Springer Nature: Scientists show that boys and girls perceive the world differently from the first hours of life

Psychologists at the University of Cambridge have shown that sex differences in attention are detectable from birth: newborn girls spend more time looking at human faces, while boys spend more time looking at objects. The study, involving 130 infants, was published in the journal Biology of Sex Differences.

Within the first few hours after birth, the babies were shown two videos side by side: a moving human face and a Newton’s cradle — a set of suspended metal balls that swing under the force of gravity. All the infants, regardless of sex, looked at the face more often. However, on average, girls devoted a greater proportion of their viewing time to the face, while boys spent longer watching the balls.

Because the experiment was conducted just hours after birth, before the infants had any significant life experience or exposure to social expectations, the researchers suggest that the differences were rooted in prenatal factors, including hormone levels and genes.

The new study replicates research conducted by Cambridge psychologists in 2000, which no one had attempted to repeat for more than two decades because experiments involving newborns are particularly difficult to conduct. The earlier study found the same pattern. This time, however, the researchers used stricter methods: the infants’ gaze was tracked using a more reliable technique, while the videos were analyzed by specialists who did not know either the sex of the infant or which stimulus the infant was viewing. This helped eliminate the possibility that researchers’ expectations could unintentionally influence the results.

At the same time, the scientists caution against drawing overly simplistic conclusions. “These differences do not apply to every boy or every girl: they are visible only when comparing groups on average. There is considerable variation and overlap within each sex,” said researcher Carrie Allison. The same team previously showed that differences in brain structure are also established before birth; the new findings add differences in attention and behavior to the picture.

The researchers hope that understanding the origins of the earliest sex differences will help shed light on neurodiversity and autism, which is diagnosed approximately twice as often in boys as in girls. The team is now conducting a longitudinal follow-up of the participants to determine how these early differences may affect development later in life.