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
