Sex Differences in Face Looking Preferences at Birth

Abstract

While sex differences in behaviour have attracted considerable scientific interest, their underlying causes are complex and remain poorly understood. One approach to understand whether early biological factors might play a partial role is to study newborns, who have limited postnatal experiences. Previous research on neonatal sex differences is extremely limited, and studies that do exist have yielded mixed results, raised methodological concerns, and are yet to be replicated. To assess these gaps, the present study aimed to reevaluate sex differences in neonatal social attention. 130 neonates (67 males, 63 females; mean age=33 hours) were presented with a video of a human face and a non-social object. On average, females allocated a greater percentage of time looking at the face relative to males (d=0.40). When analysing absolute looking times, females showed a preference for the face compared to the non-social object, while males showed no preference for either. Since sex differences in attention patterns are present from the earliest days of life, it is possible that it may emerge partially due to prenatal factors (e.g., sex hormones). However, alternative explanations for these findings may be that these differences reflect general maturational differences between males and females or arise from low-level visual properties of the stimuli rather than their social versus non-social content.