Study 2 took place during the subsequent academic year; it was embedded in 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 partners independently completed a brief questionnaire. Toward the end of the questionnaire, participants used a seven-point scale to report the degree to which they were physically attracted to their partner (not at all to moderately to extremely). Then, participants selected the dyad’s relationship 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’s relationship status (as single or involved). Refusal was uncommon, 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 another (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 underpowered 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 sample 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 students to recruit an opposite-sex friend to participate with them in a study of relationships (Ns = 119 pairs and 99 pairs). Although Koenig et al. did not report inferential statistics related to sex differences in attraction, Figs. 1 and 3 of their paper illustrate that the mean sex difference in sexual attraction for both of their samples was greater than 1.0 on their seven-point scale. We tentatively conclude, then, that differences in sample size do not fully explain why the mean difference that we obtained in our samples was weaker than that obtained in other studies.
Another explanation for the weaker sex difference we obtained has to do with our sampling method. In studies 1 and 2, we sampled naturally occurring pairs of friends, which appears 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 themselves 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 in men’s and women’s mating adaptations might influence how they think about friends. For example, men’s stronger orientation toward short-term mating relative to women’s (Buss and Schmitt 1993; Schmitt 2005) corresponds with differences 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) attractiveness in 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; Kaplan and 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.