When an adult watches another person move an object from one place to another, his or her eyes go to the target before the other person’s hand completes the movement. Claes von Hofsten and colleagues from Uppsala University in Sweden report in the June 18 advance online publication of Nature Neuroscience that infants as young as 12 months old also anticipate another’s action, while 6-month-old infants simply follow the movement with their eyes as it progresses.
Our ability to foresee someone else’s action before it is completed is controlled by a group of cells in the brain called mirror neurons. These neurons fire when we perform an action or when we watch someone else perform one, suggesting that “we understand the actions of other people by sort of simulating them in our own motor systems,” von Hofsten says. (For another perspective on mirror neurons, please see “Terms of Empathy,” May-June 2006 BrainWork, page 3.)
To find out how early this ability develops in children, von Hofsten’s group had a model move an object from a tabletop to a bucket. When adults or 12-month-old infants watched the movement, their eyes looked to the bucket before the model’s hand arrived. The 6-month-old babies followed the model’s hand but they did not anticipate the target.
von Hofsten thinks mirror neurons provide an important shortcut to learning new movements because we simulate another person’s movement in our own motor cortex, making it easier for us to perform the action ourselves. The fact that infants can already do this at 1 year hints that mirror neurons may help children learn social behaviors and patterns.