Recent studies have suggested the existence of human sex pheromones, with particular interest in two human steroids: androstadienone (androsta-4,16,-dien- 3-one) and estratetraenol (estra-1,3,5(10),16-tetraen-3-ol). The current study takes a critical step to test the qualification of the two steroids as sex pheromones by examining whether they communicate gender information in a sex-specific manner. By using dynamic point-light displays that portray the gaits of walkers whose gender is digitally morphed from male to female [1, 2], we show that smelling androstadienone systematically biases heterosexual females, but not males, toward perceiving the walkers as more masculine. By contrast, smelling estratetraenol systematically biases heterosexual males, but not females, toward perceiving the walkers as more feminine. Homosexual males exhibit a response pattern akin to that of heterosexual females, whereas bisexual or homosexual females fall in between heterosexual males and females. These effects are obtained despite that the olfactory stimuli are not explicitly discriminable. The results provide the first direct evidence that the two human steroids communicate opposite gender information that is differentially effective to the two sex groups based on their sexual orientation. Moreover, they demonstrate that human visual gender perception draws on subconscious chemosensory biological cues, an effect that has been hitherto unsuspected.
Bibliographical noteFunding Information:
All experimental procedures were approved by the Institutional Review Board at the Institute of Psychology, Chinese Academy of Sciences. We thank Nikolaus F. Troje for kindly providing us with the visual stimuli and Yuting Ye for assistance. This work was supported by the National Basic Research Program of China (2011CB711000), the National Natural Science Foundation of China (31070906), the Knowledge Innovation Program (KSCX2-EW-BR-4), and the Strategic Priority Research Program (XDB02010003 and XDB02050001) of the Chinese Academy of Sciences.