Sex discriminations made on the basis of ambiguous visual cues can be affected by the presence of an olfactory cue.

Graeme Hacker,Anna Brooks,Rick Van Der Zwan

doi:10.1186/2050-7283-1-10

Abstract

BackgroundAlmost every interpersonal interaction is mediated by the sex of the individuals involved. Visual, auditory, and olfactory cues provide individuals with the opportunity to discriminate the sex of others from a distance and so prepare sex-appropriate behaviours for any impending interaction. The usefulness of that important social skill is mediated by the reliability of the sensory information. Sometimes cues in one domain will be ambiguous, and the perceptual processes mediating sex perceptions will need to integrate information from across the senses for better reliability. With that in mind, the experiment reported here was designed to explore the effect of olfactory-visual interactions on sex perceptions.MethodsObservers were presented visually with point-light walkers that were sexually ambiguous (not unequivocally female or male). They were asked to judge, using a two-alternative forced choice paradigm, the sex of each walker. Tested on two occasions, observers unknowingly made sex judgements in the presence or absence of pads soaked in male sweat.ResultsThe presence of male sweat was associated with higher proportions of ‘male’ judgements of both ambiguous female and ambiguous male walkers (F1,19 = 24.11, p < 0.01).ConclusionThese findings suggest that olfactory cues can modulate visual sex discriminations made on the basis of biological motion cues. Importantly, they seem to do so even when the olfactory cue is not consciously perceived, suggesting these effects are mediated by perceptual rather than cognitive processes.These findings suggest that there exist cortical processes mediating sex perceptions that are capable of integrating visual and olfactory information. What is important is that this sensory integration takes place without conscious knowledge and that appropriate behaviour modifications may occur automatically.

Highlights

Almost every interpersonal interaction is mediated by the sex of the individuals involved
The mean proportion of times the ambiguous male was judged, in the absence of olfactory cues, to be male was 0.61 ± 0.05. Both proportions increased in the presence of the olfactory cue: In the presence of male sweat the mean proportion of times the ambiguous female walker was judged to be male was 0.25 ± 0.05, an increase of 8%
The experiment reported here tested the hypothesis that olfactory cues contained in male sweat would be used, by observers, to mediate sex perceptions of sexually ambiguous walkers

Summary

Introduction

Almost every interpersonal interaction is mediated by the sex of the individuals involved. Work using various types of stimuli suggests the existence of “sex tuned” neurons (Jordan et al 2006; Little et al 2005; Troje et al 2006), at least some of which are multi-sensory [see Eagleman 2001; Shimojo & Shams 2001; Kovacs et al 2004; van der Zwan et al 2009)]. Of those studies two are interesting in the present context. (van der Zwan et al 2009) combined unambiguous auditory sex-cues with ambiguous visual sex-cues to show perceptual integration: The sound of female footsteps made sexually ambiguous point-light walkers (Johansson 1973) appear more often to be female (van der Zwan et al 2009)

Methods

Results

Conclusion