Individual Variations in Cognitive Development

Infancy and Childhood: Cognitive Development
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include shopping, eating at McDonald’s, going to birthday parties, and attending religious services. In other cultures they might include helping to make pottery, going
hunting, and weaving baskets (Larson & Verma, 1999). Quite early, children develop
mental representations, called scripts, for these activities (see the chapter on thought,
language, and intelligence). By the time they are three, children can describe routine
activities quite accurately. Scripts, in turn, affect children’s knowledge and understanding of cognitive tasks. For example, in cultures in which pottery making is important,
children display conservation about the mass of objects sooner than children do in
other cultures (Gardiner & Kosmitzki, 2005).
Children’s cognitive abilities are also influenced by the language of their culture.
Korean and Chinese children, for instance, show exceptional ability at adding and subtracting large numbers (Miller et al., 1995). As third-graders, they do in their heads
three-digit problems (such as 702 minus 125) that their peers in the United States labor
over or fail to solve. The difference seems traceable in part to the clear and explicit
words that Asian languages use for the numbers from eleven to nineteen. In English,
the meaning of the words eleven and twelve, for instance, is not as clear as the Asian
ten-one and ten-two. Moreover, Asians use the abacus and the metric system of measurement, both of which are structured around the number ten. Korean math textbooks
emphasize this tens structure by presenting the ones digits in red, the tens in blue, and
the hundreds in green. Above all, for children in Asian cultures, educational achievement, especially in mathematics, is encouraged at home and strongly encouraged in
school (Naito & Miura, 2001). In short, children’s cognitive development is affected in
ways large and small by the culture in which they live (Tomasello, 2000).
Individual Variations in Cognitive Development
Even within a single culture, some children are mentally advanced, whereas others lag
behind their peers. Why? As already suggested, heredity is an important factor, but
experience also plays a role. To explore how significant that role is, psychologists have
studied the cognitive development of children raised in many different environments.
Cognitive development is seriously delayed if children are raised in environments in
which they are deprived of the everyday sights, sounds, and feelings provided by conversation and loving interaction with family members, by pictures and books, and even
by television, radio, and the Internet. Children subjected to this kind of severe deprivation show significant impairment in intellectual development by the time they are
two or three years old. “Genie” was one such child. When rescued at age fourteen, she
weighed only fifty-nine pounds. The only things she could say were “stop it” and “no
BABIES AT RISK The cognitive development of infants raised in this understaffed Russian orphanage will be
permanently impaired if they are not
given far more stimulation in the orphanage or, better yet, adopted into a loving
family at a young age.
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Chapter 9
Human Development
WHEN DOES STIMULATION BECOME
OVERSTIMULATION? A child’s cogni-
tive development is enhanced by a stimulating environment, but can there be too
much stimulation? In the face of an avalanche of electronic media aimed specifically at babies and toddlers, some people
are beginning to wonder. These stimulating media include computer “lapware,”
such as this baby is enjoying, videos and
DVDs for even the tiniest infants, and, of
course, the Teletubbies. Many babies in
Western countries are immersed in electronic media for hours each day. In the
United States, more than 25 percent of
children under two have a TV set in their
rooms, and one-third of them have
videos in the “Baby Einstein” series
(Lewin, 2003). We don’t yet know how all
this well-intentioned electronic stimulation is affecting young children because
we don’t yet have enough evidence on
which to base conclusions.
more.” Investigators discovered that she had spent her life confined to a small bedroom,
harnessed to a potty chair during the day and caged in a crib at night. She had not
been permitted to hear or make many sounds. Although scientists and therapists
worked intensively with Genie in the years after her discovery, she never learned to
speak in complete sentences, and she remains in an adult care facility.
Cognitive development may also be impaired by less extreme conditions of deprivation, including the neglect, malnourishment, noise, and chaos that occur in some
homes. A study of the effects of poverty found that by the time they were five years
old, children raised in poverty scored nine points lower on IQ tests than did children
in families whose incomes were at twice the poverty level—even after the researchers
had controlled for all other family variables, such as family structure and parents’ education (Duncan, Brooks-Gunn, & Klebanov, 1994). A more recent study of more than
10,000 children found that the economic status of the family into which a child is born
is a much better predictor of the child’s later cognitive development than are physical
risk factors such as low birth weight (Jefferis, Power, & Hertzman, 2002).
In families with incomes above the poverty line, too, children’s cognitive development
is related to their surroundings and experiences. Parents can often make the difference
between a child’s getting A’s or getting C’s. To help children achieve those A’s, adults can
expose them, from the early years, to a variety of interesting materials and experiences—
though not so many that the child is overwhelmed. Children’s cognitive development is
also enhanced when parents read and talk to them, encourage and help them to explore,
and actively teach them (Gottfried, 1997)—in short, when they provide both support
and challenge for their children’s talents (Yeung, Linver, & Brooks-Gunn, 2002).
To improve the cognitive skills of children who do not get these kinds of stimulation,
developmental psychologists have provided some children with extra lessons, materials,
and educational contact with sensitive adults. In the United States, the most comprehensive effort to provide this kind of help has been through Project Head Start, a preschool
program for poor children. Many smaller, more intensive programs have also been carried
out. In a variety of such programs, children’s cognitive abilities have been enhanced (Love
et al., 2005; Ramey, Ramey, & Lanzi, 2006), and some effects can last into adulthood
(Campbell et al., 2001). Music lessons can also promote children’s cognitive development,
especially verbal memory (Ho, Cheung, & Chan, 2003; Rauscher et al., 1997; Schellenberg,
2004). Even electronic games, although they are no substitute for adult attention, can provide opportunities for school-age children to hone spatial skills that can help improve their
performance in math and science (Green & Bavelier, 2003; Greenfield et al., 1994).