How infants’ brain decodes social behaviour

Infants' brains can understand what they are observing and thus can copy other people's action, finds a new study providing the first evidence that directly links neural responses from the motor system to overt social behaviour in infants.

Babies understand what they are observing. There is a direct connection between observing others, understanding what others are doing, and learning how to act abilities which are often disrupted in developmental disabilities, including autism, the researchers said.

Like adults, infants show this response when acting themselves and when watching others' actions, suggesting that the motor system of babies may play a role in the perception of others' actions, the researchers pointed out.

"Our research provides initial evidence that motor system recruitment is contingently linked to infants' social interactive behaviour," said lead author Courtney Filippi, doctoral candidate at the University of Chicago in the US.

The findings showed that recruiting the motor system during action encoding predicts infants' subsequent social interactive behaviour, the researchers stated.

"This understanding on the part of a baby involves not just seeing the other person's action, but also involves the baby's own motor system, which is recruited when he or she chooses the same toy," said Helen Tager-Flusberg, professor at Boston University in the US, who was not involved in the research.

The study, published in the journal Psychological Science, showed that by the middle of their first year of life, babies begin to understand that people act intentionally.

"Here we looked at the development of social cognition, social behaviour, and the motor system, all of which are critical for human development and are often disrupted in developmental disabilities, including autism," explained co-author Amanda Woodward, professor at the Chicago University.

For the study, the team involved 36 seven-month-old infants, whose brain activity was measured using electroencephalography (EEG), during an experiment, where each infant had to observe a person reaching out to a toy.

Babies' brain activity predicted how they would respond to the person's behaviour. When the infants recruited their motor system while observing the person grasp the toy, they subsequently imitated him. When they didn't imitate the person, there was no detectable engagement of the motor system in their brain activity as they watched him.