It’s complicated: A computer test uses an interactive story to gauge participants’ feelings of power and intimacy toward a group of fictional characters.

Brain regions that help people orient themselves in space and time may also guide their sense of intimacy and hierarchy with another person, according to findings presented Sunday at the 2013 Society for Neuroscience annual meeting in San Diego.

The researchers gauged participants’ sense of closeness and power in relation to six fictional characters using a 26-minute-long computer presentation that plays out like a choose-your-own-adventure game. The game establishes a ‘reference point’ for each character based on “the quick judgment you make of someone’s role relative to you,” says Rita Tavares, a postdoctoral fellow in the laboratory of Daniela Schiller at the Icahn School of Medicine at Mount Sinai in New York.

Tavares presented the findings at a nanosymposium at the conference. “In autism, one of the deficits may be that [people] have trouble tracking this social reference point,” she says. Tavares intends to use the test to study people with autism or other disorders linked to social deficits.

For this study, she and her colleagues used a functional magnetic resonance imaging scanner to measure brain activity in 18 adults as they followed along with the story.

The story takes each participant through a series of complex social interactions as his or her character navigates moving to a new town and looking for a job and a place to live. Participants meet and interact with characters who range from an old high-school friend, the boyfriend that friend recently split up with, a sleazy but influential older man and the female boss of the town’s big business. The various characters alternate randomly between male and female for each participant, but with an equal number of characters of each gender. 

Participants have 12 interactions with each character: 6 that determine power and 6 that determine intimacy. For example, on meeting the high-school friend, the test asks the participant whether she would give the friend a long hug or a brief pat on the back. Each time the participant interacts with a character, that character moves along a trajectory of greater, or lesser, intimacy or power, which is mapped as coordinates on a graph.

The program estimates a theoretical level of intimacy and power for each character, based on the participants’ answers. It then computes whether the participant is moving the character closer to or farther away from that point with each answer.

Three brains regions — the left hippocampus, the left parietal cortex and the dorsal anterior cingulate cortex — are more active when the character moves closer to the prediction, and less active when the character moves farther away. Each of these brain regions is known to play a role in determining an individual’s sense of space and time.

The researchers also gave the participants a personality test and a questionnaire that rates social anxiety. Participants whose activity in the hippocampus maps the best to the social predictions are also the least socially anxious and the least neurotic, the study found.

For more reports from the 2013 Society for Neuroscience annual meeting, please click here.