Sex Differences in Young Adults’ Attraction to Opposite-Sex Friends: Natural Sampling versus Mental Concepts

Abstract

When young adults are asked to either think of an opposite-sex friend or bring an opposite-sex friend to the lab, men report much more attraction to their friend than women do (Bleske-Rechek et al., 2012; Kaplan and Keys, 1997). In two studies, we utilized a naturalistic sampling strategy to obtain our friendship dyads. We approached and surveyed male-female dyads who were lounging at a university student center and found that the mean difference between male and female friends’ attraction to one another was weak and statistically unreliable. We speculated that the opposite-sex friends that men and women find themselves with in their everyday life might be different from the opposite-sex friends who come to mind when asked by researchers to think of their friends. Men’s and women’s mating adaptations, which differ particularly in attention to attractiveness and proclivity toward short-term sex, might be reflected in how men and women conceptualize opposite-sex friends; hence, previous studies may have documented a stronger sex difference in attraction because men and women in those samples had different types of people in mind when they thought about opposite-sex friends. To test that possibility, we asked young adults to “think of an opposite-sex friend” and then choose descriptors for that person. Men less often than women characterized the person as “a friend” and more often than women characterized the person as someone they were “attracted to.” We conclude that men’s and women’s everyday experiences with opposite-sex friends differ from their mental conceptions of opposite-sex friends.

Full text

RESEARCH ARTICLE
Sex Differences in Young Adults’Attraction to Opposite-Sex
Friends: Natural Sampling versus Mental Concepts
April Bleske-Rechek
1
&Whitney E. Joseph
1
&Heather Williquette
1
&Bryan Donovan
1
Published online: 11 May 2016
#Springer International Publishing 2016
Abstract When young adults are asked to either think of an
opposite-sex friend or bring an opposite-sex friend to the lab,
men report much more attraction to their friend than women
do (Bleske-Rechek et al. Journal of Social and Personal
Relationships, 29: 569–596, 2012; Kaplan and Keys Journal
of Social and Personal Relationships, 14: 191–206, 1997). In
two studies, we utilized a naturalistic sampling strategy to
obtain our friendship dyads. We approached and surveyed
male-female dyads who were lounging at a university student
center and found that the mean difference between male and
female friends’attraction to one another was weak and statis-
tically unreliable. We speculated that the opposite-sex friends
that men and women find themselves with in their everyday
life might be different from the opposite-sex friends who come
to mind when asked by researchers to think of their friends.
Men’s and women’s mating adaptations, which differ particu-
larly in attention to attractiveness and proclivity toward short-
term sex, might be reflected in how men and women concep-
tualize opposite-sex friends; hence, previous studies may have
documented a stronger sex difference in attraction because
men and women in those samples had different types of peo-
ple in mind when they thought about opposite-sex friends. To
test that possibility, we asked young adults to “think of an
opposite-sex friend”and then choose descriptors for that per-
son. Men less often than women characterized the person as “a
friend”and more often than women characterized the person
as someone they were “attracted to.”We conclude that men’s
and women’s everyday experiences with opposite-sex friends
differ from their mental conceptions of opposite-sex friends.
Keywords Opposite-sex friends .Friendship .Attraction .
Naturalistic sampling
Among young adults in modern society, friendships with
members of the opposite sex are common (Monsour 2002)
and highly valued (Baumgarte and Nelson 2009). One of the
unique challenges for opposite-sex friends is convincing
others that the relationship is platonic (O’Meara 1989;
Schoonover and McEwan 2014; Werking 1997). Perhaps that
challenge is rooted in a kernel of truth, because approximately
half of romantically involved couples report that they were
friends prior to becoming romantically involved (Hunt et al.
2015), and young men and women in various contexts report
experiencing some form of attraction to, or sexual involve-
ment with, their opposite-sex friends (Afifi and Faulkner
2000; Kaplan and Keys 1997;Reeder2000;Swain1992).
Evolutionary researchers have proposed that opposite-sex
friendships might trigger men’s and women’smating strate-
gies (Bleske and Buss 2000; Bleske-Rechek et al. 2012). For
example, men’s stronger attention to physical attractiveness
(Buss 1989) and short-term mating orientation (Buss and
Schmitt 1993), relative to women’s, should manifest in their
experiences with opposite-sex friendships. Indeed, one of the
most consistent findings on attraction in young adults’
opposite-sex friendships is that men report more attraction to
their opposite-sex friends than women do (Bleske-Rechek and
Buss 2001; Kaplan and Keys 1997; Bleske-Rechek et al.
2012). For example, Kaplan and Keys (1997) had US under-
graduates tell them about a close cross-sex friend of theirs;
when the participants reported how physically attractive they
thought their closest cross-sex friend was, how much they
*April Bleske-Rechek
bleskeal@uwec.edu
1
Psychology Department, University of Wisconsin-Eau Claire, 105
Garfield Avenue, Eau Claire, WI 54702, USA
Evolutionary Psychological Science (2016) 2:214–219
DOI 10.1007/s40806-016-0056-6

would enjoy having sex with their friend, and how often they
touched their friend, men’s ratings were substantially higher
than women’s (mean difference of 3.5 on a 21-point scale;
d= 0.72). When Bleske-Rechek and Buss (2001) asked a sam-
ple of US undergraduates to think about their “closest, most
important opposite-sex friend who is not a long-term romantic
partner,”men rated their friend as more sexually attractive
than women did (mean difference of 1.5 on a seven-point
scale; d= 0.45) and reported more frequent desire to have
sex with their friend than women did (mean difference of
1.5 on a seven-point scale; d= 0.41). In another study,
Bleske-Rechek et al. (2012) asked young men and women
to bring with them to the lab a “friend of the opposite sex
who was neither from class nor a family member or romantic
partner.”The researchers assessed sexual attraction and phys-
ical attraction (alpha= .93) and found that in these dyads, men
reported more attraction to their friend than women did (mean
difference of 1.0 on a nine-point scale; d= 0.66). In the aggre-
gate, these findings suggest a moderate-sized sex difference in
attraction to opposite-sex friends, even those presumably se-
lected according to platonic specifications.
In study 1, we were interested in replicating the difference
between young men’s and young women’s attraction to their
opposite-sex friends. We approached opposite-sex dyads who
were passing time at a university student union and, upon their
consent, surveyed each partner independently about their per-
ceptions of one another and their relationship.
Study 1
Method
During the 2013–2014 academic year, a male-female pair of
researchers approached young adult male-female dyads who
were eating or sitting together at a university student union
during the lunch hour. The researchers invited them to partic-
ipate in a brief “study of dyads.”Refusal to participate was
uncommon (in fact, several students approached the re-
searchers asking what they were doing and proceeded to par-
ticipate); however, a few dyads declined because they were
heading to class or getting ready to get in line for food. Upon
consent, partners were physically separated by the researchers
and stood with a clipboard as they completed the question-
naire. In addition to ratings of their own and their partner’s
attractiveness and personality that were included for purposes
outside of the current analysis, participants used a seven-point
scale to report the degree to which they were physically
attracted to their partner (notatallto moderately to
extremely).
At the end of the one-page questionnaire, participants in-
dependently reported their dyad relationship status as “We are
just friends,”“We are in a romantic relationship,”or “Other.”
We did not include an additional question pertaining to each
individual’s relationship status (as single or involved). We
omitted two dyads that included one participant of homosex-
ual orientation, two who were cousins, two who provided
discrepant reports of their relationship status (i.e., friends ver-
sus romantic partners), and two that included one member
who said it was too early to tell what their relationship status
was. The final sample included 40 pairs of opposite-sex
friends, with a mean friendship duration of 99.24
± 25.61 weeks. Mean ages were 19.70 ± 1.47 for men and
19.37 ± 1.28 for women. The dataset also included ratings
from 37 dating couples, but we focus here on just the re-
sponses from friendship dyads.
Results and Discussion
Men’s and women’s mean level of physical attraction to the
opposite-sex friend they were with when we surveyed them
was low to moderate. As displayed in Fig. 1, a within-sample t
test revealed that men (M= 3.93, SD = 1.53) and women
(M= 3.35, SD = 1.76) did not differ statistically [t(39) = 1.64,
p= .109] in their reported levels of attraction (M
d
=0.58 [95%
CI −0.13, 1.28]), and the magnitude of the sex difference was
weak, d=0.26. Both men and women varied widely in their
reported attraction: 8 % of men and 23 % of women reported
they were “not at all”attracted to their friend, and 60 % of men
and 50 % of women reported at least moderate attraction.
In short, we failed to replicate the significant sex difference
documented in previous studies (Bleske-Rechek and Buss
2001; Bleske-Rechek et al. 2012; Kaplan and Keys 1997).
The sex difference we observed was small in magnitude, rath-
er than moderateto strong, and not statistically significant. We
speculated that our sampling method was an explanatory fac-
tor. That is, we had not asked people to tell us about a friend of
theirs but instead approached friends in their “natural habitat.”
Are the members of the opposite sex with whom young adults
pass their time in an everyday context different from the mem-
bers of the opposite sex that they visualize when researchers
ask about their friends? Before pursuing that possibility fur-
ther, we first attempted to replicate the pattern we had just
observed.
Study 2
Method
Study 2 took place during the subsequent academic year; it
was embeddedin a broader study of similarity between friends
and romantic partners in moral attitudes and values. As in
study 1, dyads were approached and, upon consent, the part-
ners independently completed a brief questionnaire. Toward
the end of the questionnaire, participants used a seven-point
Evolutionary Psychological Science (2016) 2:214–219 215

scale to report the degree to which they were physically
attracted to their partner (notatallto moderately to
extremely). Then, participants selected the dyad’srelationship
status from several options: acquaintance, casual friend, close
friend, romantic partner, roommate, sibling/relative, and other.
There were three pairs who differed in their perception of their
friendship as close versus casual, but there were no pairs with
discrepant views on their relationship status as friends versus
romantically involved. As in study 1, the questionnaire did not
include an additional item pertaining to each individual’sre-
lationship status (as single or involved). Refusal was uncom-
mon, with a total of 139 dyads involved. For purposes of the
current research question, however, we report only on the
opposite-sex friends who participated. The sample included
38 pairs of opposite-sex friends (mean friendship duration of
50.87 ± 9.32 weeks), with men’s mean age at 20.50
±1.80 years and women’s mean age at 19.84± 1.35 years.
Results and Discussion
Study 2 replicated the pattern from study 1. As displayed in
Fig. 1, young men (M= 3.76, SD = 1.95) and women
(M= 3.11, SD = 1.69) did not differ statistically [t(37) = 1.83,
p= .076] in their mean level of physical attraction to one an-
other (M
d
=0.66[95% CI−0.07, 1.39]), and the magnitude of
the sex difference was weak, d=0.30. Both men and women
varied widely in their reported attraction: 21 % of men and
23 % of women reported they were “not at all”attracted to
their friend, and 62 % of men and 45 % of women reported at
least moderate attraction.
In studies 1 and 2, the sex difference in attraction to
opposite-sex friends was not statistically significant and was
weaker than what has been documented in previous research.
One possibility is that each individual study was underpow-
ered due to the sample size. Indeed, when we compiled the
two samples, the mean difference was statistically significant,
t(77) = 2.47, p= .016 (M
d
= 0.62 [95 % CI 0.12, 1.11]).
However, even compiled across the two samples, our analysis
revealed a weaker sex difference (d=0.28) than what has been
documented in previous studies using dyads. For example,
Bleske-Rechek et al. (2012, study 1) used a similar-sized sam-
ple of dyads (N=88) and found a mean sex difference of 1.0
(on a seven-point scale), with an effect size of 0.66, despite
that participants were given instructions that should have led
them to select a platonic friend. (In that study, participants
were asked to bring in “a friend of the opposite sex who was
neither from class nor a family member or romantic partner.”)
In two other studies, Koenig et al. (2007) asked college stu-
dents to recruit an opposite-sex friend to participate with them
in a study of relationships (Ns=119pairsand99pairs).
Although Koenig et al. did not report inferential statistics re-
lated to sex differences in attraction, Figs. 1 and 3 of their
paper illustrate that the mean sex difference in sexual attrac-
tion for both of their samples was greater than 1.0 on their
seven-point scale. We tentatively conclude, then, that differ-
ences in sample size do not fully explain why the mean dif-
ference that we obtained in our samples was weaker than that
obtained in other studies.
Another explanation for the weaker sex difference we ob-
tained has to do with our sampling method. In studies 1 and 2,
we sampled naturally occurring pairs of friends, which ap-
pears to not have been done before in research on opposite-
sex friends. That is, rather than ask men and women to select a
friend to report on or bring to the lab, we went to a high-traffic
lounging area where we were likely to find friends spending
time together. The “friends”that men and women find them-
selves with at any given time may not be the same friends who
come to mind when they are asked to think of an opposite-sex
friend. Indeed, men and women may differ in their mental
conceptions of opposite-sex friendship because differences
Fig. 1 Men’s and women’s mean
level of physical attraction to the
opposite-sex friend they were
with when they were approached
216 Evolutionary Psychological Science (2016) 2:214–219

in men’s and women’s mating adaptations might influence
how they think about friends. For example, men’sstronger
orientation toward short-term mating relative to women’s
(Buss and Schmitt 1993;Schmitt2005) corresponds with dif-
ferences in how the sexes select and feel about their opposite-
sex friends. Men more than women view sexual attraction as a
benefit of opposite-sex friendships (Bleske and Buss 2000),
and men more than women desire (Bleske-Rechek and Buss
2001) and prioritize (Lewis et al. 2011,2012)attractivenessin
an opposite-sex friend. Men also are more likely than women
to report having initiated friendships with a member of the
opposite sex because of their feelings of attraction toward
them (Salkicevic 2014). It is perhaps not surprising, then, that
in studies in which young adults have been asked to either
think of an opposite-sex friend or bring an opposite-sex friend
to the lab, men report more attraction (Bleske-Rechek et al.
2012) and more sexual and romantic desire toward that person
than women do (Bleske-Rechek and Buss 2001;Kaplanand
Keys 1997). Thus, in study 3, we tested the hypothesis that
men and women have somewhat different types of people in
mind when they think of opposite-sex friends.
Study 3
Method
Participants
Through social networksites and course research participation
subject pools, we invited young adults at a large Midwestern
university to participate in an online study of “Friendship
Definitions.”We omitted five men who reported a homosex-
ual orientation and 15 women and nine men who did not
completely follow the survey instructions (as described be-
low). The final sample included 114 men and 192 women
(M
age
= 19.32, SD = 2.11). Of those, 38 % were currently in-
volved in a romantic relationship.
Instruments and Procedure
Previous researchers have used varying degrees of specificity
in the instructions they give to men and women when asking
about opposite-sex friends. Thus, we prepared two sets of
instructions. One (“general”) set of instructions read, “Please
think of an opposite-sex friend”; the other (“specific”) set
read, “Please think of an opposite-sex friend who is not a
family member or current romantic partner.”Each participant
was randomly assigned to one of the two sets of instructions
and was then asked to type the first name of the friend they
thought of so that we could be certain they had a specific
person in mind (as noted above, 24 participants who did not
follow this instruction were omitted from the dataset). Then,
participants were brought to the next screen. It contained one
question: “Which of the following describes the person who
has come to mind?”Participants could check one or both: “A
person of the opposite sex who is a friend”and “Apersonof
the opposite sex who I am physically attracted to.”On the
final screen, participants reported their sex, current romantic
relationship status, age, and sexual orientation.
Results and Discussion
The results are displayed in Fig. 2. Regardless of instructions
given, men’s characterizations of the person they had thought
of differed from women’s (general instructions χ
2
(2,
n= 155) = 10.71, p=.005, V= .26; specific instructions χ
2
(2,
n= 150) = 12.21, p=.002, V=.29).Menwerelesslikelythan
women to characterize the person as a friend and more likely
than women to characterize the person either as someone they
were attracted to or as both a friend and someone they were
attracted to. Even among the subset of participants who were
currently involved in a romantic relationship and told to think
of a friend who was not a family member or current romantic
partner, fewer men (79 %) than women (97 %) characterized
the person as a friend, and more men (21 %) than women
(3 %) characterized the person as both a friend and someone
they were attracted to, χ
2
(1, n=61)=5.40, p=.020, V=.30
(no members of this subset characterized the person only as
someone they were attracted to).
General Discussion and Conclusion
In past studies of opposite-sex friendship, men have reported
more physical attraction, sexual attraction, and romantic inter-
est toward their friends than women have (Afifi and Faulkner
2000; Bleske-Rechek and Buss 2001; Bleske-Rechek et al.
2012;KaplanandKeys1997). However, when we
approached and surveyed male-female friends who were en-
gaged in everyday interactions, both sexes varied widely in
their level of attraction toward the friend they were with when
approached, and the mean difference was weaker than what
has been documented before. We reasoned that in past studies,
the sex difference in attraction occurred because men and
women had fundamentally different types of people in mind
when they thought of an “opposite-sex friend.”In study 3, we
tested that hypothesis by asking men and women about the
person who came to mind when we asked them to think of an
opposite-sex friend. We found that men were less likely than
women to characterize the person only as a friend, and men
were more likely than women to characterize the person as
either someone they are attracted to or as both a friend and
someone they are attracted to. This pattern implies that men
more often mentally define an opposite-sex friend as “amem-
ber of the opposite sex to whom I am attracted and would
Evolutionary Psychological Science (2016) 2:214–219 217

pursue given the opportunity”and women more often mental-
ly define an opposite-sex friend as “a friend of the opposite
sex.”
Future work needs to address important limitations of the
current set of studies. First, in studies 1 and 2, we asked men
and women only how physically attracted they were to their
friend. We did not ask them how sexually and romantically
attracted they were to the friend, and the findings may have
been different had we asked those questions. That said, ratings
of physical and sexual attraction have been essentially redun-
dant in other studies (Bleske-Rechek et al. 2012), and in
Koenig et al. (2007, Figs. 1 and 3), the sex difference in ro-
mantic attraction was noticeably smaller than was the sex
difference in sexual attraction. Regardless, in future research,
we aim to obtain participants’ratings of sexual and romantic
attraction as well as physical attraction. Second, the pattern of
results from study 3 is consistent with the hypothesis that men
and women differ in how they conceptualize opposite-sex
friends, but it is also consistent with the possibility that men
more strongly value friends who are physically attractive and
therefore are more likely than women to think of their more
physically attractive friends first (and hence be more attracted
to them). We are currently planning a study that might help us
address these issues. We plan to use natural sampling to obtain
a set of male-female friends. After surveying the dyad mem-
bers and taking their pictures, we will ask each of them to
nominate another opposite-sex friend of theirs to participate
in a second phase of the research with them. Each original
participant will then come to the lab with their nominated
friend (who would also be photographed), and we will survey
both members of that dyad as well. With this design, we will
be able to compare each participant’s attraction toward a
friend obtained via natural sampling with their attraction to-
ward a friend obtained via mental conceptions. With subse-
quent ratings from naïve judges of all participants’attractive-
ness, we will also be able to compare the physical attractive-
ness of each participant’s friend obtained via natural sampling
and each participant’s friend obtained via mental conceptions.
Another important limitation is that our samples were rel-
atively homogenous in both age and ethnicity. The vast ma-
jority of research on opposite-sex friendship, in general, has
utilized college student samples from western societies.
Future research with participants of varied ages and ethnic
backgrounds will provide useful information on the psycho-
logical mechanisms underlying people’s mental representa-
tions of opposite-sex relationships. It also would be helpful
to obtain samples of male-female friendship pairs from the
large variety of natural contexts (besides school) in which
friends meet and spend time together, such as the workplace,
music and sporting events, and community organizations. In
future studies, we aim to sample more broadly to determine
how the environment from which we sample is related to
men’s and women’s friendship dynamics. With these caveats
in mind, we tentatively conclude that young adult men’sand
women’s everyday experiences with opposite-sex friends dif-
fer systematically from their mental representations of
Fig. 2 Men’sandwomen’s
description of the person who
came to mind when asked to think
of an opposite-sex friend (left
columns) or when asked to think
of an opposite-sex friend who is
not a family member or current
romantic partner (right columns)
218 Evolutionary Psychological Science (2016) 2:214–219

opposite-sex friends. As has been illustrated in other contexts,
such as in the study of physical attractiveness (Kniffin and
Wilson 2004) and long-term romantic partnerships (Driver
and Gottman 2004), a deeper understanding of opposite-sex
friendship dynamics might be garnered from studying them
under naturalistic conditions.
Acknowledgments This research was funded by the Office of
Research and Sponsored Programs at the University of Wisconsin-Eau
Claire.
Compliance with Ethical Standards
Conflict of Interest The authors declare that they have no conflict of
interest.
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