What have you observed about the cognitive capabilities of a newborn child

 Related to these biological changes are the enormous gains that infants make in being able to move their bodies. At 3 months of age, infants are just beginning to be able to roll over, and their parents can be confident that they will remain more or less wherever they are put down.That soon changes.At about 7 to 8 months, infants begin to crawl; at about 1 year, they begin to walk in the toddler’s drunken, uncoordinated fashion demonstrated by Jake; and by the time they are 2, they can run, take a few steps backward, and walk up stairs (with a helping hand). During this period, infants also become much more adept at manipulating objects. At 1 year of age, babies prod, bang, squeeze, push, and pull almost anything they can get their hands on, including the neighbor’s dog, and they often put objects into their mouths to learn about them; at 2 years of age, they possess enough control to feed themselves with a spoon, to toss a large ball, to open cabinets, drawers, and boxes, and to pet, rather than poke at or thump, the dog.As infants’ mobility, motor control, and curiosity about the world in- crease, their parents must constantly be on the watch to keep them out of harm’s way.

Important changes also occur in infants’ cognitive abilities. Older babies learn more rapidly and remember what they have learned for longer periods of time. By the end of infancy, babies can remember actions they have observed others per- form, in person or on television, and can imitate them days later in play. They can follow simple directions, and they laugh when someone does something silly like wear a cooking pot for a hat. They also begin to use symbols, turning a banana into a telephone or a wooden block into a race car. Of special significance is their emerging mastery of that uniquely human symbol system, language.

These changes in biological makeup, motor behavior, and cognitive capacities interact throughout infancy. We will focus on them in this chapter, and in the next, we will turn to the substantial social and emotional developments that they help make possible. The physical differences between a 3-month-old and a 2-year-old are so striking that it’s hard to believe that so much could have changed in a scant 21 months (Figure 5.1). There are changes in body size and proportions and in the muscles and bones, as well as in the brain. These changes are connected both with each other and with the development of the new behavioral capacities babies display. For ex- ample, their greater weight requires larger and stronger bones to support them and stronger muscles to enable movement. Their developing cognitive capacities make them want to explore new aspects of the world, but to explore the world they must coordinate their constantly changing size and strength in new ways.

Size and Shape

During their 1st year, most healthy babies triple in weight and grow approximately 10 inches; in the United States, the typical 1-year-old weighs 20 to 22 pounds (9 to 10 kg) and stands 28 to 30 inches (71 to 76 cm) tall. During the second year of life, children’s bodies continue to grow rapidly, though at a much slower rate (Bogin, 2001); in the United States, children on average gain 5 pounds (2.2 kg) and grow 4 inches (10.6 cm), to about 27 pounds and about 34 inches (12.2 kg and 86.3 cm). (This tapering off of the growth rate, apparent in Figure 5.2, continues until adolescence, when there is a noticeable growth spurt.) Also by 2 years of age, most children will have all their baby teeth.

Increases in babies’ height and weight are accompanied by changes in their body proportions (see Figure 5.3). At birth, the baby’s head is 70 percent of its adult size and accounts for about 25 percent of the baby’s total length. By 1 year of age, the head will account for 20 percent of body length, and by adulthood, 12 percent.Infants’ legs at birth are not much longer than their heads; by adulthood the legs account for about half of a person’s total height. By 12 months, the changes in body proportions have led to a lower center of gravity, making it easier for the child to balance on two legs and begin to walk (Thelen, 2002). As their bodies stretch out, most babies will lose the potbellied look so characteristic of early infancy; they begin to look more like children than infants.

It should be noted that norms for children’s growth, such as those depicted in Figure 5.2, are derived by averaging large samples of children and that indi- vidual children normally grow at widely varying rates (Tanner, 1998). Many fac- tors contribute to these variations, including not only genetic factors but also, for example, diet, socioeconomic status, and maternal health (Ruel & Menon, 2002; Pelletier & Frongillo, 2003). Sometimes these factors can lead to significantly slower growth rates, known as infant growth restriction. Infant growth restriction is associated with a number of serious problems, including SIDS, developmental delay, infections, and poor psychological health. One study of several thousand babies born in a rural area of Malawi found that infant growth was significantly restricted if mothers contracted malaria during their pregnancies, or were illiter- ate and presumably less educated about infant and maternal health (Figure 5.4; Kalanda, van Buuren,Verhoeff, & Brabin, 2005).The researchers note that infant growth restriction poses a special challenge in less developed countries where the postweaning diet is low in protein, and they suggest that controlling malaria during pregnancy and educating girls and young women may help curb the in- cidence of this serious threat to children’s health and development.

the Musculoskeletal System

As babies grow, the bones and muscles needed to support their increasing bulk and mobility undergo corresponding growth. Most of a newborn’s bones are relatively soft, and they harden (ossify) only gradually as minerals are deposited in them in the months after birth. The bones in the hand and wrist are among the first to ossify. They harden by the end of the 1st year, making it easier for a baby to grasp objects, pick them up, and play with them. At the same time, infants’ muscles increase in length and thickness, a process that continues throughout childhood and into late adolescence. In infancy, increases in muscle mass are closely associated with the de- velopment of the baby’s ability to crawl, stand alone, and walk.

Although boys are generally larger than girls, as Figure 5.2 clearly indicates, re- search supports the common wisdom that girls mature faster than boys. In fact, sex differences in growth rates are apparent even before birth: Halfway through the prenatal period, the skeletal development of female fetuses is some 3 weeks more advanced than that of male fetuses. At birth, the female’s skeleton is from 4 to 6 weeks more mature than the male’s, and by puberty it is 2 years more advanced. (Girls are more advanced in the development of other organ systems as well. They get their permanent teeth, go through puberty, and reach their full body size earlier than boys do [Bogin, 1999].)

The physical changes of infancy described above open wholly new ways of ex- ploring and learning about the environment. Equally significant in making these possible are the changes taking place in the brain.The development of the baby’s brain is as fascinating as it is important. As dis- cussed in Chapter 4 (pp. 128–129), the brain has evolved in such a way that it de- velops through both experience-expectant and experience-dependent processes. In experience-expectant processes, the brain expects that the world will present par- ticular, species-universal experiences—patterns of light and dark, various kinds of tastes and odors, language, and the like—and develops in response to those experi- ences. In experience-dependent processes, development occurs in response to specific experiences—hence the brain’s amazing capacity to be changed by the unique experiences of each individual child.

In their efforts to understand infant brain development, researchers have fo- cused on answering two interconnected questions. One concerns the relationship between brain and behavior: What is the relationship between developments in certain parts of the brain and the onset of new skills or abilities? The other key question concerns the relationship between brain and experience: To what extent does experience or the lack thereof (that is, deprivation) enhance or impede brain development and function?

Brain and Behavior

As we discussed in Chapter 4, the brain undergoes substantial development through- out infancy, although different parts grow at different times and rates. The cerebral cortex, as you may recall, is very immature at birth. Because the cortex is associated with such complex functions as voluntary (as opposed to reflexive) behavior, ab- stract thought, problem solving, and language, its development has been of special interest to researchers eager to understand brain–behavior relationships.

The prefrontal area of the cortex, located behind the forehead, plays a par- ticularly important role in the development of voluntary behavior. It begins to function in a new way sometime between 7 and 9 months of age. With this change in functioning comes an increase in infants’ ability to regulate themselves (Posner et al., 2007). Infants can stop themselves from grabbing the first attractive thing they see; they can cuddle their teddy bear to keep from being upset when they are put down for a nap. With the emerging ability to inhibit action, they can also better control what they attend to. In effect, they begin to be able to stop and think (Diamond, 2000; Stevens, Quittner, Zuckerman, & Moore, 2002).

Another important development, revealed by brain-imaging techniques, involves the language-related areas of the cortex. These areas, in the frontal and temporal lobes, undergo significant myelination shortly before a characteristic spurt in tod- dlers’ vocabulary (myelin, remember, is the fatty substance that covers axons, speed- ing the brain’s communications) (Pujol et al., 2006; see Chapter 7, p. 240).

At least as important as the growth of different brain areas is that the differ- ent areas increasingly function together (Bruer & Greenough, 2001; Fox, Levitt, & Nelson, 2010). Once again, myelination plays an important role. For exam- ple, myelination of the neurons that link the prefrontal cortex and frontal lobes to the brain stem, where emotional responses are partially generated, creates a new potential for interaction between thinking and emotion. In general, the greater synchrony among brain areas appears vital to the emergence of func- tions that define late infancy, including more systematic problem solving, the voluntary control of behavior, and the acquisition of language (Richmond & Nelson, 2007).

As the physical body, and the ability to control it, continue to mature across the first 2 years after birth, so too does the mind. As we shall see in the following sec- tions, developmentalists are engaged in a great debate about how thinking pro- gresses during the first 2 years.

For some developmentalists, such as Piaget, the mind undergoes a radical, discon- tinuous shift at the end of infancy (Müller,2009).According to Piaget’s stage theory, young infants are limited to sensorimotor intelligence; that is, they understand the world only through their own actions and perceptions.They, therefore, cannot think about people and objects that are not immediately present to be seen, heard, or felt, and acted upon. All this changes fundamentally at age 18 or so months of age, when in- fants become capable of representational thinking, forming mental pictures or images of the world.The ability to form such mental images, and to reason about them, is a significant turning point in cognitive development. Knowledge is no longer tied to the immediate here and now. Instead, infants can hold in mind past experiences, compare and contrast them with each other and with present circumstances, and use them to anticipate the future and guide their actions. Developmentalists who take this view claim that the emergence of the ability to represent the world mentally re- sults in a mind that is truly conceptual, rather than simply “sensorimotor.”

On the other side of the debate are developmentalists who maintain that mental development is more continuous than Piaget supposed—that the ability to represent and understand the world conceptually is present very early in development, if not from birth. According to this view, conceptual understanding does not emerge out of sensorimotor knowledge, as Piaget claimed. Instead, young babies are believed to possess at least a rudimentary conceptual system.This system is thought to develop separate from, although in close association with, the sensorimotor system (Mandler, 2007; Moore & Meltzoff, 2004). As you will see below, there is much at stake in the debate about the nature and development of the human mind.