestern, reported that “with respect to sexual arousal and attraction, it remains to be shown that male bisexuality exists.”
That conclusion outraged bisexual men and women, who said it appeared to support a stereotype of bisexual men as closeted homosexuals.
In the new study, published online in the journal Biological Psychology, the researchers relied on more stringent criteria for selecting participants. To improve their chances of finding men aroused by women as well as men, the researchers recruited subjects from online venues specifically catering to bisexuals.
They also required participants to have had sexual experiences with at least two people of each sex and a romantic relationship of at least three months with at least one person of each sex.
Men in the 2005 study, on the other hand, were recruited through advertisements in gay-oriented and alternative publications and were identified as heterosexual, bisexual or homosexual based on responses to a standard questionnaire.
In both studies, men watched videos of male and female same-sex intimacy while genital sensors monitored their erectile responses. While the first study reported that the bisexuals generally resembled homosexuals in their responses, the new one finds that bisexual men responded to both the male and female videos, while gay and straight men in the study did not.
Both studies also found that bisexuals reported subjective arousal to both sexes, notwithstanding their genital responses. “Someone who is bisexual might say, ‘Well, duh!’” said Allen Rosenthal, the lead author of the new Northwestern study and a doctoral student in psychology at the university. “But this will be validating to a lot of bisexual men who had heard about the earlier work and felt that scientists weren’t getting them.”
The Northwestern study is the second one published this year to report a distinctive pattern of sexual arousal among bisexual men.
In March, a study in Archives of Sexual Behavior reported the results of a different approach to the question. As in the Northwestern study, the researchers showed participants erotic videos of two men and two women and monitored genital as well as subjective arousal. But they also included scenes of a man having sex with both a woman and another man, on the theory that these might appeal to bisexual men.
The researchers — Jerome Cerny, a retired psychology professor at Indiana State University, and Erick Janssen, a senior scientist at the Kinsey Institute — found that bisexual men were more likely than heterosexuals or gay men to experience both genital and subjective arousal while watching these videos.
Dr. Lisa Diamond, a psychology professor at the University of Utah and an expert on sexual orientation, said that the two new studies, taken together, represented a significant step toward demonstrating that bisexual men do have specific arousal patterns.
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