No abstract

Face perception skills are fundamental to social cognition, yet they vary markedly across individuals. This diversity has stimulated controversy over the relative contributions of genetic factors, prenatal environment, and postnatal experience to face perception. Recent twin studies have found that face perception is heritable, highlighting the potential for substantial prenatal determination of these skills. In contrast, previous work on potential influences of the prenatal hormonal environment on social cognition have found no association between 2D:4D, a marker for prenatal androgen exposure, and processing of facial emotional expressions, apparently precluding a major role for prenatal hormones in governing face perception. We propose that substantial predictive relationships between 2D:4D and face perception may have been masked in previous work because the task employed required both face perception and processing of others' emotions, the latter component being greatly influenced by circulating hormones in adults. To assess prenatal hormone influences on face perception without requiring emotion processing, we related 2D:4D to the face inversion effect (FIE), a measure of the recruitment of specialist face processes to visual perception. The magnitude of the resulting predictive relationship (r 0 .52) compared surprisingly well with that found between identical twins' face perception (rs 0 .27-.61), suggesting that mechanisms of 2D:4D may account for a substantial proportion of perinatal influences on face processing. Furthermore, we employed 2D:4D as a common scale to map individual differences in the FIE onto prenatal testosterone:estrogen ratios, assayed by Lutchmaya, Baron-Cohen, Raggatt, Knickmeyer, and Manning (Early Human Development 77:23-28, 2004). The substantial overlap between the two data sets further implicates prenatal steroids in adult face perception skills.Keywords Face perception . Visual working memory . Testosterone . Prenatal sex steroids . 2D:4D . Digit ratio A face conveys important information about an individual's identity, age, ethnicity, gender, and emotional state, key characteristics that guide social interaction. Intriguingly, despite its universal importance, human expertise at distinguishing subtle variations in faces differs strikingly between individuals (e.g., Bowles et al., 2009;Wilhelm et al., 2010), although the mechanisms responsible for this diversity remain to be elucidated. While postnatal experience undoubtedly fine-tunes face perception (McKone, Kanwisher, & Duchaine, 2007;Webster, Kaping, Mizokami, & Duhamel, 2004), some of the most profound effects likely reflect an individual's biology-in particular, genetic factors and the uterine environment in which early brain development takes place. Two recent studies (Wilmer et al., 2010;Zhu et al., 2010) have found that face-specific aspects of perception correlate more highly in monozygotic (identical) than in DZ (fraternal) twins, suggesting that face processing is heritable. Additionally, prenatal expos...