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The Development of Knowledge Piagets Theory

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The Development of Knowledge Piagets Theory
349
Infancy and Childhood: Cognitive Development
FIGURE 9 .2
Reflexes in the Newborn
When a finger is pressed into a newborn’s
palm, the grasping reflex causes the infant
to hold on tightly enough to suspend its
entire weight. And when a newborn is held
upright over a flat surface, the stepping
reflex leads to walking movements.
Voluntary control permits the development of motor skills, allowing the infant to
roll over, sit up, crawl, stand, and walk. Until a few years ago, most developmental psychologists accepted Gesell’s view that, except under extreme environmental conditions,
these motor abilities occur spontaneously as the central nervous system and muscles
mature. Research demonstrates, however, that maturation does not tell the whole story,
even in normal environments (Thelen, 1995).
Consider the fact that many babies today aren’t learning to crawl on time—or at all.
Why? One reason has to do with the “Back to Sleep” campaign begun a decade ago in
an effort to prevent sudden infant death syndrome (see the chapter on consciousness).
This public health campaign urges parents to put babies to sleep on their backs rather
than face down. The campaign has been successful, but researchers have discovered that
many babies who were never placed on their tummies went directly from sitting to toddling, skipping the crawling stage but reaching all other motor milestones on schedule
(Kolata & Markel, 2001).
Observation of infants who do learn to crawl has shown that it does not happen
suddenly. It takes the development of enough muscle strength to support the
abdomen—and some active experimentation—to get the job done. Six infants in one
study tried various crawling techniques—moving backward, moving one limb at a time,
using the arms only, and so on (Freedland & Bertenthal, 1994). After a week or two of
trial and error, all six infants arrived at the same method: moving the right arm and
left leg together, then the left arm and right leg. This pattern turned out to be the most
efficient way of getting around quickly without tipping over. Such observations suggest
that as maturation increases infants’ strength, they try out various motor patterns and
select the ones that work best (Nelson, 1999).
In other words, motor development results from a combination of maturation and
experience. It is not the result of an entirely automatic sequence that is genetically
etched in the brain. Yet again, we see that nature and nurture influence each other. The
brain controls developing behavior, but its own development is affected by experience,
including efforts at building motor skills.
Infancy and Childhood: Cognitive
Development
䉴 How do babies think?
In less than ten years, a tiny infant becomes a person who can read a book, write a
poem, and argue logically for access to the family’s new computer. What leads to the
dramatic shifts in thinking, knowing, and remembering that occur between early
infancy and later childhood? Researchers studying cognitive development try to answer
this question.
The Development of Knowledge: Piaget’s Theory
Foremost among these researchers was Jean Piaget, who dedicated his life to a search
for the origins of intelligence and the factors that lead to changes in knowledge over
the life span. Piaget was the first to chart the journey from the simple reflexes of the
newborn to the complex understandings of the adolescent. Although his theory turned
out to be incomplete, and in some respects incorrect, his ideas about cognitive development are still guiding research (Fischer & Hencke, 1996).
Intensive observations of infants (including his own) and extensive interviews with
children led Piaget to propose that cognitive development proceeds in a series of distinct stages, or periods. He believed that all children’s thinking goes through the same
stages, in the same order, without skipping. (Table 9.1 outlines these stages.) According to Piaget, the thinking of infants is different from the thinking of children, which
in turn is different from that of adolescents. He said that children are not just miniature
350
TA B L E
Chapter 9
9.1
Piaget’s Periods of Cognitive
Development
According to Piaget, a predictable set of
features characterizes each period of children’s cognitive development. The ages associated with the stages are approximate;
Piaget realized that some children move
through the stages slightly faster or slower
than others.
Period
Activities and Achievements
Sensorimotor
Infants discover aspects of the world through their
sensory impressions, motor activities, and coordination
of the two.
They learn to differentiate themselves from the external
world. They learn that objects exist even when they are
not visible and that they are independent of the infants’
own actions. Infants gain some appreciation of cause
and effect.
Birth–2 years
Preoperational
2–4 years
4–7 years
Concrete
operational
7–11 years
Formal operational
Over 11 years
schemas Mental representations of
what we know and expect about the
world.
assimilation The process of taking in
new information about objects by using
existing schemas on objects that fit
those schemas.
accommodation The process of modifying schemas as an infant tries out familiar schemas on objects that do not
fit them.
sensorimotor period According to
Piaget, the first stage of cognitive development, when the infant’s mental
activity is confined to sensory perception and motor skills.
object permanence The knowledge
that an object exists even when it is not
in view.
Human Development
Children cannot yet manipulate and transform information in logical ways, but they now can think in images
and symbols.
They become able to represent something with something else, acquire language, and play games of pretend.
Intelligence at this stage is said to be intuitive, because
children cannot make general, logical statements.
Children can understand logical principles that apply to
concrete external objects.
They can appreciate that certain properties of an object
remain the same, despite changes in appearance, and
they can sort objects into categories. They can appreciate
the perspective of another viewer. They can think about
two concepts, such as longer and wider, at the same time.
Only adolescents and adults can think logically about
abstractions, can speculate, and can consider what might
or what ought to be.
They can work in probabilities and possibilities. They can
imagine other worlds, especially ideal ones. They can
reason about purely verbal or logical statements. They
can relate any element or statement to any other,
manipulate variables in a scientific experiment, and deal
with proportions and analogies. They can reflect on their
own activity of thinking.
adults and that they are not dumber than adults; they just think in completely different ways at different stages of development. In other words, entering each stage involves
a qualitative change from whatever preceded it, much as a caterpillar is transformed
into a butterfly.
To explain how infants and children move to
ever higher stages of understanding and knowledge, Piaget introduced the concept of
schemas as the basic units of knowledge, the building blocks of intellectual development. As noted in other chapters, schemas are the mental images or generalizations
that form as people experience the world. Schemas, in other words, organize past experiences and provide a framework for understanding future experiences.
At first, infants form simple schemas. For example, a sucking schema combines their
experiences of sucking into images of what objects can be sucked on (bottles, fingers,
pacifiers) and what kinds of sucking can be done (soft and slow, speedy and vigorous).
Later, children form more complex schemas, such as a schema for tying a knot or making a bed. Still later, adolescents form schemas about what it is to be in love.
Two related processes guide this development: assimilation and accommodation. In
assimilation, infants and children take in information about new objects by trying out
Building Blocks of Development
Infancy and Childhood: Cognitive Development
351
existing schemas and finding schemas that the new objects will fit. They assimilate the
new objects into their existing schemas. So when an infant is given a squeaker toy, he
will suck on it, thus assimilating it into the sucking schema he has developed with his
bottle and pacifier. In the same way, a toddler who sees a butterfly for the first time
may assimilate it into her “birdie” schema, because, like a bird, it’s colorful and it flies.
Now suppose an older toddler encounters a large dog. How she assimilates this new
experience depends on her existing schema of dogs. If she has had positive experiences
with the family dog, she will have a positive schema, and, expecting the dog to behave
like her pet, she will greet it happily. In other words, past experiences affect what and
how children think about new ones.
Sometimes, like Cinderella’s stepsisters squeezing their oversized feet into the glass slipper, people distort information about a new object to make it fit an existing schema.
When squeezing won’t work, though, people are forced to change, or accommodate,
their schemas to the new objects. In accommodation, the person tries out familiar
schemas on a new object, finds that the schemas cannot be made to fit the object, and
changes the schemas so that they will fit (see Figure 9.3). So when the infant discovers
that the squeaker toy is more fun when it makes a noise, he accommodates his sucking schema and starts munching on the squeaker instead. When the toddler realizes
that butterflies are not birds because they don’t have beaks and feathers, she accommodates her “birdie” schema to include two kinds of “flying animals”—birds and butterflies. And if the child with the positive “doggie” schema meets a snarling stray, she
discovers that her original schema does not extend to all dogs and refines it to distinguish between friendly dogs and aggressive ones.
Sensorimotor Development Piaget (1952) called the first stage of cognitive
development the sensorimotor period, a time when mental activity is confined to
FIGURE
9.3
Accommodation
Because the bars of the playpen are in the
way, this child discovers that her schema
for grasping and pulling objects toward her
will not work. So she adjusts, or accommodates, her schema to achieve her goal.
schemas about sensory functions, such as seeing and hearing, and to schemas about
motor skills, such as grasping and sucking. Piaget believed that during the sensorimotor stage, infants can form schemas only of objects and actions that are present—
things they can see, hear, or touch. They cannot think about absent objects, he said,
because they cannot act on them. For infants, then, thinking is doing. They do not
lie in the crib thinking about their mother or their teddy bear, because they are not
yet able to form schemas that are mental representations of objects and actions that
are not present.
The sensorimotor period ends when infants do become able to form such mental
representations. At that point, they can think about objects or actions when the
objects are not visible or the actions are not occurring. This milestone, according to
Piaget, frees the child from the here-and-now of the sensory environment. It allows
for the development of thought. One sign of this milestone is the child’s ability to
find a hidden object. This behavior reflects the infant’s knowledge that an object
exists even if it cannot be seen, touched, or sucked. Piaget called this knowledge
object permanence.
Piaget believed that before infants acquire knowledge of object permanence, they do
not search for objects that are placed out of sight. For infants, out of sight is literally
out of mind. He said that evidence of object permanence begins to appear when infants
are four to eight months old. At this age, for the first time, they can recognize a familiar object even if part of it is hidden: They know it’s their bottle even if they can see
only the nipple peeking out from under the blanket. Infants now have some primitive
mental representations of objects. If an object is completely hidden, however, they will
not search for it.
Several months later, infants will search briefly for a hidden object, but their search
is random and ineffective. Not until they are about eighteen to twenty-four months
old, said Piaget, do infants appear able to picture and follow events in their minds. They
look for the object in places other than where they saw it last, sometimes in entirely
new places. According to Piaget, their concept of object permanence is now fully developed. They have a mental representation of the object that is completely separate from
their immediate perception of it.
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