A preschooler is shown a set of cards and asked to sort them by colour. Once the child gets used to the game, the instructions change: now the cards must be sorted by shape. A little later, the rules change again, and the child has to keep switching between the two.For a young child, this is not as simple as it sounds. They have to stop following a rule they have just learnt, remember the new instruction and apply it correctly. This ability to adjust thinking when a situation changes is known as cognitive flexibility.
8 Oct 2026 | 14:25
What is the hardest part of raising a toddler that nobody prepared you for?
Now, researchers have found an unexpected association with this skill: how often a child naturally blinks.A study published in Communications Psychology found that preschoolers who blinked more frequently tended to perform better when asked to switch between different sorting rules. The researchers also found a link between blink frequency and activity in a specific region of the brain involved in executive function.The study, “Emergent blink rate in early childhood is associated with neural origins of executive function,” examined 113 Japanese children aged 35 to 80 months.
What did researchers ask the children to do?
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The children took part in a card-sorting game called the Dimensional Change Card Sort task. Initially, they had to match cards according to colour. Then the researchers changed the instruction and asked them to sort the same type of cards according to shape. In another stage, the children had to alternate between the two rules.This tested whether they could move away from a familiar instruction and adapt when the task changed. While the children completed the activity, researchers recorded their natural eye-blink rate using a camera. They also monitored brain activity using functional near-infrared spectroscopy (fNIRS), a non-invasive technique that measures changes in blood oxygen levels in the brain.The results showed that children with higher spontaneous blink rates tended to achieve better accuracy when switching between rules. The association remained even after researchers accounted for the children’s age, suggesting that the finding was not simply because older preschoolers both blinked more and performed better.However, the relationship was modest. It does not mean that every child who blinks frequently will be better at changing tasks.
What does blinking have to do with mental flexibility?
The researchers were interested in blinking because earlier research has linked natural eye-blink frequency with brain systems involved in alertness, attention and dopamine activity.Dopamine is a chemical messenger that helps regulate several brain functions, including motivation, learning and cognitive control. These systems are also involved in executive function, a group of mental abilities that includes holding information in mind, controlling impulses and adapting to changing instructions. These skills develop rapidly during the preschool years. The brain’s prefrontal cortex, located behind the forehead, plays an important role in this development.The new study found that children who blinked more frequently also showed greater activity in the right dorsolateral prefrontal cortex, a region involved in cognitive control. Activity in this area was also associated with better performance on the rule-switching task.The researchers suggest that natural blink rate may offer a simple, non-invasive way to study aspects of early brain development. It could help researchers investigate how executive function develops without relying on complicated procedures that are difficult to use with young children.
Does blinking more mean a child is smarter?
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The answer is no. The researchers specifically caution against interpreting the findings as a measure of intelligence. The study examined one part of executive function: cognitive flexibility. It did not test overall intelligence, academic ability or a child’s general learning potential.It also does not show that blinking more improves mental flexibility. The researchers measured blink frequency and task performance at one point in time, so they cannot establish that one causes the other.Blinking is influenced by several factors, including alertness, the surrounding environment and other brain processes. Some children who blink less may still have strong cognitive abilities.The researchers also point out that the association was not strong enough to assess an individual child’s development accurately. Eye-blink frequency should not be used by parents or teachers to judge a child’s intelligence, attention span or readiness for school.
What parents should take away from the findings
For parents, the study is an interesting reminder of how many mental skills are developing during the preschool years. A child who struggles when instructions suddenly change may simply need more practice with tasks that require them to stop, think and adapt.Simple activities can give children opportunities to practise this ability. Parents can ask them to sort toys first by colour and then by size, change the rules of a matching game or play activities in which they must respond differently to different instructions.The study offers a new clue for researchers trying to understand early brain development. But for now, a child’s blinking is not a scorecard for their mental abilities. What matters is that cognitive flexibility develops gradually, and children can show it in different ways as they grow.
