The short version
- A study of newborns found that girls spent more time looking at human faces than boys did when presented with side-by-side videos.
- Researchers attribute these early differences to biological factors such as genetics and prenatal hormone exposure rather than social conditioning.
- The findings may help explain why certain developmental milestones and neurodivergent conditions show different prevalence rates between sexes later in life.
A new study involving newborn infants suggests that differences in visual attention between boys and girls may be present from birth, offering fresh insight into the long-standing debate regarding biological versus environmental influences on behavior. Researchers at the University of Cambridge observed that female babies spent a proportionally greater amount of time watching videos of human faces compared to male babies, who showed relatively more interest in mechanical toys. Because the participants were only hours or days old, the findings imply that these attentional preferences are likely driven by innate biological factors rather than learned social experiences.
The experiment involved one hundred and thirty infants ranging from eight hours to three days of age, all tested at the Rosie hospital in Cambridge. Each baby was settled on a parent’s lap while watching a laptop screen displaying two simultaneous video clips: one featuring a young woman’s face and the other showing a Newton’s cradle toy swinging back and forth. An eye-tracking device monitored where each infant looked during the presentation. While both groups of babies showed a general preference for the human face over the mechanical object, the female infants demonstrated a significantly stronger bias toward the face than their male counterparts.
Yumnah Khan, a PhD student at the Autism Research Centre who led the research, noted that the study highlights how early certain behavioral distinctions emerge. The findings were published in the journal Biology of Sex Differences and contribute to an active scientific discussion about the origins of sex-based differences. Since the infants had not yet been exposed to significant cultural or social conditioning, researchers point to biological variables as the primary drivers. These include genetic factors and differential exposure to testosterone in the womb, with male fetuses typically experiencing more than twice the level of this hormone compared to females during the first two trimesters.
It is important to note that the study identifies average differences between groups rather than universal traits for all individuals of a specific sex. The researchers emphasized that there was considerable variation and overlap between boys and girls, meaning these trends do not apply to every single infant. Small initial differences in attention are unlikely to dictate an individual’s entire developmental trajectory, but they may contribute to broader patterns observed as children grow. For instance, girls often learn to speak earlier than boys and develop certain social skills at a younger age, potentially facilitated by this heightened early interest in social stimuli.
The implications of these findings extend beyond typical development into the realm of neurodevelopmental conditions. The Cambridge team is investigating whether subtle biological differences present at birth correlate with varying vulnerabilities to psychiatric disorders later in life. Conditions such as autism and attention-deficit/hyperactivity disorder are diagnosed more frequently in males, whereas anxiety and depression are more common in females. Understanding the root causes of these disparities requires examining how early attentional biases might influence brain development and social engagement over time.
Previous research has already identified sex-based differences in brain structure at birth, which are also thought to be influenced by prenatal hormonal environments. This new study adds behavioral evidence to that anatomical data, suggesting that the hardware of the brain may be accompanied by software-like preferences from the very start of life. However, the researchers caution that these early observations are only a starting point. Further longitudinal studies are needed to track these infants as they become toddlers and older children to determine if these initial attentional differences persist or evolve.
The debate over nature versus nurture remains complex and often contentious within the scientific community. This research does not resolve the entire puzzle but provides a specific data point indicating that at least some behavioral distinctions are established before socialization begins. By isolating biological factors through testing newborns, scientists can better separate innate predispositions from environmental influences. This approach helps clarify how early life experiences interact with biological baselines to shape human development.
As the field continues to explore these questions, the focus remains on understanding the mechanisms behind sex differences without overstating their significance for individual outcomes. The study underscores the importance of recognizing both biological realities and individual variability. Future work will likely aim to connect these early attentional patterns with long-term developmental trajectories, offering a more comprehensive view of how human behavior emerges from the interplay of genetics, hormones, and environment.
Sources behind this briefing
Go to the original reporting
- The Guardian US↗Baby girls’ greater interest in faces offers clue to nature v nurture debate
