mise à jour du 13 mars 2002
2002; 415; 14
Rational imitation in preverbal infants
Babies may opt for a simpler way to turn on a light after watching an adult do it
Gyôrgy Gergely, Harold Bekkering, Ildiko Kiràly
Institute for Psychology, Hungarian Academy of Sciences, 1132 Budapest, Hungary
Max Planck Institutefor Psychological Research, Munich, Germany
The perception-behavior expressway:automatic effects of social perception on social behavior


Here we show that if an adult demonstrates a new way to execute a task to a group of infants aged 14 months, the children will use this action to achieve the same goal only if they consider it to be the most rational alternative. Our results indicate that imitation of goal-directed action by preverbal infants is a selective, interpretative process, rather than a simple re-enactment of the means used by a demonstrator, as was previously thought.

In Meltzoff 's seminal study, a group of 14-month-old subjects watched a demonstrator illuminate a light-box by leaning forwards and touching its top with her forehead. One week later, two-thirds of them re-enacted this head action to achieve the same outcome, although none of the control group used it spontaneously. This was taken as evidence that infants separate the goal from the means, automatically imitating the means as demonstrated. Such imitative learning is thought to be specific to, humans, as primates do not imitate new strategies to achieve goals, relying instead on motor, actions already in their repertoire (emulation) If this were also the case in infants, they would be expected to touch the box with their hands, rather than imitating the unfarniliar head action. (Meltzoff, however, did not report such hand actions.)

The readiness of infants to re-enact the head action is surprising, given that 1-yearold babies can evaluate the rationality of the means in relation to the goal and the constraints of the situation. When constraints change, these infants are able to work out the most effective action that the demonstrator should use to achieve the goal (the principle of rational action). Infants would therefore be expected to re-enact an action only if it seemed te, them to be the most effective means to achieve the goal.

So why did Meltzoffs subjects re-enact the head action, when they could just have touched the box with their hands? If infants noticed that the demonstrator declined to use her hands despite the fact that they were free, they may have inferred that the head action must offer some advantage in turning on the light. They therefore used the same action themselves in the sarne situation.

To test this idea, we replicated Meltzoffs study'with one modification in one condition, the subjects could see that the demonstrator's hands were occupied while she executed the head action (pretending to be cold, she had wrapped a blanket around herself which she held onto with both hands). After witnessing the same head action when the adult's hands were free, 69% of infants re-enacted the head action, replicating Meltzoff's results'. However, after watching the adult turn on the light with her head when her hands were occupied, the number of children who imitated the head action dropped significantly te, only 2 1 % (P < 0.02). he must therefore have seemed sensible to the infants that the demonstrator should use the head action when her hands were occupied nevertheless, 79% of them chose not to imitate her because their own hands were free, presumably concluding that the head action was not the most rational.

Whether they re-enacted the head action or not, all infants who watched the adult perform, under both conditions still used the hand action. This suggests that 14-monthold infants are still subject to an automatic, emulation-like process whereby the memory of the effect (illumination by touch) activates the response that is most strongly associated with establishing contact (hand action). But the re-enactment of the head action, when inferred to be rational by the infant, indicates that imitation by 14 month-olds goes beyond emulation. We conclude that the early imitation of goal-directed actions is a selective, inferential process that involves evaluation of the rationality of the means in relation to the