Newborn girls demonstrate a greater ability to pay attention to human faces compared to newborn boys, according to a study published in the journal Biology of Sex Differences. The research, which tested 130 infants within hours of birth, aimed to identify potential biological differences in attention skills before social influences could play a role.
Scientists presented the newborns with two videos simultaneously: one of a human face and another of a Newton's Cradle. The study found that while both sexes showed a preference for the human face, girls spent a significantly larger proportion of their time gazing at the social stimulus. Boys, on average, spent more time looking at the moving object.
According to Professor Sir Baron-Cohen, Director of the Autism Research Centre and a supervisor of the study, these findings, observed so soon after birth, suggest that prenatal factors may contribute to these observed sex differences. "The fact that we observe these differences within hours of birth, before extensive postnatal experience has occurred, suggests that prenatal factors play a role," Baron-Cohen stated. "In other words, it’s nature and nurture, not nature or nurture."
This new research builds upon a 2000 study that also indicated differences in newborn attention, with boys looking more at objects and girls at faces. However, that earlier study faced methodological criticisms, including the use of the lead investigator as social stimuli, which could have biased the results. The current study employed a more rigorous approach, using videos of an unrelated person and a moving object, and blinding the researchers measuring eye gaze to the infants' sex and the stimuli being observed to prevent bias.
The researchers caution against overgeneralizing the findings, emphasizing that the differences were observed on average at the group level and do not predict individual behavior. Lead author Yumnah Khan, a PhD student at the Autism Research Centre, stressed that "it's not nature or nurture, but rather nature and nurture." She added that while the findings suggest a potential role for biological factors present at birth, further research is needed to confirm this link.
The study's implications for understanding developmental trajectories and conditions like autism, which is diagnosed more frequently in boys, are a key area of interest. Khan noted that these early differences might help explain phenomena such as faster language acquisition in females, potentially linked to heightened social interest from birth. A longitudinal study is currently underway to explore these connections further over time.