Neuroscientists
and developmental psychologists have found the first evidence that infants’
brains can process other people’s actions. That is, when infants watch other
people do things, their brains are actively engaged.
Specifically,
the innovative study provides the first evidence that directly links neural
responses from the motor system to overt social behavior in infants (such as
imitation).
The
study involved thirty-six seven month-old infants, who were each tested while
wearing a cap that used electroencephalography (EEG) to measure brain activity.
During the experiment, each infant observed an actor reach for one of two
toys.
Immediately
after, the baby was allowed to select one of the same toys. This procedure was
repeated 12 times.
Babies’
brain activity predicted how they would respond to the actor’s behavior. When
the infants recruited their motor system while observing the actor grasp one of
the toys, they subsequently imitated the actor. When they didn’t imitate the
actor, there was no detectable engagement of the motor system in their brain
activity as they watched the actor.
The
research will appear in Psychological
Science, the peer-reviewed journal of the Association for Psychological
Science.
“Our
research provides initial evidence that motor system recruitment is contingently
linked to infants’ social interactive behavior,” said lead author Courtney
Filippi, a doctoral candidate in developmental psychology at the University of
Chicago.
“It
provides initial evidence that recruiting the motor system during action
encoding predicts infants’ subsequent social interactive behavior.”
The
researchers used EEG to measure a component of brain activity that has been
linked to motor cortex activity in adults. Like adults, infants show this
response when acting themselves and when watching others’ actions, suggesting
that the motor system may play a role in the perception of others’ actions.
Until
the current study, however, this possibility had not been tested in infants.
“This
research tells us that, by the middle of their first year of life, babies are
beginning to be able to understand that people act intentionally — that they
choose one toy over another because they want that toy,” said Helen
Tager-Flusberg, professor of psychological and brain sciences at Boston
University.
“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.”
Fundamentally,
the researchers identified the neural processes that contribute to intelligent
social behavior in infants. And it’s the first evidence that motor system
activation in infants predicts the imitation of others’ actions, as well as an
apparent understanding of others’ goals.
“This
is big news, that babies understand what they are observing, that there is a
direct connection between observing others, understanding what others are doing,
and learning how to act,” said co-author Amanda Woodward, the William S. Gray
Professor of Psychology at University Chicago.
The
researcher’s methodology also broke new ground. “This is the first attempt to
combine the assessment of infants’ behavior — in this case, imitating the
actions of another person — with measuring brain activity in infants,”
Tager-Flusberg said.
The
task was not easy, however.
“Probably
the hardest place to study the relation between brain activity and behavior is
with infants, due to limitations in the methods that can be used, and the fact
that infants are infants,” Woodward noted. “Our methodology represents a
breakthrough and a proof of concept.”
“We’ve
worked hard over the years to develop the methods that allow us to record brain
activity from infants while they are engaged in the social world,” said
co-author Nathan Fox, University of Maryland, College Park.
“The
current research reflects our ability to synchronize brain and behavior in
infants during the first year of life.”
Although
this research will not translate directly into new medical treatments or
therapies, it could contribute to medical advances down the road by helping to
illuminate how the human brain functions and develops, Woodward added.
“One
reason to engage in basic science is to better understand the development of the
brain and mind. Here we looked at the development of social cognition, social
behavior, and the motor system, all of which are critical for human development
and are often disrupted in developmental disabilities, including autism.”
