Researchers Revisit Male Bisexuality — and Draw Critics

Some 2 percent of men in the U.S. identify as bisexual. But, for decades, some sexuality researchers have questioned whether true bisexual orientation exists in men.

In 2005, J. Michael Bailey, a sexuality researcher at Northwestern University, and two colleagues showed men who identify as bisexual brief pornographic clips featuring men or women, while measuring their subjects’ self-reported arousal and change in penis circumference. The results, when compared to men who identified as straight or gay, led them to conclude that the men identifying as bisexual did not actually have “strong genital arousal to both male and female sexual stimuli.” This was in contrast to work on sexual arousal in women, which showed that they — whether identifying as straight or gay — were physically aroused by both male and female stimuli.

A New York Times headline covering Bailey’s 2005 study on men declared: “Straight, Gay, or Lying? Bisexuality Revisited.”

But the paper also spurred more research into the subject — some of which has now led Bailey to revise his conclusions. In a paper published last month in the Proceedings of the National Academy of Sciences (PNAS), Bailey and 12 colleagues reanalyzed data from eight previously published studies of bisexual-identified men, including the 2005 paper. The new review finds that men who reported attraction to both men and women do in fact show genital arousal towards both male and female stimuli. The data, the authors conclude, offers “robust evidence for bisexual orientation among men.”

The PNAS study has drawn positive coverage and received praise from some activists, who see it as valuable confirmation for an often-marginalized sexual identity. But it has also received backlash from other scientists and many bisexual people, some of whom argue that in attempting to prove, based on genital arousal, that bisexuality exists, researchers are discounting bisexual people’s lived experiences. It has also reignited a broader debate over the ethics of human sexuality research — and about what role, if any, scientists should play in validating the experiences of queer people.

For his part, Bailey defended the research, arguing that the phenomenon of bisexuality ought to be studied in order to be understood. “If we let the possibility that somebody is offended — particularly some identity group is offended — guide us in terms of what research we do,” he said, “we just won’t learn things, including about very interesting and important topics.”

John Sylla, an co-author on the paper and the president of the American Institute of Bisexuality (AIB), a private foundation that funded some of the research covered in the re-analysis, said it was simply part of the process of science self-correcting. “It’s frankly one more step towards making bisexuality cool, assumed, and normal,” Sylla told Undark.

But others don’t find the study so benign. “The word that immediately sprang to my mind was condescending — and unnecessary,” said Greg Albery, a disease ecologist at Georgetown University who identifies as bisexual.

“I worry most about establishing the premise that in order for people’s sexualities or identities of any sort to be valid,” he added, “they need to be first scientifically proven.”

For years, sex researchers have held differing opinions those who report strong attraction to people of multiple genders. “Males do not represent two discrete populations, heterosexual and homosexual,” the pioneering sex researcher Alfred Kinsey wrote in 1948. “The world is not to be divided into sheep and goats.”

But some researchers questioned whether bisexual men actually had substantial arousal to both male and female erotic stimuli, hypothesizing that bisexual-identified men were actually homosexual, and only claiming to be bisexual because it hewed closer to heterosexuality and, as a result, felt more socially acceptable. Starting in the 1970s, some researchers tried to bring concrete data to the question through a technique called plethysmography, which measures the change in volume or circumference of an organ or other part of the body.

In penile plethysmography, researchers typically use a circular strain gauge — essentially a small circle of rubber tubing, filled with a liquid conductor and connected to sensors — to measure changes in circumference of the penis. In the studies included in the new PNAS review, researchers instructed men on how to hook their penises up to a plethysmography device, then showed them pornographic videos and measured their genital arousal.

Critics of this method argue that it produces a highly artificial scenario: A participant is in an unfamiliar setting, with a strain gauge fastened around his penis, watching brief clips of porn that have been selected by someone else. They question how much this setup can tell researchers about real-world sexuality.

“It’s frankly one more step towards making bisexuality cool, assumed, and normal,” Sylla said.

Penile plethysmography also has a fraught history. Immigration officials in some countries have used it to test if gay-identified asylum seekers really were gay, and it’s still used by some U.S. courts to assess sex offenders’ attraction to children.

Nevertheless, some researchers have argued that the technique is useful for quantifying sexual arousal. And some early attempts to apply it to bisexual men suggested that their genital arousal diverged from their reported experiences. In Bailey’s influential 2005 study, for example, even though men reported being aroused by both male and female stimuli, their genitals seemed to prefer one or the other.

The study included just 33 men who identified as bisexual, and among these, only 22 produced sufficient arousal to any erotic stimuli to be included in the final result. Later studies would produce conflicting findings, and Lauren Beach, a research assistant professor studying stigma and LGBT health at Northwestern University and a founding member of the Bisexual Research Collective on Health, said that in making such a strong conclusion from a study with so few participants, the 2005 analysis amounted to “shoddy science.”

By drawing on a bigger dataset than in previous research, the new PNAS paper aimed to offer more definitive evidence than those individual studies. Nevertheless, it almost immediately ran into criticism from other researchers. In particular, many argued that the paper blurred the lines between genital arousal and sexual orientation — a concept that, many experts say, is more complex than a physical response. Sexual orientation “has multiple facets,” said Corey Flanders, an assistant professor at Mount Holyoke College who studies health disparities in gender and sexual minority individuals. “It’s not just this physiological arousal measured by pupil dilation or genital arousal,” she said.

“Sexual orientation is a really broad and rich construct,” she added.

Jeremy Jabbour, a Ph.D. student in clinical psychology at Northwestern University and a lead author on the paper, said that he sympathizes with those criticisms. Jabbour, who himself identifies as queer, said that there was some disagreement between himself and the more senior authors about how the data should be presented. “There was a little back-and-forth about how we wanted to frame the paper, what the title should be, what kind of terminology we should use,” he told Undark. “I lost that battle.”

The use of the term “sexual orientation” in the paper, Jabbour said, was meant only to indicate patterns of genital arousal, and he thought it would be “very clear that we’re not talking about sexual orientation as a broader phenomenon.” But, he acknowledged, “that very clearly wasn’t the case.”

Bailey, who is no stranger to controversy, defended the team’s choice of terminology. “If a man produces a clear arousal pattern in our procedure, I trust that result more than I trust what that man says about his feelings,” he said, adding that he believes “that for men, the best understanding of sexual orientation is a sexual arousal pattern.”

To explain the rationale for physiological studies of arousal in bisexual men, Bailey invoked an old saying about bisexual men. “My gay friends, some of them, would say that you’re either gay, straight, or lying,” Bailey said. “I think that they often said this because they themselves went through a stage where they said they were bisexual, and they weren’t really.”

Other sex researchers, however, questioned whether measuring arousal can be used to confirm a person’s sexual orientation, noting that sexual orientation is complex and multidimensional. “We know that peoples’ attractions aren’t always conventional, and different things pique different peoples’ interests,” said Brian Feinstein, another sexuality researcher at Northwestern.

Beach, who uses they/them pronouns, agreed. “Who decides what is arousing?” they asked. “Like ‘you must be turned on by this video and if you’re not, you must be gay?’”

The backlash reflects a long history of debate over the role that scientific research should play in advocacy for queer communities.

Historically, advocates have drawn on the idea that an LGBT identity is innate to argue for marriage equality and against conversion therapies that claim to change sexual orientation — and that, experts say, are both fraudulent and deeply harmful. Surveys have suggested that people who believe sexual orientation is biologically determined are more supportive of gay rights than those who believe it is a choice.

Sylla and the American Institute of Bisexuality, which was founded by the human sexuality researcher Fritz Klein in 1998, have embraced that approach. The foundation focuses on research, education, and community building, and it runs websites such as and Queer Majority. Sylla first reached out to Bailey after the 2005 study, and he told Bailey that AIB might be interested in funding further research. Six of the eight studies in the new PNAS analysis received funding from the organization.

“Who decides what is arousing?,”Beach asked. “Like ‘you must be turned on by this video and if you’re not, you must be gay?’”

“Sexuality has had such a bumpy ride with politics and morality,” Sylla said. “And some people thinking that orientation is a choice. It can perhaps be helpful to show people non-judgmental evidence that, in terms of science, people just have different appetites.”

In recent years, though, as LGBT people have gained wider rights in American society, more advocates and researchers have questioned why they need scientific evidence to validate their experiences of attraction and arousal. “I can understand the desire for AIB and for other bisexual people broadly to want to correct that narrative, to be like, ‘Oh, this research exists and I think it’s wrong, and I have the means and resources to try to step in and help generate a different narrative that more accurately reflects my existence, my truth,’” said Flanders of the AIB response to the 2005 study.

But Flanders is skeptical of the value that the research has for the bisexual community in 2020. “I think I feel similarly to a lot of other bisexual people and bisexual activists around the idea of: Is this a question that we actually need to ask in this way?” she said. “Can’t we take people’s word for it that an individual who identifies as bisexual is bisexual, and therefore bisexual men exist? It’s pretty simple and straightforward.”

Even though the study concluded that male bisexuality existed, “just by deeming it a necessary question, you’re immediately undermining the status of a massive group of people,” said Albery, the Georgetown researcher. Increasingly, Beach, Flanders, and Feinstein all said, human sexuality researchers take it as an accepted premise that bisexuality is a sexual orientation.

And, Beach argues, research questions that seem to doubt bisexual experience can themselves be harmful. “There are psychological studies that show denial and erasure of bisexual people’s sexual orientation,” they said, “causes direct psychological harm to bisexual people.”

“Can’t we take people’s word for it that an individual who identifies as bisexual is bisexual, and therefore bisexual men exist? It’s pretty simple and straightforward.”

Bailey, who has faced such criticisms before, continues to defend his research. “I inhabit a different world. And my world is the world that knowledge is good,” he said.

His research, he added, “has done a lot to de-stigmatize various groups over the years.” Groups expressing offense, he argues, have harmed the field: “I’ve been an academic since 1989. This is the worst time I have ever experienced as a scientist.”

Other researchers think the picture is less bleak. In a follow-up email to Undark, Flanders argued that, when people express offense at research, it can actually make science better, by pushing scientists to account for “a greater array of experience and perspectives.” Some sexuality research, she argued, seems mostly concerned with questioning whether some fundamental part of a person’s identity is real — an approach, she said, that forces queer people “to engage in an academic debate about their personhood.”

Instead, Flanders said scientists should question traditional assumptions about sexuality and center the lived experiences of marginalized people. “I do not believe that people being offended has made the world worse,” she wrote. “I believe people speaking out against systems of oppression is, again, essential to scientific progress.” 

Hannah Thomasy is a freelance science writer splitting time between Toronto and Seattle. Her work has appeared in Hakai Magazine, OneZero, and NPR.