Gene-environment interactions in face categorisation: experience with a nanny and oxytocin receptor genotype interact to reduce face categorization reaction times

Human faces are relevant stimuli that capture attention, provide information about group belonging and elicit automatic prepared responses. While early experiences with other race faces plays a critical role in acquiring face expertise, the exact mechanism through which it exerts its influence is still to be elucidated. In particular, the influence of genetic factors and the role of a multi-ethnic context has not been explored. The aim of this study was to investigate how caregiving experiences with nannies and oxytocin receptor gene (OXTR) genotypes interact in regulating other-race categorisation mechanisms in adults. Information about single nucleotide polymorphisms of the OXTR (rs53576) and experiences with own- and other-race nannies was collected from 89 Singaporean adults, who completed a visual categorization task of face stimuli (Chinese or Javanese). Participants were grouped into A/A homozygotes and G-carriers and assigned a score to account for the type of nanny experience. A General Linear Model was used to estimate the effect of nanny experience, genetic group and their interaction on categorization reaction time. A significant main effect of the nanny experience (p<.001) and of the interaction between genetic group and experience (p=.008) was found. Post-hoc analysis revealed a significant negative correlation between nanny experience and reaction time for A/A homozygotes (r=-0.52, p<.001) but no significant correlation for G-carriers. In summary, a significant gene-environment interaction on face categorization was found. This finding appears to represent an indirect pathway through which genes and experiences interact to shape mature social sensitivity in human adults. HighlightsEarly nanny experience interacts with oxytocin receptor genotype in affecting the speed of face categorisation. Individuals with other-race nanny experience show faster categorisation response times. Gene-environment interactions are present in face categorisation.