[Paleopsych] Psychological Science: Sexual Arousal Patterns of Bisexual Men
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Sexual Arousal Patterns of Bisexual Men
Gerulf Rieger1, Meredith L. Chivers2 and J. Michael Bailey1
Volume 16 Issue 8 Page 579 - August 2005
[I can supply the PDF.]
First, the summary from the "Magazine and Journal Reader" feature of the daily
bulletin from the Chronicle of Higher Education, 5.9.9:
Bisexual men generally have a physiological response to one sex or the other,
but not both, even when they report that they are psychologically aroused by
both sexes, three researchers write.
The research was conducted by Gerulf Rieger, a doctoral student in psychology
at Northwestern University, and Meredith L. Chivers, a postdoctoral fellow in
law and mental health at the Center for Addiction and Mental Health in Toronto,
under the supervision of J. Michael Bailey, a Northwestern professor of
psychology whose research has often been controversial in the past (The
Chronicle, December 1, 2004).
The researchers showed images of two men having sex, or of two women, to 33
self-declared homosexual men, 33 bisexual men, and 38 heterosexual men. They
found that the men who described themselves as bisexual generally had a strong
genital arousal to either the male or female sexual images, but not to both,
even though the bisexual men reported that they had felt sexually aroused --
psychologically -- by both sets of images. "Male bisexuality," the authors
write, "appears primarily to represent a style of interpreting or reporting
sexual arousal rather than a distinct pattern of genital sexual arousal." So,
while "in terms of behavior and identity, bisexual men clearly exist,"
skepticism about male bisexuality must "concern claims about bisexual feelings,
that is, strong sexual attraction and arousal to both sexes."
The authors say they undertook the research because, since the beginnings of
the discipline of psychology, controversy has persisted about "whether bisexual
men are substantially sexually aroused by both sexes." Clearly, they note,
bisexual behavior in men exists, because many men certainly have had sex with
both men and women, and, in a 1994 national survey, about 0.8 percent of
American men described themselves as bisexual.
But, the researchers say, their findings provide a new, more complicated
picture of the subject. At the least, they say, "it is reasonable to ask
whether male bisexual behavior reflects sexual arousal to both sexes." The
divergence between genital and reported arousal is "intriguing because measures
of genital and subjective arousal tend to be highly correlated in men," they
say. They also note that earlier research suggests that bisexual men exaggerate
their subjective arousal.
The authors conclude: "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."
There has long been controversy about whether bisexual men are substantially
sexually aroused by both sexes. We investigated genital and self-reported
sexual arousal to male and female sexual stimuli in 30 heterosexual, 33
bisexual, and 38 homosexual men. In general, bisexual men did not have strong
genital arousal to both male and female sexual stimuli. Rather, most bisexual
men appeared homosexual with respect to genital arousal, although some appeared
heterosexual. In contrast, their subjective sexual arousal did conform to a
bisexual pattern. Male bisexuality appears primarily to represent a style of
interpreting or reporting sexual arousal rather than a distinct pattern of
genital sexual arousal.
Although bisexual behavior is not uncommon in men, there has long been
skepticism that it is motivated by strong sexual arousal and attraction to both
sexes. For example, the case studies of Krafft-Ebing (1886) suggest that most
men with bisexual activity have sex with women because of social pressure but
have sexual attraction exclusively or almost exclusively to men (Cases 127,
128, 135 [-] 153, and 167). Hirschfeld (1914/2001, pp. 197 [-] 215) speculated
that most self-identified bisexual men are either heterosexual or homosexual
and that men with substantial bisexual attractions are rare. Freund, who was a
pioneer in measuring male genital arousal, wrote that, after assessing genital
arousal in hundreds of men, he never found convincing evidence that bisexual
arousal patterns exist (1974, p. 39). The existence of male bisexual attraction
and arousal remains controversial and poorly understood (Fox, 2000; MacDonald,
2000; Zinik, 2000).
BISEXUALITY: BEHAVIOR, IDENTITY, AND AROUSAL
Sexual orientation refers to the degree of sexual attraction, fantasy, and
arousal that one experiences for members of the opposite sex, the same sex, or
both. Men's self-reported sexual orientation tends to be bimodal, with the
large majority reporting exclusive sexual attraction to women and a minority
reporting exclusive or near-exclusive attraction to men; the number of men who
report substantial sexual attraction to both men and women is even smaller
(Bailey, Dunne, & Martin, 2000; Diamond, 1993; Laumann, Gagnon, Michael, &
Patterns of sexual behavior (i.e., sexual contact with men or women) are
certainly influenced by sexual orientation, but may diverge from it for various
reasons, including limitations in opportunity (e.g., imprisoned men without
access to women), stigmatization (typically against homosexuality), or material
reasons, as in the case of prostitution (Gagnon, Greenblat, & Kimmel, 1999 ).
Unquestionably, during the course of their lives, some men have sex with both
men and women. One survey of homosexual men found that about 69% had also been
sexually active with women (Bell, Weinberg, & Hammersmith, 1981). Furthermore,
some imprisoned men say that they are heterosexual even though they engage in
homosexual sex (Kirkham, 2000 ). Given these discrepancies between reported
sexual orientation and sexual behavior in some men, it is reasonable to ask
whether male bisexual behavior reflects sexual arousal to both sexes.
Sexual identity refers to labels, including "homosexual,""heterosexual," or
"bisexual," that individuals often give themselves (Sell, 1997). In a national
survey, 0.8% of American men identified as bisexual (Laumann et al., 1994 ).
There may be varied reasons why some men adopt a bisexual identity. For
example, they may have intense sexual attraction to both men and women, or they
might have sex partners of both sexes. Furthermore, men who adopt a homosexual
identity might go through a stage in which they consider themselves bisexual.
In one study, up to 40% of homosexual men defined themselves as bisexual before
adopting a gay identity (Lever, 1994). In another study, most bisexual men
shifted over time toward homosexuality; however, a small number shifted toward
heterosexuality (Stokes, Damon, & McKirnan, 1997 ). This suggests that some
bisexually identified men might have homosexual feelings (i.e., substantial
attraction and arousal only to men), whereas others might have heterosexual
feelings (i.e., substantial attraction and arousal only to women).
In terms of behavior and identity, bisexual men clearly exist. Skepticism about
male bisexuality must therefore concern claims about bisexual feelings, that
is, strong sexual attraction and arousal to both sexes. The primary
methodological challenge for investigating this issue is to employ a measure of
sexual feelings that does not depend on self-report. At present, this is
possible only for genital sexual arousal.
MEASURING MALE SEXUAL AROUSAL
Male genital arousal can be measured using a circumferential strain gauge that
reflects the changes in penile girth during erection (Janssen, 2002 ).
Homosexual men show substantially more genital arousal to sexual stimuli
depicting men (male sexual stimuli) than to those depicting women (female
sexual stimuli); heterosexual men have the opposite pattern ( Chivers, Rieger,
Latty, & Bailey, 2004; Freund, 1963; Freund, Watson, & Rienzo, 1989; Sakheim,
Barlow, Beck, & Abrahamson, 1985). Subjective sexual arousal is measured by
self-report and is typically highly correlated with genital arousal in men
(Sakheim et al., 1985 ). However, when self-report is suspect, genital arousal
may provide a more valid measure. For example, genital arousal to stimuli
depicting children is an effective method of assessing pedophilia, even among
men who deny attraction to children (Blanchard, Klassen, Dickey, Kuban, & Blak,
Few studies have investigated genital arousal among bisexual men. One study
(McConaghy & Blaszczynski, 1991 ) measured genital sexual arousal to slides of
nude men and women in 20 men with problematic sexual preferences (e.g.,
pedophilia, exhibitionism, bondage, and fetishism). The authors reported that
the bisexual-identified men among their sample showed bisexual arousal.
However, because of the heterogeneous study sample, and because the authors did
not use rigorous statistical analyses to distinguish bisexual arousal from
heterosexual or homosexual arousal, the study does not definitively demonstrate
that bisexual men have bisexual arousal. Another study compared the genital
arousal to male and female stimuli of 10 heterosexual, 10 bisexual, and 10
homosexual men (Tollison, Adams, & Tollison, 1979 ). Bisexual-identified men
were indistinguishable from homosexual-identified men in their patterns of
genital arousal. However, the group sizes in this study were relatively small,
and thus the study may have lacked power to detect differences between the two
THE CURRENT STUDY
We recruited self-identified heterosexual, bisexual, and homosexual men and
assessed their genital and self-reported sexual arousal to male and female
sexual stimuli. Our analyses investigated three hypotheses:
Bisexual men are substantially aroused by both male and female stimuli.
Bisexual men, like homosexual men, are much more aroused by male than by female
Bisexual men show a mixture of homosexual and heterosexual patterns of sexual
arousal, with some having much more arousal to male stimuli and others having
much more arousal to female stimuli.
Note that these hypotheses are not mutually exclusive.
We advertised in gay-oriented magazines and an alternative newspaper in Chicago
for "heterosexual,""bisexual," and "gay" men for a paid study of sexual
arousal. Men who called the lab were asked about their sexual attraction toward
men and women, so that their sexual orientation could be determined (see
Measures and Procedure). Participants included 30 heterosexual men, 33 bisexual
men, and 38 homosexual men, categorized on the basis of their answers to those
questions. We also asked men to describe their sexual identity as straight,
bisexual, or gay. Sexual attraction and sexual identity (converted to a numeric
3-point scale) were highly correlated, r= .95. Mean ages (standard deviations
in parentheses) were 31.6 (5.9), 31.2 (5.4), and 30.6 (5.8), for the
heterosexual, bisexual, and homosexual men, respectively. The percentage of
Caucasian participants was 49.3, and this percentage did not vary significantly
across groups. The heterosexual and homosexual participants were included in an
earlier study (Chivers et al., 2004).
Measures and Procedure
The measures and procedure of this study were identical to those of our earlier
study (Chivers et al., 2004), and the report of that study provides more
Sexual orientation was assessed via self-report using the Kinsey Sexual
Attraction Scale (Kinsey, Pomeroy, & Martin, 1948 ). Participants provided
separate Kinsey ratings for their sexual orientation during the past year and
during adulthood. The mean of these two ratings was used in all analyses.
"Heterosexual men" were defined as men with Kinsey Attraction scores less than
or equal to 1, "bisexual men" had Kinsey Attraction scores greater than 1 and
less than 5, and "homosexual men" had Kinsey scores greater than or equal to 5.
Participants viewed an 11-min, neutral, relaxing film (e.g., landscapes),
followed by several 2-min sexual films, and another neutral film. Two of the
sexual films depicted two men having sex with each other, and two of the films
depicted two women having sex with each other.
Genital arousal was assessed using a penile mercury-in-rubber gauge measuring
circumference changes during erection (Janssen, 2002 ). Participants indicated
subjective arousal by moving a lever forward to indicate increasing arousal and
backward to indicate decreasing arousal.
Because not all men become sufficiently sexually aroused for valid assessment,
it is important to exclude nonresponders (Seto et al., 2001 ). We excluded
participants whose genital response to any sexual stimuli was less than a 2-mm
increase in penile circumference and whose subjective response was less than
5%, compared with response to neutral stimuli. The final sample contained 21
heterosexual, 22 bisexual, and 25 homosexual men with sufficient genital
arousal for analyses and 24 heterosexual, 24 bisexual, and 31 homosexual men
with sufficient subjective arousal.
For each combination of participant and film clip, we computed mean genital and
subjective arousal. Next, for each participant, we standardized genital and
subjective arousal across film clips. Finally, we averaged the standardized
genital arousal across female sexual stimuli in order to compute mean genital
arousal to female stimuli; analogous calculations yielded mean genital arousal
to male sexual stimuli and to the neutral stimulus, and mean subjective arousal
to female and to male sexual stimuli, and to the neutral stimulus. Whenever
arousal to sexual stimuli was used in analyses, we first subtracted arousal to
the neutral stimulus.
Our first analyses examined whether men who report bisexual feelings have a
bisexual arousal pattern. Men with strong bisexual arousal need not have
precisely the same degree of arousal to both male and female stimuli. However,
on average, their arousal to both male and female stimuli should be
substantial. Furthermore, their arousal to male stimuli should exceed that of
heterosexual men, and their arousal to female stimuli should exceed that of
homosexual men. The hypothesis that bisexual men have bisexual arousal patterns
thus implies a negative quadratic relation between self-reported
sexual-attraction score (Kinsey score) and sexual arousal to the less arousing
sex (Fig. 1a).
Figure 1b shows that the predicted curvilinear relation did not occur for
genital arousal. The quadratic model was nonsignificant, p= .68, [beta] = [-]
.05, [Delta] R2 = .00. In contrast, bisexual men's subjective arousal did show
the predicted curvilinearity; the negative quadratic relation was significant,
p< .0001, [beta] = [-] .56, [Delta] R2= .29 (Fig. 1c ). Thus, we found no
indication of a distinctly bisexual pattern of genital sexual arousal among
bisexual men, although they did report a distinctly bisexual pattern of
subjective sexual arousal.
Notably, on average all men, regardless of their sexual orientation, showed
significantly more genital arousal to their less arousing sex than they did to
neutral stimuli; the 95% confidence interval for the curve in Figure 1b is
above zero. However, the figure also shows that arousal to the less arousing
sex was markedly lower than arousal to the more arousing sex.
Our next analyses examined whether bisexual men tend to have homosexual arousal
patterns, with greater arousal to male than to female stimuli. We computed a
male-female contrast by subtracting each participant's arousal to female
stimuli from his arousal to male stimuli; thus, higher scores indicate more
arousal to men. If most bisexual men are primarily aroused by male stimuli,
then there should be a negative quadratic relation between the participants'
Kinsey scores and their arousal difference scores (Fig. 2a).
With respect to genital arousal, the quadratic relation was significant (Fig.
2b)1; bisexual men were more aroused by male stimuli than by female stimuli, p<
.01, [beta] = [-] .21, [Delta] R2= .04. The analogous quadratic relation for
subjective arousal was also significant (Fig. 2c), p< .01, [beta] = [-] .16,
[Delta] R2= .02; bisexual men reported greater arousal to male than female
Although these analyses suggest that bisexual men tend to show more arousal to
male than to female sexual stimuli, inspection of Figure 2b suggests that not
all do. Several men with Kinsey Attraction scores in the bisexual range tended
to show most genital arousal to female sexual stimuli (i.e., their arousal
contrast scores were negative). To investigate the hypothesis that bisexual men
include a mixture of men with either homosexual or heterosexual arousal
patterns, we computed the absolute residuals from the regressions shown in
Figure 2 . If this hypothesis is correct, then the residuals should be largest
within the bisexual range of the Kinsey scale, and the relation between these
residuals and Kinsey scores should be negative quadratic (Fig. 3a).
This quadratic relation was significant for both genital arousal (Fig. 3b), p<
.05, [beta] = [-] .25, [Delta] R2= .04, and subjective arousal (Fig. 3c), p<
.01, [beta] = [-] .33, [Delta] R2 = .10. These results suggest that the
bisexual men whose arousal patterns were least similar to those of homosexual
men tended to have arousal patterns similar to those of heterosexual men.
Men who reported bisexual feelings did not show any evidence of a distinctively
bisexual pattern of genital arousal. One must be cautious, of course, in
drawing conclusions from negative results. However, the crucial analysis of
arousal to the less arousing sex did not provide even a hint of the expected
effect. On average, both homosexual and heterosexual men had much higher
arousal to one sex than to the other, and this was equally true of bisexual
To be sure, most men were more genitally aroused to stimuli depicting their
less arousing sex than to neutral stimuli. This finding contradicts some prior
research in which men's arousal to their less preferred sex was comparable to
their response to a neutral stimulus (Freund, 1974; Freund, Langevin, Cibiri, &
Zajac, 1973 ). This suggests that most men may possess a certain capacity for
bisexual arousal, although the magnitude of this arousal is quite modest.
In contrast to bisexual men's genital arousal, their subjective arousal did
show the expected pattern. The divergence between results for genital and
subjective arousal is intriguing, because measures of genital and subjective
arousal tend to be highly correlated in men (Sakheim et al., 1985 ). For
example, across all our participants, the correlation between the genital and
subjective male-female contrasts was .85. These results suggest that with
respect to their less preferred sex, either bisexual men's subjective arousal
has been exaggerated or their genital arousal has been suppressed. An earlier
study suggests that the former explanation is more likely. In this study,
bisexual men, compared with heterosexual and homosexual men, had greater
discrepancies between their objectively measured and subjectively estimated
genital arousal, and this was primarily due to an overestimation of their
erections to female stimuli (Tollison et al., 1979 ). This issue may be
clarified by studies using emerging technology identifying brain activation
patterns associated with sexual arousal (Barch et al., 2003; Hamann, Herman,
Nolan, & Wallen, 2004 ). In principle, such activation patterns could have
higher validity than penile erection or self-reported arousal as a measure of
sexual arousal. In any case, our results suggest that male bisexuality is not
simply the sum of, or the intermediate between, heterosexual and homosexual
orientation. Indeed, 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
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1The curvilinear effect remained even after excluding 3 homosexual men who
showed more arousal to women than to men, p= .01, [beta] = [-] .17, [Delta] R2=
(Received 8/27/04; Revision accepted 11/10/04)
1Northwestern University and 2Centre for Addiction and Mental Health, Toronto,
Correspondence Address correspondence to Gerulf Rieger, Psychology Department,
Northwestern University, 2029 Sheridan Rd., Swift Hall #102, Evanston, IL
60208; e-mail: gerulf at northwestern.edu.
Fig. 1. Sexual arousal as a function of sexual orientation. In each panel, the
curve labeled "1" pres...
Fig. 2. Male-female arousal contrast (arousal to male sexual stimuli minus
arousal to female sexual s...
Fig. 3. Absolute residuals from the regressions of Figure 2 as a function of
sexual orientation. The ...
To cite this article
Rieger, Gerulf, Chivers, Meredith L. & Bailey, J. Michael (2005)
Sexual Arousal Patterns of Bisexual Men.
Psychological Science 16 (8), 579-584.
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