Even the crankiest curmudgeon relies on a certain level of social skills just to get through the day. You may not consider yourself particularly social — or even particularly empathetic! — but since age 4 or so, you’ve nevertheless been honing an ability that helps you to navigate your way through pretty much any social interaction: the capacity to mentalize, or read another person’s mental and emotional state of mind.
Psychologists call this vital skill “theory of mind,” or the ability to attribute thoughts and beliefs to others. Theory of mind is what makes us aware of our own selves and what distinguishes us from others, and helps us understand that others can experience the world differently from the way we do. It’s the reason you can understand what someone is thinking, and anticipate what they’re going to do or say next. (Some people with neurodevelopmental disorders lack a fully developed theory of mind, and therefore struggle with this understanding). And in a study recently published in the journal Nature, a team of scientists may have found where this ability lives in the brain.
To understand how theory of mind develops, researchers at the Max Planck Institute for Human Cognitive and Brain Sciences analyzed images of the brains of 43 kids between the ages of 3 and 4, looking at connectivity in the brain’s white matter in relation to the children’s performance on a type of test called the “false-belief test.” False belief — or the understanding that another person’s belief is different from reality — has been used in the past as a way of measuring theory of mind in kids. In one popular version, for example, a child is shown a chocolate box that contains crayons instead of candy, then asked what they think another child thinks is inside the box; if their theory of mind is well-developed, they’ll understand that the newcomer will expect chocolates.
In this latest study, the author found that theory of mind developed in conjunction with white matter in certain parts of the brain: “That is, 4-year-old children have more mature white matter in these regions and better theory-of-mind abilities than the 3-year-olds,” lead author Charlotte Grosse Wiesmann explained. “This relation is specific to theory-of-mind abilities and cannot be explained by developments in other cognitive domains, such as children’s linguistic abilities, general intelligence, or executive functions.”
The study authors also found a link between theory of mind and increased connectivity between two brain regions: the temporoparietal junction, which is involved in thinking about others, and the inferior frontal gyrus, a region in the frontal lobe which supports thinking about abstract concepts such as belief and reality. As these connections become stronger, so, too, does a kid’s ability to empathize, pick up nonverbal cues, and realize that another person’s intentions may not necessarily be in their own best interest — in other words, to understand the social interactions, large and small, that will happen every day of their life.