Considering Intentions of Others Tied to Structural Brain Changes

New research finds that a teenager’s ability to consider the intentions of others in regard to gauging fairness may be linked to structural changes in the brain’s cortex. These changes most likely show a synaptic reorganization in how brain regions connect and communicate with one another.

Deciphering the intentions of others is vital to human interaction and cooperation within society. Previous research has shown that areas of the social brain linked to how we care about others or “social inference,” continue to undergo cortical development until late adolescence.

The new study, published in the journal Scientific Reports, is the first to provide evidence linking structural changes with behavioral changes in the context of fairness.

For the study, participants aged nine to 23 played an ultimatum game based on the exchange of money. First, participants who played the role of “proposer” were told to select between two different ways of dividing $10. Those who acted as “responders” then decided whether to accept or reject the chosen division.

Using computational modeling, the researchers at Dartmouth College observed how participants used two different cognitive strategies while making their decisions. Then they analyzed how these processes correlated with measurements of participants’ cortical thickness, which they obtained through magnetic resonance imaging (MRI).

The researchers found that younger players tended to want to minimize the difference in the division of the money, making it so that everyone gets the same amount. However, the older the participants were, the more likely they were to consider the other players’ intentions.

This change from a simple rule-based egalitarian strategy to a more sophisticated strategy that considers both the other players’ intentions and notions of reciprocity, was observed during late adolescence.

This gradual shift coincided with cortical thinning in the brain, specifically, in areas of the dorsomedial prefrontal cortex, which is involved with how we view others’ mental states, and the posterior temporal cortex, which is involved in visual perception particularly in processing facial information.

“This work provides converging evidence in line with other research that the computation of inferring intentions is processed in the dorsomedial prefrontal cortex,” said senior author Dr. Luke Chang, an assistant professor in the Department of Psychological and Brain Sciences and the director of the Computational Social Affective Neuroscience Laboratory (Cosan Lab) at Dartmouth.

“We were surprised that this shift in preference for considering others’ intentions occurred so late in development. Of course, younger children can infer the intentions of others, but we see that this ability continues to be refined well into late adolescence.”

“This finding has potential implications regarding how much autonomy this age group should be given when making important social and ethical decisions, such as purchasing weapons, going to war, and serving on juries,” added Chang.

Source: Dartmouth College