How the brain reads body language to help people work together

In sports, a team is said to have good "chemistry" when they play well together and get along on and off the court. Players who have played with each other for a long time can anticipate each other's moves, supposedly giving them an edge over equally talented, but less cohesive opponents.

This might sound like a clich thrown around by TV announcers, but according to new behavioral neuroscience research from the University of Chicago Medicine, there is something to this idea. Researchers asked people to predict the intentions of someone performing everyday tasks, like reaching for a bottle of water. The study participants were much better at predicting the outcome-be it picking up the bottle to take a drink, pouring it in a glass, or offering it to someone else-when the person they were watching was their significant other instead of a stranger.

"We learn so much from body language. And for couples, the more you relate to one another, the faster you can coordinate your actions," said Stephanie Cacioppo, PhD, assistant professor of psychiatry and behavioral neuroscience, who led the study. "This can include any significant relationship like family, sports teammates or co-workers. The more you think of yourself as a unit, the better you can predict each other's intentions."

The social self

An important part of identity is a sense of our "social self," which includes our core values, beliefs, emotions and expertise. This social self can extend to our social groups and include others who share a similar identity. When we're with significant others, we tend to include them in our personal social self, expanding that identity to a combined unit (i.e. married people think of themselves as a couple rather than two individuals).

In the brain, this means we have shared mental representations of ourselves along with our significant others. This is represented in what's called the mirror neuron system, which comprises neurons that fire both when a person acts and when you see the same action performed by someone else. It mirrors the action, in other words, as if you are also performing the action instead of just watching.

In the new study, Cacioppo and her colleagues used functional MRI scans to record brain activity from 24 people while they looked at a series of photos showing someone reaching for a bottle of water, then grasping it, and then finally revealing their intentions (i.e. pouring it in a glass, taking a drink, etc). Some of the photos showed that person's significant other reaching for the objects, and some showed a stranger. The results showed that participants were better at predicting what would happen in the last photo if it showed their significant other than if it was a stranger. Interestingly, this better performance was associated with greater activation in the mirror neuron system.

In addition, the more the participants reported being close to their partner, the less the brain areas associated with distinguishing one's own actions were recruited. That is, the more the observer and the actor share a common mental map or social self, the smaller the differences in brain activity to one's own actions and the actions of the other person.

Cooperation and teamwork

Cacioppo said these shared mental representations of our significant others make it easier for people to cooperate, while requiring us to use less mental energy to read body language and understand what each other is doing. Picture parents getting their kids ready for school. If one reaches for the cabinet door where the lunch bags are stored, the other automatically knows to start getting out bread, peanut butter and jelly for sandwiches.

"Although we are all interdependent to some degree, the notion of social self highlights the extent to which partners, friends and family members who feel connected to one another share a common social self," Cacioppo said. "This shared 'transactive' mental map explains why a significant other is often easier to read," she said.

"This increased facility makes it simpler to align interests, goals and behaviors within the couple, thereby promoting cooperation and behaviors that promote mutual benefit, like parenting."

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The study, "Predicting Intentions of a Familiar Significant Other Beyond the Mirror Neuron System," was published in Frontiers in Behavioral Neuroscience. Additional authors include Elsa Juan from the University of Geneva, Switzerland, and George Monteleone from the University of Chicago.