Who are you thinking about? The fMRI knows

Think about your mother. Now think about your best friend. Now think about your favorite teacher. Each of those thoughts produced a distinct, interpretable pattern of activity in your brain, suggests new research by Cornell University psychologist Nathan Spreng, PhD.

In the study, published in March in Cerebral Cortex, Spreng and colleagues asked 19 young adults to learn about four people. Each protagonist profile included a name, photograph and 12 statements that described aspects of the protagonist's personality.

Next, the researchers asked participants to imagine how the four protagonists would behave in different settings — for example, what would each do if he or she were in a bar and someone spilled his or her drink? The participants imagined these vignettes for 10 seconds as they lay in an fMRI scanner.

When Spreng and his colleagues examined the scans, they were able to identify which protagonist the participant was thinking about based on the pattern of activity in the participant's medial prefrontal cortex. They also found that areas of the cortex seemed to code for different personality traits, such as agreeableness and extraversion.

Such research, Spreng says, will help scientists understand how people successfully navigate social situations, because learning about other people and predicting how they will behave in different circumstances is a key part of that navigation.

"We're really trying to understand the neural mechanisms behind how we have this inner world," Spreng says. "We spend a lot of time thinking about other people, yet scientists don't understand these processes very well."

The research could also lead to a better understanding of disorders in which such abilities are impaired, like autism, he says.

Spreng hopes to extend the research to look at how people form representations of real people in their lives, such as family members and friends.

—Lea Winerman