Institute for Psychology,
Hungarian Academy of Sciences, Budapest, Hungary
Max Planck Institute for Psychological Research,
Munich
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 studyl 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 unfamiliar 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 to them to
be the most effective means to achieve the
goal.
So why did Meltzoff's 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
same 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; bands occupied). 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 to only 21 % (P < 0.02). If
must therefore have seemed sensible to the
infants that the demonstrator should use the
head action, wehen her hands were occupied -
nevertheless, 79% of them chose not to imitate
her because their own hands were free,
presumably conduding 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,
ernulation-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 14month-olds goes beyond emulation.
We conclude that the early imitation of
goaldirected actions is a selective, inferential
process that involves evaluation of the
rationality of the means in relation to the
constraints of the situation.
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