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New analysis of infants lends further credence to the rapidly advancing theory of mirror neurons. Key to learning, mirror neurons fire in our brains when we perform physical actions but also fire similarly when we observe other people conducting those same actions. Psychologist Claes von Hofsten of Uppsala University in Sweden has shown that these cells become active before our first birthdays, earlier than scientists had anticipated.
In a 2003 experiment adults stacking blocks shifted their gaze to the site to which they were moving a block a few hundred milliseconds before the object reached the target. They did the same when watching others perform the same task. This year von Hofsten and his colleagues monitored the eyes of infants as they watched a video of a person putting little balls into a pail. Babies learn to perform this task at around nine months of age, suggesting that older infants should be able to anticipate the videotaped action but not younger infants. Sure enough, the eyes of one-year-old babies flicked ahead to the goal as they watched, but six-month-olds gazed willy-nilly.
In a control experiment the children watched animated balls moving to a basket on their own; the one-year-olds showed no anticipation in this case. Von Hofsten says the result indicates that infants evoke their own motor systems to understand other people’s actions, thanks to mirror neurons. Neuroscientist Marco Iacoboni of the University of California, Los Angeles, adds that “it is likely that the behavioral change is initiated by a qualitative change in mirror neurons.” An interesting next step, he notes, would be to see if differences in gaze can predict autism.