News Release

How self-control develops in the brain

Young children find it more difficult than adults to resist impulses. Between the ages of three and four a central brain network for self-control matures.

Peer-Reviewed Publication

Max Planck Institute for Human Cognitive and Brain Sciences

As adults, we have the ability to control our own thoughts, emotions and behaviour. We have a kind of inner stop sign that allows us to pause and enables us to achieve even long-term goals. In early childhood, especially between the ages of three and four, a real jump in children's ability to control themselves can be observed. They learn to wait for certain things while also being able to concentrate on single things for a while.

But how does this breakthrough come about at preschool age? And does sitting still and concentrating require the same ability as resisting the impulse to eat tempting sweets all at once? These are the questions explored in a new study from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS), now published in the Journal of Neuroscience.

To investigate these developmental leaps, the researchers used a variety of tasks to test different forms of self-control. In the "bear-dragon game" they recorded the children's ability to suppress certain actions. In this game, the children are first introduced to two cuddly toys: the "dear bear" and the "bad dragon". During the game, the children receive various instructions from the two characters, such as "Clap your hands!" or "Touch your nose!" However, they were asked to carry out these instructions only when the "dear bear" told them to, and not when the "evil dragon" gave the instruction.

Another task, known as the "marshmallow test", again assessed the children's ability to suppress an emotional impulse for an extended period of time. In this task, the children sit at a table on which there are freely assessable gummy bears or candy bars. A larger portion of these, visible to the children, sit in a locked box. The experimenter tells the children she must now leave the room for a short time, but makes the following offer, "If you wait until I come back, without eating the candy, you'll get the larger portion."

As it turned out, the four-year-olds performed significantly better than the three-year-olds in both tasks, just as previous studies had shown. MRI scans also showed that the cognitive control network matures between the ages of three and four. The cerebral cortex becomes thicker. In adults this network determines how well we are able to control our impulses and actions. In its mature state it mainly comprises regions in the frontal and parietal lobes of the brain, which in turn are connected by nerve fibres and can thus exchange information quickly and efficiently.

The interesting thing here is that the different self-control tasks, the bear-dragon and marshmallow tests, were associated with different regions within the cognitive control network. If children did well in the former, the prefrontal cortex, which in adults is particularly responsible for planning and controlling actions, was more developed. If the toddlers did better on the marshmallow test, the supramarginal gyrus was more advanced in its maturation process, which is more associated with controlling attention.

"So, a gradual development might start in infancy, the result of which we only observe in fully developed self-control in adulthood," says Philipp Berger, a postdoc at MPI CBS and lead author of the study. "This also means that we may be able to influence this important ability at a very young age."

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