Individuals seems to
develop their knowledge in a similar manner to scientists
in general: on the basis of a particular level of knowledge,
they make a transition to another level that lets them grasp
reality more accurately.
Thus, a small child does not look at the world the way an adult
does, any more than the people in the Middle Ages who believed
the world was flat saw the world in the same way that scientists
people cannot remember their births or the first few years
of their lives, you might think we were all amnesic at those
times. But that is neither true nor false. Babies do in fact
because they so effectively remember everything they learn
during those decisive years, such as how to walk and talk.
We also know that babies only a few months old show more
interest in a picture that they have never seen before than
in one that they saw yesterday—proof that they have
the latter stored somewhere in their memories.
But babies retain only scattered impressions of their experiences,
because not all of their brain circuits are complete at birth.
of the axons, in particular, is still incomplete,
and they do not yet interconnect the various parts of the brain
effectively. Because a coherent memory requires simultaneous
contributions from very diverse regions of the brain, babies
memories’ are therefore still fragmentary.
PIAGET’S MODEL OF COGNITIVE DEVELOPMENT
From birth until death,
human beings continue to change as they go through the various
stages of their lives—infancy (the first month of life),
babyhood (until about age 2), early childhood (until age 5
to 7), childhood (until age 11 or 12), pre-adolescence (until
age 13 or 14), adolescence (until age 17 to 20), adulthood
(until age 60 to 70), and then old age.
Intuitively, we perceive each of these somewhat arbitrary divisions as a major
stage in our lives, but some researchers have tried to determine whether they
do in fact correspond to actual stages in the development of our intellectual
Swiss psychologist Jean
Piaget (1896-1980) was one of the first people
to examine this question systematically. His pioneering
role in developmental psychology has often been compared
to Darwin’s pioneering role in our understanding
of the development of species, which is no small compliment.
But whereas Darwin had to sail around the world for five
years to accumulate his data, Piaget began gathering his
in his own home, by studying his own children! He thus
became the first to show that children are not less intelligent
than adults, but simply reason in a different manner.
How do these early modes of thought evolve as the child grows
to adulthood? That is the question that occupied Piaget for a large
part of his life. And the basic answer he provided is that thought
develops in stages. Whenever a developing individual reaches a
new stage, it results in the rebuilding of the entire edifice of
knowledge that he or she had acquired up to that point.
It is not just the data
that Piaget gathered that made him famous, but also his “clinical
method”. In this approach, which Piaget pioneered,
the experimenter plays a father-like role in semi-structured
conversations with the child.
Still used today in various forms, this approach focuses
not so much on the child’s answers as on the reasoning
that underlies them. When children gave incorrect answers,
Piaget found that they always provided far more insight
into the workings of the children’s mind than correct
answers would have.
Here is an example of a typical dialogue, between Piaget
and a 5-year-old girl named Julia.
Piaget: What makes the wind?
Julia: The trees.
P: How do you know?
J: I saw them moving their branches.
P: How does that make the wind?
J: Like this (waving her hands in front of her face). Only
the branches are bigger. And there are lots of trees.
P: What makes the wind on the ocean?
J: It blows there from the land. No. It’s the waves…
From this discussion, Piaget concluded that though this
little girl’s beliefs about the wind were false,
they were completely consistent within the framework of
her young thought system.
In one type of conservation-of-number
experiment, the experimenter shows a child
two rows of marbles that are equal in number but one
of which is more widely spaced, then asks the child
whether the number of marbles in the two rows is the
same. Children as young as 3 can give the correct answer.
In Piaget’s version of this experiment, however,
he asked the same question twice: first with the two
rows spaced the same, and then spaced differently.
Only older children could tell that the number of marbles
was still the same. The reason may have been that because
the children were asked the same question twice, the
younger ones felt that a different, negative, answer
must have been expected the second time.
BEYOND PIAGET’S MODEL
historical contribution to
developmental psychology is considerable. His greatest achievement
may well have been his having introduced the empirical study of
the psychological development of children, a practice that was
almost completely new in the 1940s.
Most developmental psychologists today no longer accept
all aspects of Piaget’s
theories as he proposed them. As often happens in science,
his pioneering studies have now been subjected to numerous
criticisms that have highlighted their limitations.
Many of these criticisms concern his
research methods. Piaget studied his own children and the
children of his colleagues in Geneva in order to deduce general
principles about the intellectual development of all children.
Not only was his sample very small, but it was composed solely
of European children from families of high socio-economic
status. That is why many scholars have questioned the representativity
and even the reliability of his data—not only because
of his limited number of subjects, but also for having neglected
Other critics say that Piaget’s experiments were designed
more to trap children than to try to see just how far their reasoning
could take them if they were given enough information. Indeed,
many, more recent studies have shown that young children actually
have greater cognitive abilities, at least under certain conditions,
than were reported in Piaget’s studies (see sidebar).
Some doubts have also been raised about how children understood the words that
Piaget used in the questions that he asked them. For example, does “more” or “the
same thing” have exactly the same meaning to a child as it does to you?
Lastly, some critics argue that Piaget greatly underestimated the value
of social learning, the kind that comes from parents or, later in life, from
The idea that we can
have innate behaviours that are already adapted to the
world into which we are born may seem surprising until
we recall the long
process of evolution that resulted in the brains we have
now. Anyone who has watched animals being born
and is the least bit observant can testify to the evidence
of numerous instinctive behaviours.
Such behaviours are “pre-wired” into the nervous
system long before the animals have had any memorable experiences.
These behaviours and their neurological substrate have probably
evolved to improve the newborns’ chances of surviving
in a world fraught with predictable perils and difficulties.
The innate behaviours of birds provide an especially eloquent
example of this phenomenon. Just consider, for instance,
the complex sequence of movements that chicks must execute
in order to emerge from their eggs.
In fact, during certain early periods of life, the neural pathways are highly
sensitive to environmental influences, and a veritable remodelling of the brain
is possible. These intervals of time are known as critical periods.
One of the first examples of a critical period to be studied was the period when
young birds are susceptible to imprinting, a form of learning
first described by Konrad Lorenz, one of the
fathers of the science of ethology.
In the mid-1930s, Lorenz observed that
just after birth, greylag goslings quickly become attached
to the first large object that moves in front of them. Most
of the time, this is their mother. But if their mother is not
there, the goslings will form this attachment with any moving
object of sufficient size and follow it around as if it were
their mother. In Lorenz’s experiments, the objects in
question were his own wading boots!
This imprint is acquired very rapidly and, once acquired, generally
never goes away. (Indeed, Lorenz chose the term “imprint” to
suggest the permanence of the trace thus left in the young animals’ brains.)
An imprint can form only during a limited period of time (in the
goslings’ case, no more than two days after the eggs have
hatched), which is why the term “critical period ” is
used to describe this decisive phase in social attachment.
Though certain periods
in our early lives are critical for the smooth development
of our perceptual and social skills, experiences later in
life still influence our brains through our learning