ae
Psychoneuroendocrinology (2011) 36, 1257—1260
a va i l a ble at ww w. sc ie nce di r ect . com
j our na l h omepa g e: www.e l se Department of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK
Received 22 October 2010; received in revised form 8 February 2011; accepted 8 February 2011
1. Introduction
Considerable recent research effort suggests that attractive-
ness judgements of male faces represent a trade-off between
signals of heritable quality (‘good genes’) and cues to pro-
social personality. Much of this work has considered sexually
dimorphic features (facial masculinity or femininity) to pro-
vide useful information about their bearer. For example,
masculinity in male faces is proposed to be an honest signal
of high male quality (Folstad and Karter, 1992). On the other
hand, masculine faces are seen as possessing fewer desirable
personality traits than feminized ones: they are perceived to
be less warm, cooperative, and honest (Penton-Voak and
Perrett, 2001).
Some research investigating facial attractiveness and
preferences for male traits has provided supporting evidence
for a preference for relatively feminized male faces, whereas
other studies have suggested that masculinized faces are
preferred instead. In contrast, in women, facial femininity is
clearly linked to attractiveness and is associated with per-
ceived warmth, cooperativeness and honesty (see Rhodes,
2006, for a review).
In the present study, we investigate how the neuropeptide
oxytocin (OT) might affect preferences for masculinity and
KEYWORDS
Oxytocin;
Masculinity preferences;
Attractiveness;
Social perception
Summary Preferences for sexually dimorphic traits in men’s faces are consistent with a trade-
off between cues to indirect (genetic) and direct (prosociality) benefits, associated perceptually
with relative masculinity and femininity respectively. As the neuropeptide oxytocin (OT) has been
shown to promote social perception, we hypothesized that temporary OT elevation would result
in a preference for masculinity in men’s faces, by reducing the apparent social costs of masculine
traits. In a double-blind, placebo-controlled study, 96 participants received either 24 IU OT or
placebo. They then completed a computer task in which they used the mouse to alter the shape of
displayed men’s and women’s faces, making them look more or less masculine. Participants were
instructed to make each face as attractive as possible. OT administration led to a trend for a
relative preference for masculinity in men’s faces but did not affect preferences for femininity in
women’s faces, and this effect occurred irrespective of the participant’s sex. We tentatively
speculate that OT may ‘mask’ negative personality attributions normally associated with
masculine male faces. These results may be pointing to the role of personality attribution in
attractiveness judgements, and the role of OT in social perception.
# 2011 Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: +44 117 928 8545;
fax: +44 117 928 8588.
E-mail address: at4194@bris.ac.uk (A. Theodoridou).
0306-4530/$ — see front matter # 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.psyneuen.2011.02.004SHORT COMMUNICATION
Oxytocin administration le
masculinized male faces
Angeliki Theodoridou *, Angela C. Rowds to a preference for
, Peter J. Rogers, Ian S. Penton-Voak
v ie r.c om/l oca te/ psyne ue n

1258 A. Theodoridou et al.femininity in human faces. Studies on the effects of OT on
social cognition demonstrate that it improves mind-reading
ability (Domes et al., 2007), promotes socially reinforced
learning and emotional empathy (Hurlemann et al., 2010),
attenuates negative evaluations of fear-associated faces and
attenuates amygdala activity (Petrovic et al., 2008),
increases gaze to the eye region (Guastella et al., 2008),
and increases perceived facial attractiveness and trust-
worthiness (Theodoridou et al., 2009). Here, we present
masculinized and feminized male and female faces to male
and female participants in a task employed by Penton-Voak
et al. (2003), and examine the effect of intranasal OT
administration on preferences for these faces. Given that
OT appears to promote positive social perception, we
hypothesize that it should attenuate the attribution of nega-
tive personality traits to masculinized male faces (such as low
warmth, cooperativeness and honesty) and in turn lead to a
preference for these faces. Artificially raising the perceived
positive qualities of faces should remove the apparent costs
of facial masculinity: masculine faces may then signal bio-
logical quality, without the concomitant cost of antisociality.
In contrast, preferences for feminine female faces are
expected to be comparable for the two treatment groups
as feminine faces are already associated with both biological
quality and prosociality.
Finally, the present study examines whether exogenous
OT administration affects preferences for facial masculinity
and femininity differently in men and women. In the absence
of direct evidence for sexual dimorphism in the behavioural
effects of OT in humans (see Ditzen et al., 2009; Guastella
et al., 2009; Shamay-Tsoory et al., 2009; but also see Domes
et al., 2010), we hypothesize that exogenous OT will affect
preferences for facial masculinity and femininity similarly in
men and women.
2. Methods
2.1. Participants
Ninety six participants (50% female) were recruited mainly
from the student population of the University of Bristol, UK
(female mean age = 21.4 years, male mean age = 21.5 -
years). Forty (23 females and 17 males) were romantically
attached. Participation was rewarded with either £15 or
course credit. Baseline questionnaires confirmed that no
participant suffered from severe depression or trait anxiety
assessed using the MDI (Bech, 1997), and STAI (Spielberger
et al., 1983) respectively. The study protocol was reviewed
and approved by the University of Bristol Faculty of Science
Human Research Ethics Committee.
2.2. Design
In this double-blind placebo controlled study, participants
were randomly assigned to receive an intranasal dose of either
24 IU OT (Syntocinon Spray, Novartis; 3 puffs per nostril, each
puff containing 4 IU OT) or placebo. The placebo sprays con-
tained all ingredients present in the OT sprays except for OT.
We investigated the effect of OTon positive evaluations of
others by measuring preferences for masculinity and femi-
ninity in male and female faces, respectively. Additionally,we assessed the effect of OT on mood, wakefulness and
calmness using the Multidimensional Mood State Question-
naire (Steyer et al., 1997). These measures were taken as
part of a larger study in the same participants as in Theodor-
idou et al. (2009) in a session lasting approximately 60 min.
2.3. Stimuli
Six male and six female face sequence trials were presented
on a computer screen. The male sequences had been con-
structed from six groups of male and female faces (a Japa-
nese group and four groups of Caucasian faces and an African-
Caribbean group; see Penton-Voak et al., 2003 for details of
these test stimuli). Using the shape differences between
male and female composites from each group, masculinized
and feminized versions of each composite were created. Nine
equally spaced intermediate morphed stimuli were gener-
ated between the masculinized and feminized version of
each face, creating 11 image sequences in which a given
face smoothly changed from a more masculine to a more
feminine appearance.
During each trial, left or right mouse movement altered
the shape of the displayed face by making it more or less
masculine; the relationship between direction of mouse
movement and masculinity/femininity of the displayed face
was counterbalanced on a trial by trial basis. Images were
presented in a randomized order within same stimuli sex
blocks. Participants were instructed to make the face look as
attractive as possible by moving the mouse. Six female and
six male face-sequence trials were presented. Mean scores
above zero indicate a preference for more masculine male
faces and more feminine female faces, accordingly, while
scores below zero correspond to a preference for less mascu-
line male faces and less feminine female faces. A score of
zero indicates a preference for the average male and the
average female face accordingly.
2.4. Procedure
Participants were tested individually and were instructed to
abstain from alcohol, caffeine and nicotine for 24 h prior to
testing and all food and drink, except water, for 2 h before
testing. At the start of the experimental session, informed
signed consent was obtained and participants self-adminis-
tered a single intranasal dose of either OT (n = 51, 25 males)
or placebo (n = 45, 23 males). Beginning 25 min after drug
administration a battery of tasks were undertaken in two
blocks in a counterbalanced order. Block 1 tasks included the
face preference task. Block 2 included the rating of mood,
wakefulness and calmness. Forty seven participants started
the face preference task approximately 35 min after drug
administration and 49 participants started it approximately
55 min after drug administration.
2.5. Data analysis
The data on masculinity and femininity preferences were
analyzed using analysis of variance (ANOVA) with drug (OT or
placebo), sex of participant (male or female), and block (i.e.,
time of face task after drug administration) as between-
subjects factors, and sex of face (male or female) as a