fMRI shows 3-year-olds have brain networks to understand others

A team of researchers at the Massachusetts Institute of Technology (MIT) used functional MRI (fMRI) to explore how young children develop an ability known as “theory of mind,” which allows one person to infer about another’s mental state.

Led by Hilary Richardson, an MIT graduate student and lead author of the study, the research was published online March 12 in Nature Communications.

“The brain regions involved in theory-of-mind reasoning are behaving like a cohesive network, with similar responses to the movie, by age 3, which is before kids tend to pass explicit false-belief tasks,” said, to MIT.

The team studied 122 children between 3 and 12 years old for four years. The children watched a short video that included social interactions intended to stimulate specific areas of the brain. Each participant underwent a complete fMRI of the brain, focusing on the theory-of-mind network and the brain’s pain matrix, which can be activated when thinking about another person’s mental state. Richardson and colleagues also scanned 33 adults to compared results.

“We see early signatures of this theory-of-mind network being wired up, so the theory-of-mind brain regions which we studied in adults are already really highly correlated with one another in 3-year-olds,” Richardson said.

The activity in younger children was not as pronounced as that in older children and the adults. But the responses increased in strength with age.

“Scientists have focused really intensely on the changes in children’s theory of mind that happen around age 4, when children get a better understanding of how people can have wrong or biased or misinformed beliefs,” said Rebecca Saxe, senior author of the paper and an MIT professor of brain and cognitive sciences. “But really important changes in how we think about other minds happen long before, and long after, this famous landmark. Even 2-year-olds try to figure out why different people like different things—this might be why they get so interested in talking about everybody’s favorite colors.”