By the age of 14 months, infants are masters of imitation. They mimic all sorts of behaviors, including laboratory antics such as touching one’s forehead to a box that then lights up.
Babies on the brink of toddlerhood are not indiscriminate copycats, however. They sometimes opt for simpler ways to do what an adult shows them, signaling a budding capacity for evaluating the sensibility of others’ behavior, according to a study in the Feb. 14 Nature.
György Gergely of the Hungarian Academy of Sciences in Budapest and his colleagues studied 14 infants, all 14 months old, who watched a female experimenter perform the forehead-to-light-box trick under two conditions. In an initial series of trials, the woman pretended to be cold and executed the head action while her hands held a blanket around her. In a second set of trials, she performed the same head maneuver with no blanket, her hands resting next to the light box.
When the woman’s hands were occupied, only three infants reenacted her head action. When her hands were free, that number rose to 10. In both sets of trials, most of the infants who did not mimic the forehead-to-box action lit the box instead by touching it with their hands.
Infants opted for this simpler technique when they figured that the adult had a good reason–holding the blanket–for not using her hands on the box, the researchers theorize.
This finding coincides with positron emission tomography data, published in the February NeuroReport, indicating that separate brain networks orchestrate the imitation of specific actions for achieving a goal versus the accomplishment of a goal by means of one’s own choosing. As 10 men duplicated a series of actions by an experimenter arranging toy blocks, increased activity occurred uniquely in a frontal-brain area already implicated in making preparations for forthcoming actions. When the men built the same structure in their own way, however, activity increased primarily in a midbrain section involved in coordinating movements.
“Just as we distinguish between a person’s goals and his or her technique for trying to reach those goals, the brain also separates means from goals,” says study coauthor Andrew N. Meltzoff of the University of Washington in Seattle.