Skepticism about the existence of people attracted to both men and women has come from heterosexuals as well as gays and lesbians. Even within the scientific community there has been debate about the existence and meaning of bisexuality. No one seems to argue with the reality that some people have sex with both men and women. The skepticism has centered on if that behavior is motivated by a strong sexual attraction to both sexes.
This debate recently flared up around the publication of an article by Rieger, Chivers, and Bailey that compared the genital and self-reported sexual arousal patterns of men who identified as heterosexual, bisexual, and gay. Men came into a private room in a lab and were shown several films that either included two men having sex with each other or two women having sex with each other. Genital arousal patterns were measured using a gauge that measures changes in the circumference of the penis as it becomes erect. This is also called a penile plethysmograph (shown at left). Participants also self-reported their sexual arousal by moving a lever backwards and forwards to show increasing or decreasing arousal.
After analyzing the data the authors found different patterns between the gay, bisexual, and heterosexual men. The gay identified men had strong self-reported and physiological arousal to the videos to two men having sex. The heterosexual men showed the opposite pattern of arousal to the videos of two women having sex. The bisexual men also tended to show a physiological arousal that was stronger for videos with women or men. On average the bisexual men tended to be more aroused by male than female stimuli. But it is very important to point out that not all bisexual men showed this pattern. Some of the bisexually identified men showed more arousal to the female videos. In contrast to the physical measure of arousal, the bisexual men tended to show more equal self-reported arousal to both the male and female videos. The authors of the study reached the controversial conclusion that "with respect to sexual arousal and attraction, it remains to be shown that male bisexuality exists. Thus future research should also explore nonsexual reasons why some men might prefer a bisexual identity to a homosexual or heterosexual identity."
Some researchers have criticized the conclusions drawn from the study by saying that the measures of sexual arousal were too crude to capture the richness of sexual attraction that includes more than genital and self-reported arousal while watching 2 minute video clips. In a New York Times article, Dr. Gilbert Herdt, director of the National Sexuality Resource Center in San Francisco, was quoted as saying, "To claim on the basis of this study that there's no such thing as male bisexuality is overstepping, it seems to me."
To help understand differences in sexual attractions and bisexuality in men and women, I recorded a video interview with Dr. Brian Dodge at a recent conference. As a Research Scientist and Associate Director of the Indiana University Center for Sexual Health Promotion. He answers my question, "what is bisexuality?" One point that he makes that is relevant to the scientific debate stemming from the study mentioned above is that bisexuality may incorporate more than just sexual attractions and arousals, but also include emotional attractions to men and women. He goes on to talk about stereotypes about bisexuality and nom-monogamy and answer other important questions about bisexuality.
You can watch the by clicking the play button or by going to YouTube.
Dr. Mustanski is the Director of the IMPACT LGBT Health and Development Program at the University of Illinois at Chicago. You can follow his work on the program's webpage. You can follow the Sexual Continuum blog by becoming a fan on Facebook.
Photo of the mercury-in-rubber penile plethysmograph courtesy of Dr. Jorge Ponseti, posted at http://www.indiana.edu/~sexlab/ei-pp.html