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Jabbour J, Holmes L, Sylva D, Hsu KJ, Semon TL, Rosenthal AM, Safron A, Slettevold E, Watts-Overall TM, Savin-Williams RC, Sylla J, Rieger G, Bailey JM. Robust evidence for bisexual orientation among men. Proc Natl Acad Sci U S A 2020; 117:18369-18377. [PMID: 32690672 PMCID: PMC7414168 DOI: 10.1073/pnas.2003631117] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The question whether some men have a bisexual orientation-that is, whether they are substantially sexually aroused and attracted to both sexes-has remained controversial among both scientists and laypersons. Skeptics believe that male sexual orientation can only be homosexual or heterosexual, and that bisexual identification reflects nonsexual concerns, such as a desire to deemphasize homosexuality. Although most bisexual-identified men report that they are attracted to both men and women, self-report data cannot refute these claims. Patterns of physiological (genital) arousal to male and female erotic stimuli can provide compelling evidence for male sexual orientation. (In contrast, most women provide similar physiological responses to male and female stimuli.) We investigated whether men who self-report bisexual feelings tend to produce bisexual arousal patterns. Prior studies of this issue have been small, used potentially invalid statistical tests, and produced inconsistent findings. We combined nearly all previously published data (from eight previous studies in the United States, United Kingdom, and Canada), yielding a sample of 474 to 588 men (depending on analysis). All participants were cisgender males. Highly robust results showed that bisexual-identified men's genital and subjective arousal patterns were more bisexual than were those who identified as exclusively heterosexual or homosexual. These findings support the view that male sexual orientation contains a range, from heterosexuality, to bisexuality, to homosexuality.
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Affiliation(s)
- Jeremy Jabbour
- Department of Psychology, Northwestern University, Evanston, IL 60208
| | - Luke Holmes
- Department of Psychology, Essex University, Colchester CO4 3SQ, United Kingdom
| | - David Sylva
- Department of Psychiatry, Kaiser Permanente, Los Angeles, CA 90056
| | - Kevin J Hsu
- Department of Psychological and Social Sciences, Pennsylvania State University Abington, Abington, PA 19001
| | - Theodore L Semon
- Department of Psychology, Northwestern University, Evanston, IL 60208
| | - A M Rosenthal
- Department of Psychology, Northwestern University, Evanston, IL 60208
| | - Adam Safron
- Kinsey Institute, Indiana University, Bloomington, IN 47405
| | - Erlend Slettevold
- Department of Psychology, Essex University, Colchester CO4 3SQ, United Kingdom
| | | | | | - John Sylla
- American Institute of Bisexuality, Los Angeles, CA 90014
- University of Chicago Law School, University of Chicago, Chicago, IL 60637
| | - Gerulf Rieger
- Department of Psychology, Essex University, Colchester CO4 3SQ, United Kingdom
| | - J Michael Bailey
- Department of Psychology, Northwestern University, Evanston, IL 60208;
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Safron A, Sylva D, Klimaj V, Rosenthal AM, Bailey JM. Neural Responses to Sexual Stimuli in Heterosexual and Homosexual Men and Women: Men's Responses Are More Specific. Arch Sex Behav 2020; 49:433-445. [PMID: 31399924 DOI: 10.1007/s10508-019-01521-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 05/27/2023]
Abstract
Patterns of genital arousal in response to gendered sexual stimuli (i.e., sexual stimuli presenting members of only one sex at a time) are more predictive of men's than of women's sexual orientations. Additional lines of evidence may shed light on the nature of these differences. We measured neural activation in homosexual and heterosexual men and women using fMRI while they viewed three kinds of gendered sexual stimuli: pictures of nude individuals, pictures of same-sex couples interacting, and videos of individuals self-stimulating. The primary neural region of interest was the ventral striatum (VS), an area of central importance for reward processing. For all three kinds of stimuli and for both VS activation and self-report, men's responses were more closely related to their sexual orientations compared with women's. Furthermore, men showed a much greater tendency to respond more positively to stimuli featuring one sex than to stimuli featuring the other sex, leading to higher correlations among men's responses as well as higher correlations between men's responses and their sexual orientations. Whole-brain analyses identified several other regions showing a similar pattern to the VS, and none showed an opposite pattern. Because fMRI is measured identically in men and women, our results provide the most direct evidence to date that men's sexual arousal patterns are more gender specific than women's.
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Affiliation(s)
- Adam Safron
- Department of Psychology, Northwestern University, Evanston, IL, 60208, USA.
| | | | - Victoria Klimaj
- Department of Psychology, Northwestern University, Evanston, IL, 60208, USA
- Cognitive Science Program & Department of Informatics, Indiana University, Bloomington, IN, USA
| | - A M Rosenthal
- Department of Psychology, Northwestern University, Evanston, IL, 60208, USA
| | - J Michael Bailey
- Department of Psychology, Northwestern University, Evanston, IL, 60208, USA
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Sylva D, Tamayo L, Mosquera-Klinger G, Carvajal J, Pérez J. Eosinophilic gastroenteritis: An unusual presentation of a rare disease. Revista de Gastroenterología de México (English Edition) 2019. [DOI: 10.1016/j.rgmxen.2018.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Sylva D, Tamayo L, Mosquera-Klinger G, Carvajal JJ, Pérez JC. Eosinophilic gastroenteritis: An unusual presentation of a rare disease. Rev Gastroenterol Mex (Engl Ed) 2019; 84:116-118. [PMID: 29555104 DOI: 10.1016/j.rgmx.2018.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/19/2017] [Accepted: 01/25/2018] [Indexed: 06/08/2023]
Affiliation(s)
- D Sylva
- Medicina Interna, Universidad Pontificia Bolivariana, Medellín, Colombia
| | - L Tamayo
- Medicina Interna, Universidad Pontificia Bolivariana, Medellín, Colombia
| | | | - J J Carvajal
- Gastroenterología, Hospital Pablo Tobón Uribe, Medellín, Colombia
| | - J C Pérez
- Patología, Hospital Pablo Tobón Uribe; Universidad Pontificia Bolivariana, Medellín, Colombia
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Safron A, Klimaj V, Sylva D, Rosenthal AM, Li M, Walter M, Bailey JM. Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Women. Sci Rep 2018; 8:673. [PMID: 29330483 PMCID: PMC5766543 DOI: 10.1038/s41598-017-18372-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/11/2017] [Indexed: 11/24/2022] Open
Abstract
We used fMRI to investigate neural correlates of responses to erotic pictures and videos in heterosexual (N = 26), bisexual (N = 26), and homosexual (N = 24) women, ages 25–50. We focused on the ventral striatum, an area of the brain associated with desire, extending previous findings from the sexual psychophysiology literature in which homosexual women had greater category specificity (relative to heterosexual and bisexual women) in their responses to male and female erotic stimuli. We found that homosexual women’s subjective and neural responses reflected greater bias towards female stimuli, compared with bisexual and heterosexual women, whose responses did not significantly differ. These patterns were also suggested by whole brain analyses, with homosexual women showing category-specific activations of greater extents in visual and auditory processing areas. Bisexual women tended to show more mixed patterns, with activations more responsive to female stimuli in sensory processing areas, and activations more responsive to male stimuli in areas associated with social cognition.
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Affiliation(s)
- Adam Safron
- Department of Psychology, Northwestern University, Evanston, Illinois, USA.
| | - Victoria Klimaj
- Department of Psychology, Northwestern University, Evanston, Illinois, USA
| | - David Sylva
- Department of Psychiatry, Kaiser Permanente, Oakland, California, USA
| | - A M Rosenthal
- Department of Psychiatry, Kaiser Permanente, Oakland, California, USA
| | - Meng Li
- Department of Psychiatry, Otto von Guericke University, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Magdeburg, Germany.,Department of Psychiatry, Eberhard Karls University, Tubingen, Germany
| | - Martin Walter
- Department of Psychiatry, Otto von Guericke University, Magdeburg, Germany.,Leibniz Institute for Neurobiology, Magdeburg, Germany.,Department of Psychiatry, Eberhard Karls University, Tubingen, Germany
| | - J Michael Bailey
- Department of Psychology, Northwestern University, Evanston, Illinois, USA
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Safron A, Sylva D, Klimaj V, Rosenthal AM, Li M, Walter M, Bailey JM. Neural Correlates of Sexual Orientation in Heterosexual, Bisexual, and Homosexual Men. Sci Rep 2017; 7:41314. [PMID: 28145518 PMCID: PMC5286516 DOI: 10.1038/srep41314] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/14/2016] [Indexed: 12/30/2022] Open
Abstract
Studies of subjective and genital sexual arousal in monosexual (i.e. heterosexual and homosexual) men have repeatedly found that erotic stimuli depicting men’s preferred sex produce strong responses, whereas erotic stimuli depicting the other sex produce much weaker responses. Inconsistent results have previously been obtained in bisexual men, who have sometimes demonstrated distinctly bisexual responses, but other times demonstrated patterns more similar to those observed in monosexual men. We used fMRI to investigate neural correlates of responses to erotic pictures and videos in heterosexual, bisexual, and homosexual men, ages 25–50. Sixty participants were included in video analyses, and 62 were included in picture analyses. We focused on the ventral striatum (VS), due to its association with incentive motivation. Patterns were consistent with sexual orientation, with heterosexual and homosexual men showing female-favoring and male-favoring responses, respectively. Bisexual men tended to show less differentiation between male and female stimuli. Consistent patterns were observed in the whole brain, including the VS, and also in additional regions such as occipitotemporal, anterior cingulate, and orbitofrontal cortices. This study extends previous findings of gender-specific neural responses in monosexual men, and provides initial evidence for distinct brain activity patterns in bisexual men.
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Affiliation(s)
- Adam Safron
- Department of Psychology, Northwestern University, USA
| | - David Sylva
- Department of Psychology, Northwestern University, USA.,Department of Psychiatry, Kaiser Permanente, USA
| | | | - A M Rosenthal
- Department of Psychology, Northwestern University, USA.,Department of Psychiatry, Kaiser Permanente, USA
| | - Meng Li
- Department of Neurology, Otto von Guericke University Magdeburg, Germany
| | - Martin Walter
- Department of Neurology, Otto von Guericke University Magdeburg, Germany
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Sylva D, Safron A, Rosenthal AM, Reber PJ, Parrish TB, Bailey JM. Neural correlates of sexual arousal in heterosexual and homosexual women and men. Horm Behav 2013; 64:673-84. [PMID: 23958585 DOI: 10.1016/j.yhbeh.2013.08.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 08/09/2013] [Accepted: 08/09/2013] [Indexed: 12/01/2022]
Abstract
Most men have a category-specific pattern of genital and subjective sexual arousal, responding much more strongly to erotic stimuli depicting their preferred sex than to erotic stimuli depicting their nonpreferred sex. In contrast, women tend to have a less specific arousal pattern. To better understand this sex difference, we used neuroimaging to explore its neural correlates. Heterosexual and homosexual women viewed erotic photographs of either men or women. Evoked neural activity was monitored via fMRI and compared with responses to the same stimuli in heterosexual and homosexual men. Overall, a network of limbic (as well as the anterior cingulate) and visual processing regions showed significantly less category-specific activity in women than men. This was primarily driven by weaker overall activations to preferred-sex stimuli in women, though there was also some evidence of stronger limbic activations to nonpreferred-sex stimuli in women. Primary results were similar for heterosexual and homosexual participants. Women did show some evidence of category-specific responses in the visual processing regions, although even in these regions they exhibited less differential activity than men. In the anterior cingulate, a region with high concentrations of sex-hormone receptors, subjective and neural category specificity measures correlated positively for women but negatively for men, suggesting a possible sex difference in the role of the anterior cingulate. Overall, results suggest that men tend to show more differentiated neural responses than do women to erotic photographs of one sex compared to the other sex, though women may not be entirely indifferent to which sex is depicted.
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Affiliation(s)
- David Sylva
- Department of Psychology, Northwestern University, USA
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Rosenthal AM, Sylva D, Safron A, Bailey JM. The male bisexuality debate revisited: some bisexual men have bisexual arousal patterns. Arch Sex Behav 2012; 41:135-47. [PMID: 22194088 DOI: 10.1007/s10508-011-9881-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Self-identified bisexual men report high sexual arousal to both male and female stimuli, but no study to date has compellingly demonstrated that such men have a bisexual pattern of genital arousal. We examined sexual arousal patterns among bisexual men recruited using stringent criteria designed to exclude those who were less likely to have sexual interest in both sexes. Furthermore, we included a bisexual stimulus depicting a man engaged in sex simultaneously with another man and a woman. On average, the bisexual men showed a bisexual arousal pattern, with respect to both self-reported and genital arousal. Additionally, the bisexual men were more aroused by the bisexual stimulus compared with the homosexual and heterosexual men. Some bisexual-identified men have bisexual genital arousal patterns, although it remains unclear how common they are.
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Affiliation(s)
- A M Rosenthal
- Department of Psychology, Northwestern University, 2029 Sheridan Rd., Evanston, IL 60208, USA.
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Rosenthal AM, Sylva D, Safron A, Bailey JM. Sexual arousal patterns of bisexual men revisited. Biol Psychol 2011; 88:112-5. [PMID: 21763395 DOI: 10.1016/j.biopsycho.2011.06.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Revised: 06/08/2011] [Accepted: 06/30/2011] [Indexed: 11/26/2022]
Abstract
Men who identify themselves as bisexual report feeling sexually aroused by both men and women. However, past research has not demonstrated that such men exhibit substantial genital arousal to both male and female erotic stimuli, suggesting that they identify as bisexual for reasons other than their genital arousal pattern. The purpose of the present study was to examine arousal patterns among bisexual men who were recruited using stringent criteria involving sexual and romantic experience with both men and women in order to increase the likelihood of finding a bisexual arousal pattern. Bisexual men in the present study demonstrated bisexual patterns of both subjective and genital arousal. It remains unclear which pattern is most typical of contemporary bisexual men: the present results supporting a bisexual arousal pattern, or previous results not finding one. In either case, understanding men with bisexual arousal patterns could help illuminate the etiology and development of male sexual orientation.
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Affiliation(s)
- A M Rosenthal
- Northwestern University, Department of Psychology, 2029 Sheridan Road, Evanston, IL 60208, USA.
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Sylva D, Rieger G, Linsenmeier JAW, Bailey JM. Concealment of sexual orientation. Arch Sex Behav 2010; 39:141-152. [PMID: 19169803 DOI: 10.1007/s10508-008-9466-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 10/29/2008] [Accepted: 11/22/2008] [Indexed: 05/27/2023]
Abstract
Sex-atypical behaviors may be used to identify a person as homosexual. To shield themselves from prejudice, homosexual people may attempt to conceal these behaviors. It is not clear how effectively they can do so. In Study 1, we asked homosexual participants to conceal their sex-atypical behaviors while talking about the weather. Raters watched videos of the participants and judged the likelihood that each participant was homosexual. Homosexual participants were able to partially conceal signs of their orientation, but they remained distinguishable from heterosexual participants. In Study 2, we tested the ability to conceal signs of one's sexual orientation in a more demanding situation: a mock job interview. In this scenario, homosexual men were even less effective at concealing their orientation. Higher cognitive demands in this new situation may have interfered with their ability to conceal.
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Affiliation(s)
- David Sylva
- Department of Psychology, Northwestern University, Evanston, IL 60208, USA.
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