I find these studies a bit condescending - even when coming from the British Psychological Society Research Digest. Perhaps I feel that way because I do not believe that most men can be placed cleanly into a hetero, bi, or gay box. Sexual preference for many people falls on a spectrum, and some of us are not attracted to gender as much as we are attracted to people.
Studies such as this one cannot or do not account for criteria outside of sexual arousal. That is a very limited lens through which to view men's choices in relationships.
Jan. 3, 2014
When a man describes himself as bisexual, we usually take this to mean that he has sexual relations with both men and women, and/or that he is attracted to both sexes. However, prior lab research has found that many men who self-identify as bi-sexual are not in fact sexually aroused - in a physical sense - by the opposite sex.
It's important to remember that physical sexual arousal is only one reflection of a person's sexual desires and identity, not the be all and end all. However, this past research suggests that, from a bio-psychological perspective, the label bisexual is used by a diverse group of men. A new study builds on this idea, and finds that a key distinguishing characteristic among bisexual men is their level of sexual curiosity.
Gerulf Rieger and his colleagues conducted two studies with hundreds of men, some of whom were recruited via university adverts, others via websites where men seek sexual partners. The first study used pupil dilation as an index of sexual arousal. The second study used increase in penile circumference as the measure of sexual arousal.
The men, who rated themselves on a sexual orientation sliding scale from strictly homosexual, to bisexual, to strictly heterosexual, watched video clips of attractive male or female models masturbating in the first study, or, in the second study, short videos of two men having sex, or two women having sex. In both studies, the participants also filled out a 10-item questionnaire about their sexual curiosity. Example items included "If I were invited to watch a porn movie, I would accept" and "Sex without love is appealing to me."
On average, men who self-identified as bisexual showed the sexual arousal patterns you might expect, being less aroused than heterosexual men (but more aroused than homosexual men) by videos featuring women, and more aroused than heterosexual men by videos featuring men. This average data conceals the fact that some bisexual men were aroused by both sexes, while others were aroused only by men. The novel finding from this research is that these arousal patterns were correlated with sexual curiosity. Bisexual men on average reported more sexual curiosity than straight or gay men; moreover, among bisexual men only, greater sexual curiosity was linked with more arousal in response to videos featuring women. Bisexual men with low levels of sexual curiosity tended to be aroused only by other men.
Rieger and his colleagues speculate that shared genetic influences likely account for increased sexual curiosity and bisexual physiological arousal, thus explaining why these two characteristics correlate. They also propose that some bisexual men with elevated curiosity may "reattribute" their curiosity-related arousal to sexual stimuli depicting either sex, "thus increasing their sexual arousal and rewarding experiences associated with both men and women." What about the bisexual men who are only aroused by men? Rieger's team suggest that their identity may be in a transitional stage - perhaps they self-identify as bisexual on the basis of past experiences and relationships, or to conform to societal norms.
"The present findings are in line with the notion that a male bisexual identity can be found in a diverse range of men who differ in sexual attitudes and feelings," the researchers said.
Rieger G, Rosenthal AM, Cash BM, Linsenmeier JA, Bailey JM, and Savin-Williams RC (2013). Male bisexual arousal: A matter of curiosity? Biological psychology, 94 (3), 479-89 PMID: 24055219