There is a pendulum that swings back and forth in the study
of child development. The work of Piaget
generally assumed that infants have very little knowledge and react to the
sights and sounds of the world as their movement abilities improve. Gradually, children learn more complex
concepts, and in the end adults have an impressive capacity to reason.
Starting in the 1980s, there was a challenge to this
view. Studies of young infants suggested
that they have a much greater understanding of the world than Piaget
proposed. For example, studies by Renee
Baillargeon and her colleagues suggested that infants as young as 5-months-old
understood that objects that were hidden by a screen were still there. These studies led to a flurry of research
exploring infants’ abilities.
More recently, the pendulum has started to swing back. The difficulty with doing studies with
infants is that you can’t ask them specific questions, because their language
abilities are just developing. Instead,
you have to find indirect ways to explore what they are thinking. Then, you
have to interpret what infants’ must have been thinking in order to have acted
that way. It is easy to fall into the
trap of rich interpretation, which you (as an adult) think about what would
have made you act that way. That can
lead you to overestimate what infants know.
This pendulum can be seen in research on imitation in
infants.
Anyone who has been around an infant for any length of time
can see their imitation skills in action.
I have a great picture of my brother holding one of my kids who was
about 5-months old. Both of them are
sticking their tongue out at the camera.
This picture was the result of an hour in which my brother stuck his
tongue out, and then my son stuck his tongue out in response.
How does this imitation happen?
One theory, which falls in the “infants don’t know that
much” camp, assumes that imitation is based mostly on the way that infants
represent movements. This theory
suggests that the way that people understand the movements of other people is
based in part on using the parts of the brain that are associated with making
movements. In essence, when we watch
someone else performing an action, our own movement system is engaged in
simulating what the other person is doing.
Infants imitate, because this activity of the movement system prepares
them to make the same movements they just observed.
A second theory, which is more in the “infants know a lot”
camp, assumes that infants are trying to figure out what the person they are
imitating was trying to do. This view
suggests that infants are constantly reasoning about why people do what they
do, and then they imitate what someone intended rather than what they actually
did.
The view that infants
are imitating the goals of someone else got support from a 2002 study in the
journal Nature by Gyorgy Gergely,
Harold Bekkering, and Ildiko Kiraly.
They had an adult sit in front of a box with a light on the top. The light could be turned on by pressing on
it. The adult sat across from a
14-month-old infant (who was sitting on a parent’s lap). In one condition, the adult had her hands on
the table, and then bent over and pressed the light with her forehead to turn
it on. In the other condition, the adult
was wrapped in a blanket so that her hands were not available to use, and she
bent over and pressed the light with her forehead. After watching the experimenter, the infant
was allowed to play with the lamp.
The idea here was that
if infants just imitate actions, then they should press the light with their
forehead in both conditions of the study.
However, if infants are reasoning about what the adult is trying to do,
then when the adult’s hands were under the blanket, infants should realize that
the adult just wanted to turn the light on and used her head because her hands
were not free to use. Consistent with
the idea that children were reasoning about goals, the infants were much more
likely to touch their head to the light when the adult had her hands on the
table (so that she clearly chose to use her head) than when the adult had her
hands under the blanket.
A study in the July 2011
issue of the journal Child Development
by Markus Paulus, Sabine Hunnius, Marlies Vissers, and Harold Bekkering suggests
that children might not have been reasoning about the goal of the adult after
all.
These researchers note
that for infants to use their head to turn on the lamp, they have to put their
hands on the table to steady themselves, because their stomach muscles are not
strong enough to hold them up when leaning over without support. That action is quite similar to the one the
experimenter makes when putting her hands visibly on the table in the original
study.
To see whether children
are focusing on actions they are able to perform, these researchers added three
more conditions to the
study I just described (in addition to the conditions in which the adult had
her hands on the table and the one where her hands were trapped under a
blanket).
In one condition, the
adult had her hands under a blanket, but the blanket had an obvious button that
was holding it closed so that the adult could easily use her hands if she
wanted to. If the infants are just
reasoning about the adults’ goal, then they should use their heads to press the
button, because the adult clearly chose to use her head. However, if it was important that the adult
had her hands on the table, then the infants would not use their head in this
case. In fact, infants rarely used their
head to turn on the light when the adult had her hands under the blanket with
the button holding it closed.
In another condition,
the adult had her hands in the air and then bent over and pressed the button
with her head. Again, children reasoning
about the adult’s goals should use their heads, because the adult clearly chose
to use her head rather than her hands.
However, children can’t lean over with their hands in the air, so if
they just wanted to imitate an action, they wouldn’t use their head in this case
(because they would fall over). Once
again, infants rarely used their heads.
In the third condition,
the adult started the task by playing with two foam balls. Then, she held one ball in each hand and put
her hands on the table while holding the balls and bent over and touched the
light with her head. Children reasoning
about goals should not use their heads in this case, because they should see
that the adult’s hands were occupied holding the balls and so she used her
forehead out of convenience. Children
who are imitating an action they can perform should use their heads, though,
because the adult had her hands on the table, and if the infants put their hand
on the table, they could support themselves as they bent over. In this condition, the infants often pressed
he light with their head.
Putting all of this
together, then, it looks like the pendulum has swung back toward a focus on the
influence of movement ability on imitation.
Early on, infants are trying to imitate actions they can perform themselves. These findings are quite consistent with a
lot of research about the way that adults think about actions. Generally speaking, even adults understand actions
by thinking about how we could perform them ourselves. It is just a short step from that
understanding to doing the same thing. In that way, infants may not be that different
from adults. Perhaps we’re guilty of
rich interpretation of adult performance as well.
