xa,b
Neu
, In
Jan
12
of studies using such stimuli and assessing neural, subjective,
and genital endpoints. The current study addressed the
(Duchowski, 2002; Josephson and Holmes, 2002). The order
and duration of fixations on specific features of a stimulus vary
with the interest of the subject (Rizzo et al., 1987; Isaacowitz,
2006). Individual differences in scan patterns reflect subject-
Hormones and Behavior 51 (Experimental studies generally agree that men and women
respond differently to visual sexual stimuli (e.g., Laan et al.,
1994; Murnen and Stockton, 1997; Schmidt, 1975; Steinman et
al., 1981). However, it is unknown to what extent these
differences reflect variation in the central cognitive processing
of the stimuli, including memory, attention, and emotion. It is
often assumed that when looking at a stimulus, such as a picture
of sexual intercourse, that men and women see the same thing.
However, men and women possibly attend to markedly different
features of the pictures. Sex differences in attention to visual
sexual stimuli would have implications for future interpretations
hypothesis that previously reported sex differences in response
to visual sexual stimuli may reflect sex differences in viewing
patterns to sexual stimuli.
Our theoretical orientation supposes that cognitive processes,
specifically attention, mediate the specific genital and subjective
responses to visual sexual stimuli in men and women. Where a
person looks is the first event regulating the response to stimuli
since those aspects of a stimulus attended to are preferentially
processed and encoded (Yantis, 2005). It is possible that men and
women differ in how they attend to the same stimuli because
multiple cognitive factors determine individual attentionMen and women exhibit different neural, genital, and subjective arousal responses to visual sexual stimuli. The source of these sex differences
is unknown. We hypothesized that men and women look differently at sexual stimuli, resulting in different responses. We used eye tracking to
measure looking by 15 male and 30 female (15 normal cycling (NC) and 15 oral contracepting (OC)) heterosexual adults viewing sexually explicit
photos. NC Women were tested during their menstrual, periovulatory, and luteal phases while Men and OC Women were tested at equivalent
intervals, producing three test sessions per individual. Men, NC, and OC Women differed in the relative amounts of first looks towards, percent
time looking at, and probability of looking at, defined regions of the pictures. Men spent more time, and had a higher probability of, looking at
female faces. NC Women had more first looks towards, spent more time, and had a higher probability of, looking at genitals. OC Women spent
more time, and had a higher probability of, looking at contextual regions of pictures, those featuring clothing or background. Groups did not differ
in looking at the female body. Menstrual cycle phase did not affect women's looking patterns. However, differences between OC and NC groups
suggest hormonal influences on attention to sexual stimuli that were unexplained by subject characteristic differences. Our finding that men and
women attend to different aspects of the same visual sexual stimuli could reflect pre-existing cognitive biases that possibly contribute to sex
differences in neural, subjective, and physiological arousal.
' 2007 Elsevier Inc. All rights reserved.
Keywords: Sexual stimuli; Sex differences; Eye tracking; Oral contraceptivesAbstractSex differences in viewing se
study in men
Heather A. Rupp
a
Department of Psychology and Center for Behavioral
b
The Kinsey Institute for Research in Sex, Gender and Reproduction
Received 14 October 2006; revised 27
Available online

Corresponding author. The Kinsey Institute for Research in Sex, Gender and
Reproduction, Indiana University, Morrison Hall 313, Bloomington, IN 47405,
USA. Fax: +1 812 855 8277.
E-mail address: hrupp@indiana.edu (H.A. Rupp).
0018-506X/$ - see front matter ' 2007 Elsevier Inc. All rights reserved.
doi:10.1016/j.yhbeh.2007.01.008ual stimuli: An eye-tracking
and women
,


, Kim Wallen
a
roscience, Emory University, Atlanta, GA 30322, USA
diana University, Morrison Hall 313, Bloomington, IN 47405, USA
uary 2007; accepted 30 January 2007
February 2007
2007) 524–533
www.elsevier.com/locate/yhbehspecific motivation and the individual's assessment of what
aspects of an image are interesting, important, and warrant
attention (Balcetis and Dunning, 2006; Henderson, 2003;

s anIsaacowitz, 2006). Motivational state biases information pro-
cessing focusing attention to specific aspects of stimuli (Balcetis
and Dunning, 2006; Mogg et al., 2003; Isaacowitz, 2006). Men
and women may pay attention to different aspects of sexual
stimuli due to sex differences in what they find most attractive
and arousing in a sexual context and differences in levels of
sexual motivation (Balcetis and Dunning, 2006). Levels of
general sexual arousal are higher with focused attention
(Koukounas and McCabe, 1997; Geer and Fuhr, 1976). Thus,
different viewing strategies may produce different patterns of
maximal arousal in men and women to the same stimulus.
It is unknown what characteristics are important for men and
women in their evaluation of visual sexual stimuli, and
therefore, it is unknown what factors men and women attend
to in order to maximize arousal. A recent eye-tracking study
suggests that the bodies of opposite sex nudes capture the
majority of the viewer's attention (Lykins et al., 2006). This
study found that men and women increased looking at the
bodies and decreased looking at the faces and context in erotic
compared to nonerotic stimuli. However, men and women in
this previous eye-tracking study did not view the same stimuli
making comparisons between the sexes impossible. Further-
more, the Lykins et al. (2006) study used opposite-sex nudes as
the stimuli, rather than couples engaged in sexual activity,
which are typically used in the assessment of sex differences in
response to visual sexual stimuli (e.g., Hamann et al., 2004;
Janssen et al., 2003; Laan et al., 1994). Studies using visual
sexual stimuli depicting heterosexual intercourse found that
men and women differ in their content preferences. Specifically,
men and women rated visual sexual stimuli chosen by a member
of their own sex as more sexually arousing than stimuli chosen
by a member of the opposite sex (Laan et al., 1994; Janssen et
al., 2003). Unfortunately, the characteristics that differentiated
male from female selected stimuli were undefined. Possibly,
there could be sex differences in men and women's interest in
the contextual vs. specifically sexual elements of visual sexual
stimuli; with women looking more at contextual and nonsexual
details than do men. Support for this notion comes from the
work finding that with repeated exposure to visual sexual
stimuli, women changed their viewing strategy in later sessions
and looked at contextual features of the stimuli to maintain
arousal, whereas men did not (Laan and Everaerd, 1995). Thus,
previous evidence for sex differences in attention to or interest
in particular characteristics of visual sexual stimuli is
inconclusive.
In addition to differences between sexes in attention to visual
sexual stimuli, it is also possible that there are differences
among women based on their use of hormonal contraceptives.
Effects of hormonal contraceptives on sexual motivation may
influence women's gaze patterns to sexual stimuli by altering
visual perception (Balcetis and Dunning, 2006; Isaacowitz,
2006). In women not using oral contraceptives, sexual desire,
masturbation, and instances of sexual initiation fluctuate over
the cycle, with highest levels during the periovulatory period,
H.A. Rupp, K. Wallen / Hormonewhen sex steroid levels are also highest (reviewed in Wallen,
2001). Because women using oral contraceptives do not
experience the same magnitude of hormonal fluctuations(Carlstrom et al., 1978), one would expect them to have lower
and less variable sexual motivation than cycling women. Lower
sexual motivation in oral contracepting women generally
appears to be the case, although there are conflicting findings
(reviewed in Davis and Castano, 2004).
We investigated the hypothesized sex and within female
group differences in viewing patterns of visual sexual stimuli by
monitoring eye movement while subjects viewed sexual stimuli.
A previous study using eye-tracking methodology to investigate
gaze patterns of men and women on pictures of male and female
typical toys (Alexander, 2006) found not only sex differences in
gaze patterns, but also a possible relationship between prenatal
androgen exposure and visual preferences, supporting the use of
this technology in the investigation of sex and contraceptive use
differences in attention to visual sexual stimuli. It should be
noted that because previous research is so limited addressing
what components of sexual stimuli are salient for men and
women, it was not possible to make strong directional
predictions based on the limited literature available. However,
we expected sex differences in attention to the stimuli.
Specifically, we predicted that viewing patterns would differ
between men and women such that men would look more at
explicitly sexual components, such as the genitals and female
body, whereas women would be more likely than men to be
interested in faces and the context of the photos, such as the
background and clothing. Due to differences in hormonal
profiles, we hypothesized that women's looking patterns would
differ with the type of contraceptive use. Predictions based on
hormonal state were especially exploratory because, again, we
do not know what elements of a visual sexual stimulus are
associated with higher or lower sexual motivation. However, we
expected cycling women (NC Women) to show more interest in
the explicitly sexually aspects of the stimuli, which we thought
would be the genitals and male body, than women using oral
contraceptives (OC Women). Conversely, we expected that OC
Women would look more at the contextual elements of the
stimuli, specifically the clothing and background regions, than
NCWomen. Considering the previously reported fluctuations in
sexual motivation across the menstrual cycle (Wallen, 2001),
we also predicted that the menstrual phase at the time of testing
may influence gaze patterns such that women would look at
more sexually salient aspects of the stimuli when estradiol was
highest, around ovulation for NC Women and around
menstruation for OC Women (Van Heusden and Fauser,
1999). We report here that men and women presented with
the same sexual stimuli did not view them in the same manner
and also women's viewing patterns differed according to oral
contraceptive use.
Methods
Subjects
Subjects were recruited from Atlanta area graduate and professional schools
by email and flyers. Participants first completed an application that included a
525d Behavior 51 (2007) 524–533consent form and a questionnaire that asked them their data of birth, whether
they used oral contraceptives, whether they had been sexually active in the last
month, some questions from the Brief Index of Sexual Function (BISF, Taylor et