Individual Variations in Cognitive Development
Infancy and Childhood: Cognitive Development 359 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. 360 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).