Research Article: Olfactory Performance Is Predicted by Individual Sex-Atypicality, but Not Sexual Orientation

Date Published: November 7, 2013

Publisher: Public Library of Science

Author(s): Lenka Nováková, Jaroslava Varella Valentová, Jan Havlíček, Fernando de Castro.

http://doi.org/10.1371/journal.pone.0080234

Abstract

Many previous studies have reported robust sex differences in olfactory perception. However, both men and women can be expected to vary in the degree to which they exhibit olfactory performance considered typical of their own or the opposite sex. Sex-atypicality is often described in terms of childhood gender nonconformity, which, however, is not a perfect correlate of non-heterosexual orientation. Here we explored intrasexual variability in psychophysical olfactory performance in a sample of 156 individuals (83 non-heterosexual) and found the lowest odor identification scores in heterosexual men. However, when childhood gender nonconformity was entered in the model along with sexual orientation, better odor identification scores were exhibited by gender-nonconforming men, and greater olfactory sensitivity by gender-conforming women, irrespective of their sexual orientation. Thus, sex-atypicality, but not sexual orientation predicts olfactory performance, and we propose that this might not be limited to olfaction, but represent a more general phenomenon.

Partial Text

Numerous recent studies have reported sex differences in personality characteristics, cognition, and behavior [1-3]. For instance, robust sex differences have been repeatedly found in physical aggression, which is on average higher in males [4], and in empathy, in which females typically score higher than males [5]. Furthermore, some of these sex differences seem to appear at least as early as during infancy and preschool age, as suggested, for instance, by studies on sex specificity in childhood play behavior [6]. Some of the sex-related differences have also been documented in heterosexual and non-heterosexual individuals. Specifically, it has been shown that, on average, homosexual men tend to show several sex-atypical, i.e. feminine, psychological characteristics. For example, it has been reported that homosexual men exhibit higher empathy and lower physical aggressiveness than heterosexual men [7]. Also, homosexual men outperform their heterosexual counterparts in verbal associations, while the opposite pattern has been found in spatial abilities, particularly in mental rotations [8].

In the present study, we found a modulating effect of sexual orientation on differences between men and women in olfactory performance. Namely, in odor identification, heterosexual men were outperformed by all other participants, and, in odor discrimination, by non-heterosexual men. However, when separate regression analyses were run for each sex in which, along with sexual orientation, CGN was entered as a predictor, only the latter turned out to significantly predict performance on some of the olfactory tests. To be specific, in men, those who had been less gender-conforming in childhood exhibited a better ability of odor identification than the more gender-conforming ones, irrespective of their sexual orientation. In women, those who had been more gender-conforming in childhood exhibited greater olfactory sensitivity than the less gender-conforming ones, irrespective of their sexual orientation. Thus, it would seem that it is CGN rather than sexual orientation that actually modulates differences in olfactory abilities between men and women.

In conclusion, the present study accentuates the need to employ more comprehensive quantitative measures of sex-atypicality that are known to covary with sexual orientation, such as CGN, to acknowledge the full range of intrasexual variability in traits in which sex differences have been reported. In the present case of olfactory abilities, in which marked differences between men and women are typically noted, the variability observed in various measures was not limited to differences between male and female or heterosexual and non-heterosexual participants. The measure of CGN has afforded finer discrimination of individual performance on some tasks on the basis of recalled childhood sex-atypicality. At the same time, this study is, to the best of our knowledge, the first to demonstrate the effect of CGN and sexual orientation on olfactory abilities.

 

Source:

http://doi.org/10.1371/journal.pone.0080234