An international team of researchers from the French National Institute of Health and Medical Research (Inserm) and the National University of Singapore set out to address this gap. They utilized data from the Singaporean cohort study GUSTO (Growing Up in Singapore Towards Healthy Outcomes), which has tracked children since birth. The scientists analyzed parental reports on screen time at six different ages—ranging from 1 to 8 years old. Several years later, they assessed the academic performance and working memory of these same children at ages 9 and 10.5, respectively. The study sample included 502 children.
The results were unexpected: it turned out that *when* screen time occurs matters more than *how much* there is. Children who spent significant time in front of screens did indeed demonstrate lower academic performance and weaker working memory at older ages. However, this association was distributed very unevenly across different ages.
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The most significant negative effect was observed in relation to screen time at the age of one. This aligns with findings from other recent studies linking early screen exposure to the accelerated maturation of brain networks responsible for visual perception and cognitive control.
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No significant link was found between screen time and future academic performance at ages two and three.
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However, the negative correlation reappeared at age six—precisely when children start school.
What does this mean for educators and parents?
The authors’ hypothesis is that early infancy (the first year of life) and the start of formal schooling represent windows of heightened sensitivity. In the first instance, the developing brain is particularly vulnerable because screen time displaces live emotional and verbal interaction with an adult. The issue is not radiation, or even the content itself, but rather what *didn't* happen instead of watching a cartoon: play, conversation, physical contact, and exploration of the physical world. By age six, the role of screens shifts; they can interfere with concentration and the development of skills essential for systematic learning.
The authors emphasize that a single extra hour of screen time a day won't harm a specific child; the statistical effect is small. However, at a population level—across an entire country or even a city—such a shift could move a significant number of children into a group with lower cognitive performance.
Note for practitioners: The World Health Organization and the American Academy of Pediatrics recommend completely avoiding screens for children under 18–24 months and limiting screen time to one hour a day for children aged two to five. Yet, studies show that children's actual screen time far exceeds these guidelines.
What’s next?
The study does not address questions regarding content quality, device type, or whether the child is viewing the screen with a parent or alone. As the authors themselves note, this is the next step; duration alone does not tell the whole story. Nevertheless, the practical takeaway is clear: a "less is better" strategy should begin in infancy, and supervision should not be relaxed when a child starts school.