Newborn gaze study revives evidence of sex-linked attention differences

A tightly controlled study of 130 babies found average differences in attention within hours of birth, while stressing that the pattern does not define individual children.

Cambridge researchers say they have found evidence that some sex-based differences in attention are present within hours of birth, adding weight to the view that biology may shape early development alongside experience. In a study of 130 newborn babies published in Biology of Sex Differences, the team found that, while infants of both sexes tended to prefer a social stimulus, female babies on average spent more time looking at a human face, whereas male babies on average devoted more attention to a non-social object.

The finding revives and updates earlier Cambridge work from 2000, which reported a similar pattern but was difficult to replicate for more than two decades because newborn studies are demanding to carry out. According to the university, the new experiment used tighter controls than the original, including more reliable gaze-tracking and blinding of the researchers who reviewed the footage so they did not know the sex of the baby or what the infant was looking at. The babies were tested at an average age of about 33 hours after birth, with the researchers presenting side-by-side videos of a moving face and a Newton’s cradle-style object.

The researchers argue that the timing of the effect matters. Because the babies had had so little postnatal exposure to gendered expectations, the team says prenatal factors such as hormones or genetics may help explain the average difference. Yumnah Khan, the lead researcher, said the new work fits with earlier Cambridge findings that sex differences in brain structure are also present at birth. Simon Baron-Cohen, who supervised the study, said the results suggest “nature and nurture, not nature or nurture”.

The researchers were careful to stress that the result describes group averages, not fixed traits in individual children. Carrie Allison said the differences do not apply to all boys or all girls and that there is substantial overlap between the sexes. The team is now following up with longer-term research to see whether these early attention patterns are linked to later development in thinking, behaviour and social skills, including in autism, which is diagnosed more often in boys than in girls. The study was supported by the Wellcome Trust, the Simon Foundation Autism Research Initiative, Trinity College Cambridge, the Cambridge Trust and the K. Lisa Yang Centre for Autism Research at Cambridge.