Cognitive Development Through Adolescence PDF

C H A P T E R 14 Cognitive Development Through Adolescence Piagetian Theory A little more than 13 years ago, an infant General Principles son came into my life. Despite my delig...

C H A P T E R 14 Cognitive Development Through Adolescence Piagetian Theory A little more than 13 years ago, an infant General Principles son came into my life. Despite my delight Stages of Development in this arrival, I have to admit that his Reactions to Piaget’s Theory limited behavioral and communicative repertoire made the very early months Non-Piagetian Approaches to Cognitive sometimes frustrating and stressful. His Development frequent crying often gave no clue as to Perceptual Development in Infancy the source of his problem, and it was hard Toddlers’ Acquisition of Syntax to know if he was happy, sad, mad, or glad Preschoolers’ Use of Memorial (to paraphrase Dr. Seuss) to be in the Strategies world. Conceptual Development in Early Sixty-odd months later, I was parenting Childhood a son who could print his name, tell unsus- The Development of Reasoning pecting strangers long tales of his life (real Abilities in Middle and Late and pretend), invent pretend schools (at Childhood which his imaginary teacher was Cinderella and his imaginary coach scheduled six bas- Some Post-Piagetian Answers to the ketball games a day), argue with great so- Question “What Develops?” phistication over bedtime and mealtime Neurological Maturation rules, and remember details of trips and Working-Memory Capacity and conversations that had occurred months Processing Speed earlier. Attention and Perceptual Encoding As I write this edition, I travel this jour- The Knowledge Base and Knowledge ney again with my almost 5-year-old Structures daughter. It’s amazing to watch her use her Strategies abilities and confront challenges. These Metacognition personal experiences, combined with my 498  Chapter 14 Cognitive Development Through Adolescence 499 professional interest in cognitive abilities, have led me to wonder about the origins of those abilities. So far in this book, the capacities, skills, and strate- gies used in cognitive tasks have all been described in terms of a person who has presumably mastered or acquired most, or even all, of the skills considered necessary for a fully functioning cognitive being. It can be argued, however, that our understanding of adult cognition is fundamentally incomplete unless we understand its development. The reasons that adults use their memory, reach one conclusion rather than another, or perceive something in a certain way may have a great deal to do with their previous experience with cognitive tasks as well as with their current ability to understand the demands of the task in front of them. In this chapter, we will pause to consider how cognitive capacities, skills, and strategies come to be—when and how they are acquired or mastered and what sorts of influences affect their growth. We will examine how infants and children at different points in their development cope with different cognitive tasks. Our review of cognitive development will necessarily be quite selective. There simply isn’t room in one chapter to consider the development of perfor- mance on all the cognitive tasks that we have previously discussed. Instead, we will first look at broad theoretical approaches to cognitive development, con- sidering the general question “How do cognitive abilities change and grow as an infant matures through adolescence?” To do this, we will focus on two major kinds of theoretical approaches: stage theories, such as that developed by Piaget, and nonstage theories, such as information-processing models. Stage theories of cognitive development are so named because they describe development as consisting of a series of qualitatively different periods, called stages. Each stage consists of a different way of making sense of the world. Stage theories view children as fundamentally and qualitatively different from adults in one or more respects by virtue of their being in different developmental stages. Stage theories assume that children go through stages in a fixed or stable order, never skipping stages or going backward. Presumably, the cognitive abilities and capacities gained in one stage prepare the child to acquire the abilities and capacities of the next stage. In this sense, stages build on one another. Most stage theorists also claim universality for their stages, seeing them as applicable to children from a wide variety of cultures and environments. Nonstage theories of cognitive development do not see qualitative changes at different developmental periods. Instead, these theories view development as the gradual acquisition of one or more things—for example, mental associa- tions, memory capacity, perceptual discrimination, attentional focus, knowledge, or strategies. Generally speaking, nonstage theories view children as quantita- tively but not qualitatively different from adults. 500 Part V Individual and Situational Differences in Cognition After reviewing these two theoretical approaches in greater detail, we will examine cognitive development on selective specific cognitive tasks. In doing so, we will review several proposals for what children acquire and master in the course of their development. We will see that there currently are a number of distinct, although not mutually exclusive, answers to the question “What is it that develops?” (Siegler, 1978). Developmental theories, according to Patricia Miller (1993) “have saved developmental psychology from drowning in a sea of data on children” (p. 2). Like other theories, developmental theories are organized ways of explaining phenomena. They include assumptions and predictions that can be translated into testable hypotheses. In particular, developmental theories try to explain how and why certain changes occur in children’s behavior and performance at different periods. Further, developmental theories focus mainly on long- lasting changes. Miller described three specific goals of developmental theo- ries: “(1) to describe changes within one or several areas of behavior, (2) to describe changes in the relationships among several areas of behavior, and (3) to explain the course of development that has been described” (p. 5). There are hundreds of developmental theories in psychology. Most have a narrow focus, describing only one aspect of development (such as memory or perception), and many focus on only one developmental period (such as infancy or adolescence). Here, we will first consider one very broad develop- mental approach that set out to describe and explain many aspects of cogni- tive development over a broad time span. This approach, Piagetian theory, is arguably the single most important theory in the field of cognitive develop- ment. Next we will consider alternatives to Piagetian theory. There is not one opposing theory here but rather a collection of proposals from different re- searchers. Each of these usually focuses on a more limited aspect of cognitive development. PIAGETIAN THEORY Jean Piaget (1896–1980) was fascinated by the question of how intelligence and cognitive functions come to be. He quickly rejected the idea that intelli- gence consists of the passive acquisition, storage, and organization of knowl- edge from the environment. Nor did he accept the view that intelligence arises solely as a function of physical maturation. Instead, he saw intelligence as something that adapts to its environment over time, through the active par- ticipation of both the child and his or her environment (Piaget, 1970/1988). We will review a few general principles of Piagetian theory before describing specific cognitive stages of development.  Chapter 14 Cognitive Development Through Adolescence 501 General Principles Piaget’s long-standing interest in the development of children’s thinking actu- ally began, in a way, in his own childhood, as he studied and wrote about birds, fossils, and mollusks. In adolescence, he added the study of philosophy to his ever-widening circle of interests. His knowledge of natural history and science led him to think about psychological concepts, such as thinking and intelli- gence, in very ethological terms. Specifically, Piaget saw how any organism adapts to its environment as sharing many similarities to how human children’s intelligence develops. Both processes involve a sort of adaptation. Intelligence, Piaget believed, represented an adaptation of mental structures to the physical, social, and intellectual environments (Ginsburg & Opper, 1988). Piaget saw children as active participants in their own development. He rejected the idea that cognitive structures somehow slowly emerge or unfold, or that they are thrust on an unsuspecting and passive child by a parent, teacher, or other aspect of the environment. Instead, Piaget believed that children construct their own mental structures, the building blocks of cogni- tion and intelligence, through a constant and active series of interactions with their environment. Construction of mental structures begins shortly after birth. The infant comes into the world with very little cognitive “equipment.” Indeed, about all the neonate has is a set of reflexes, including such things as sucking and grasp- ing. These reflexes (the precursors to mental structures) encounter the envi- ronment, and the interaction of the two results in the gradual growth and change of the original reflexes. Throughout the process, the infant (and later, the child, and still later, the adolescent) actively participates through practice, experimentation, and accidental discovery. Piaget saw the major mechanism of development as the adaptation of men- tal structures. The analogy here is to evolutionary adaptation—how animals, over several generations, evolve new structures or behaviors that better fit their current environment. Adaptation in the Piagetian sense consists of two distinct but interrelated processes: assimilation and accommodation. Piaget (1970/1988) defined assimilation as the “integration of external elements into evolving or completed structures” (p. 7). The idea here is that mental structures are applied to new objects in the world. An infant who has a structure (Piaget called it a scheme) for sucking may at first suckle only at the mother’s breast. However, when new objects are placed within easy reach of his mouth, the infant may apply that structure to the new object, say, a bent finger. We say the finger has been assimilated to the sucking scheme. Accommodation, by contrast, involves changing the structures to fit new objects. A finger has a different shape and texture from a breast and must be 502 Part V Individual and Situational Differences in Cognition Image not available due to copyright restrictions sucked in a slightly different way. Each time the infant sucks on a new object, she changes, even if ever so slightly, the sucking scheme. That internal change in the structure is known as accommodation. Assimilation and accommodation are always present, at least to some degree, in every act of adaptation, because it is impossible for one to exist in the absence of the other. Optimally, the two are balanced, or in equilibrium. Piaget assumed that all cognitive functioning is organized in a particular manner at every level of development. By “organized,” Piaget meant to suggest that the various mental structures have some relationships to one another. With development, these relationships become more complex, more numerous, and more systematic. Although some organization among mental structures always exists, the specific interrelationships of mental structures change in different developmental stages. As a result, the ways in which the child understands the world also change with development. According to Piaget, this is because knowledge is always acquired and interpreted through whatever mental structures currently exist.  Chapter 14 Cognitive Development Through Adolescence 503 Stages of Development Piaget described four major periods (we will refer to them here as stages) of development. Some of these stages can be divided into a series of substages. For our purposes, we will concentrate on the four main stages, but interested students can learn more about the substages by consulting other sources (such as Ginsburg & Opper, 1988; Miller, 2002). The Sensorimotor Stage The first stage is the sensorimotor stage, beginning at birth and lasting roughly 18 months. The stage is so named because Piaget believed that an infant in this phase of development experiences the world almost entirely through sen- sory and motor experiences. According to Piaget, knowledge gained during this stage is acquired through, and is often equivalent to, sensation or action. The infant is described as lacking the capacity for mental representation. Thus all experience must happen in the here and now and must be centered on things that are present. The implications of this description are profound. They suggest that infants experience the world in ways completely different from those of older children or adults. Older children can have thoughts, conscious recollections of past experiences, and ideas about the past and future. All these abilities, however, require the capacity for mental representation. The infant, lacking the capac- ity for mental representation, cannot have any of these things. For the infant, thought is action or sensation, because there is no means of representing thought except through action or sensation. Piaget saw all cognitive development as beginning with the infant’s biolog- ical heritage: a simple set of reflexes such as sucking and rooting (moving the head in the direction of a touch on the cheek). This primitive “mental equip- ment” slowly changes and evolves as the infant matures and acquires many experiences in the world. Sucking, for instance, is applied to many different objects—fingers, toys, keys, strands of hair—demonstrating assimilation of new objects to the sucking scheme. Each of these objects has a different shape, size, and texture, so the way the infant sucks on each one is slightly different, forcing accommodation of the sucking scheme. Gradually, over a period of 18 months, the schemes grow more complex, are executed more smoothly and more efficiently, and become integrated with other developing schemes. At first, for example, infants may suck only on ob- jects placed near their mouth. Later in infancy, they learn how to grasp objects in front of them. As these two schemes—sucking and grasping—develop, they can also be coordinated so that older infants can reach out for an interesting novel object, pull it toward them, and place it in their mouth as a new thing to suck on. 504 Part V Individual and Situational Differences in Cognition One of the important developments in the sensorimotor stage is the acquisition of the con- cept of object permanence. An adult holds a novel and interesting toy in front of a seated infant, at- tracting his attention. As the infant reaches for the toy, however, the adult frustrates his attempts to grab it by first moving it out of reach, then blocking the infant’s view by placing a screen between the infant and the toy. The reaction of the 4-month-old infant is quite surprising: A few seconds after the toy disappears from sight, the infant looks away and shows no inclination to search for it. Piaget interpreted this reaction as follows: Having no capacity for mental represen- tation, the infant experiences objects only when they are present in the here and now. Quite liter- Nancy J. Ashmore ally, objects out of sight are also objects out of mind. An older infant (say, around 8 months) According to Piaget, the sucking scheme demonstrates more, if not complete, under- demonstrated by this infant will undergo standing of the idea that objects continue to assimilation and accommodation. exist even when they are not immediately in view. An infant at roughly this age continues to search for objects that are partly hidden. A slightly older infant (10–12 months) even searches for completely hidden objects. This is also about the time that infants start to show stranger anxiety—looking fearfully around for a parent who has left the room and showing wariness of the person left with them (often Images not available due to copyright restrictions  Chapter 14 Cognitive Development Through Adolescence 505 a hapless babysitter). The infant seems to treat the missing parent as yet another object that has disappeared—except in this case, the emotional consequences of the disappearance are much greater than they are for a ball or other toy. Another important developmental achievement in the sensorimotor period is the increasing intentionality and understanding of causality. Piaget’s descrip- tion of this aspect of development (as well as other aspects) involves the concept of circular reactions—behaviors that are repeated over and over. At first, young infants (1–4 months) display primary circular reactions—behaviors that are set off by chance, are centered on the infant’s own body, lead to an interesting (from the infant’s point of view) result, and are then continued. Thumb sucking is an example. Young infants’ thumbs find their way into their mouths almost at random. Once a thumb is properly situated, however, most infants keep it there and continue to suck on it. Secondary circular reactions emerge at roughly 4 to 8 months. These are ori- ented to objects outside the infant’s body and may include such things as shak- ing a rattle to produce a noise or banging the side of a crib to make a mobile attached to the crib move. At around 18 months, tertiary circular reactions appear. Piaget compared the infant’s tertiary circular reactions to scientific experiments. Here the infant begins with a goal in mind—to produce an inter- esting result. For example, he may drop a toy over the side of his high chair and watch it fall. This interesting result leads the infant to experiment, varying dif- ferent aspects of the situation. Different toys are dropped, from varying heights, on different sides. Other things—bottles, cups of juice, and bowls of food—can also be dropped, to the infant’s glee and the caretaker’s frustration. The sensorimotor period ends after approximately 18 to 24 months. Having begun her cognitive life with little more than reflexes, the infant now has a new understanding of objects and their existence independent of her actions, a better sense of her own ability to affect things in the world, and most impor- tant, the mental ability to represent objects, events, and people. Older infants show some recall of past events. For example, one of Piaget’s daughters, Jacqueline, was able at about 14 months to re-create many of the features of a temper tantrum she had seen a little boy produce 12 hours before (Miller, 2002). This event displays a number of cognitive abilities—the ability to store and recall information and the ability to imitate these behaviors at a later time (deferred imitation)—all of which require the existence of mental representa- tion. All these achievements are necessary for the cognitive tasks to be con- fronted in the next period of development. The Preoperational Stage The next stage of development, lasting from roughly age 18 months to roughly age 7 years, is known as the preoperational stage of cognitive development. 506 Part V Individual and Situational Differences in Cognition Armed with the capacity for mental representation, the preoperational child understands the world in new and more complex ways than did the infant or toddler. In particular, the preoperational child has acquired the semiotic func- tion, the ability to use one thing to represent or stand for another. The child now shows a great deal of symbolic functioning: pretending to drink from an empty cup; cradling a doll or stuffed toy as if it were a baby; “riding” on a “pretend horse” made of a stick. A second, and related, ability is the use of language. Children at this age are busy rapidly acquiring a vocabulary of words that “stand for” real objects or events in the world. In this sense, language requires symbolic thought capacities. Piaget saw children’s language development as a reflection, rather than a cause, of their intellectual structures. The child’s capacity for representational thought now al- lows a greater variety of cognitive activities and thus a greater range of exploration. Children can now play in more complex ways than ever before, including ele- ments of fantasy and reenactment. They can talk with others about their experi- ences, those in the present and those that have previously happened. They can also talk about and begin to plan for future events, such as a trip to the store after nap time, and use language to guide themselves through challenging tasks. At the same time, as the name of the stage suggests, there are important gaps in children’s thinking. In fact, the name preoperational suggests a contrast with the later period of concrete operations. Preoperational children are typi- cally described as lacking mental operations that older children have (to be described later; Gelman, 1978) and, consequently, as having significant limits on their thinking. Of course, adults have been shown throughout the book to have limits on their thinking, too. Apparently, though, the greater limitations to which children seem subject change their cognitive performance in very no- ticeable ways. Piaget described the preoperational child as egocentric in his thinking. Children of this age apparently have a difficult time taking into account any viewpoint other than their own. For example, a 4-year-old coming home from nursery school might tell his mother, “Ted did it,” not explaining who Ted is or what he did. According to Piaget, this egocentric language results from his inability to take his mother’s perspective, to understand that his mother might not know who Ted is. The 4-year-old assumes that everyone knows what he knows, sees things as he does, and remembers what he remembers. An experimental demonstration of egocentrism came from the work of Piaget and Inhelder (1967). They presented children with a three-dimensional model of three mountains. Arranged around the mountains were different objects, such as a small house and a cross, that were visible from some angles but not others. Preschool children were asked to describe whether an observer (a small wooden doll) on the other side of the table could see particular objects (see Figure 14-1). Children typically responded that the observer could see everything the child could see, failing to take into account the observer’s different vantage point.  Chapter 14 Cognitive Development Through Adolescence 507 FIGURE 14-1 Example of the stimulus apparatus for the three-mountain task. Preoperational children’s thinking has also been described as centered on their perceptions of the world. That is, the children attend to, or focus on, only a limited amount of the information available at any given point (Ginsburg & Opper, 1988). Moreover, the thought of preoperational children is said to be static, focusing on states rather than transformations or changes. Finally, preop- erational children are described as lacking reversibility, the ability to “mentally reverse” an action. One well-known illustration of these aspects of preoperational thinking comes from Piagetian number conservation tasks. They work as follows: The experimenter sets two rows of checkers in front of the child, one set black and one red, each containing five checkers. Initially, the checkers in each row are set out in one-to-one correspondence (each black checker is lined up with a red checker), and the child judges both rows of checkers to be equal in num- ber. Next the experimenter spreads out one of the rows of checkers (see Fig- ure 14-2) and asks the child which row has more, or if the two rows still have the same number of checkers. The typical 4-year-old responds that the longer row has more checkers than the shorter row. He has not appreciated that operations such as moving checkers around the table are number irrelevant: They do not affect the numerosity of the rows. 508 Part V Individual and Situational Differences in Cognition FIGURE 14-2 Depiction of conservation of number task. Initial display After transformation Conservation of number One explanation for this puzzling response is that the child is overwhelmed by what the two rows of checkers look like. One row does indeed look “bigger” (longer) and perhaps therefore more numerous. The child has centered on the length of the rows and ignored the density (the space between checkers) or the numerosity. The child has paid attention to what the rows of checkers now look like (the static stimulus display) and has ignored the fact that the transformation Nancy J. Ashmore To a preoperational child, it might seem as though the row of pegs closer to him contains fewer than the row farther away.  Chapter 14 Cognitive Development Through Adolescence 509 involved did not add or subtract any checkers and thus could not affect the number of checkers in either row. Finally, the child has not mentally reversed the action of spreading out one row of checkers—to see that he can mentally push the less dense row into its original formation, in which the two rows of checkers are numerically equal. According to Piaget, the things preoperational children lack—the abilities to decenter, to focus on transformations, and to reverse actions—leave them with little to rely on other than their perceptual experience. The Concrete Operations Stage Children’s thinking changes, again dramatically, when they move into the next stage of development, the period of concrete operations, around the age of 7 until about the age of 11 or 12. At this point, the child can attend to much more information than before and therefore can take into account more than one aspect of a situation. Piaget described this aspect of children’s thought as decentered, to draw a contrast with the centered nature of preoperational thought. Concrete-operational children also can pay attention to transformations and not just to initial and final states. The conservation task provides a familiar example. The child who conserves number moves beyond his perception, recognizing that certain changes (for example, in number, or in amount of liquid) result only from certain transfor- mations, such as adding or taking away, and not from others, such as spreading out or changing shape. Piaget says that this child’s thought shows reversibility. A concrete-operational child can construct (as the preoperational child cannot) a mental representation of the transformation and of the “reverse” of the transfor- mation (moving checkers to their original position, pouring a liquid back into its original container) and can use this knowledge to judge correctly the relative numbers or amounts. Another ability that matures during the stage of concrete operations is classi- fication. The younger, preoperational child has a great deal of trouble consis- tently sorting a group of objects into categories (for example, all the round things, all the square things; or all the blue things, all the red things). The preoperational child has difficulty maintaining a consistent basis of classification. He may start out sorting wooden blocks on the basis of shape but midway through the task start sorting on the basis of color. The groups he ends up with will include blocks that vary in both shape and color. The older, concrete operational child is much more consistent and hence better able to keep track of the task. The typical concrete-operational child seems like a very mature thinker when compared with a younger child; however, there are still areas of limitation in this period of development. In particular, the child has difficulty thinking in abstract terms. Her thinking is limited to actual or imagined concrete things. And, when compared with an older adolescent, her thinking is less systematic. 510 Part V Individual and Situational Differences in Cognition The Formal Operations Stage The final stage of cognitive development, which begins around puberty, is that of formal operations. Adolescents show much more systematic thinking. For in- stance, when given a number of beakers containing different liquids and asked to determine how they can be mixed together to produce a liquid of a certain color, adolescents do a number of things that younger children do not. First, they can generate all the possible combinations of liquids and often do so in a systematic way. They test one combination at a time and keep track of the results of each one. They are better able to isolate and hold constant all factors except one, and to report on their results accurately. This may be why middle school and high school students seem so much better in science classes at designing and carrying out experiments. The formal-operational thinker is also able to think more abstractly than the concrete-operational thinker. Adolescents now see reality as one of several pos- sibilities and can imagine other kinds of realities. This new liberation of thought has been described as one of the sources of adolescent idealism and political awakening. Adolescents’ awareness of different possibilities opens up for them many different possible paths to the future because they can “think beyond old limits” (Moshman, 2005). Typically, adolescents are also more adept at logical thinking than are younger children. In part, this has to do with their ability to think abstractly and to reason from arbitrary propositions such as “If all the X’s are Y’s, and none of the Y ’s are Z’s, then at least some of the X’s are not Z’s.” Adolescents, unlike younger children, are able to understand the idea of logical necessity in reason- ing. This is the notion that for some arguments, if the premises are true, then the conclusion is guaranteed to be true as well (Moshman, 2005). Logical thinking also derives from a newly emerging ability Piaget called reflective abstraction (Piaget, 1968). Adolescents can, for the first time, acquire new knowledge and understanding simply from thinking about their own thoughts and abstracting from these reflections. By doing so, they may begin to notice inconsistencies in their beliefs. Reflective abstraction is also useful in other realms of thinking, notably those of social and moral thinking. The adolescent is now quite capable of taking the points of view of others and trying to think about issues as others would. There is much debate over whether all adolescents ever reach the period of formal operations, although Piaget (1972) maintained that they do. However, Piaget did not mean to suggest that even those who do would always display their highest competence. Instead, his idea was that adolescents who acquire formal operations have the ability to think abstractly, systematically, and logi- cally, even if they do not always do so. Piaget’s theory of cognitive development thus describes how thought evolves from simple reflexes to an organized, flexible, logical system of internal  Chapter 14 Cognitive Development Through Adolescence 511 mental structures that allow thinking about a wide variety of objects, events, and abstrac- tions. A child at each stage of development has a remarkable set of abilities but often (especially in stages before formal opera- tions) faces several limitations in thinking. The mental structures that allow and orga- nize thought develop slowly through the child’s active exploration of the world. Reactions to Piaget’s Theory Piaget’s major writings date from the 1920s, although his fame in the United States was not really established until the early 1960s. Halford (1989) described the 1960s as a period of intense optimism about Piagetian Nancy J. Ashmore theory in this country as many psychologists and educators sought ways of applying it to problems of designing appropriate educa- According to Piaget, hypothetical and tional curricula for children and adolescents deductive reasoning typical of that required of varying ages. However, beginning around for scientific experimentation awaits the the 1970s, enthusiasm for Piaget’s ideas began development of formal operations. to fade as a number of studies appeared to disconfirm some of the theory’s predictions (see Gelman & Baillargeon, 1983, and Halford, 1989, for reviews; see Newcombe, 2002, and Roth, Slone, & Dar, 2000, for other perspectives on Piagetian theory). Many researchers were concerned about methodological problems in Piaget’s studies. His reports of sensorimotor cognitive development, for exam- ple, were based on the observation of only three infants, all Piaget’s own children (Miller, 2002). Accordingly, it is hard to know how free from bias or overinterpretation Piaget’s observations were, although later research has replicated nearly all the phenomena he reported (Ginsburg & Opper, 1988). In work with older children and adults, Piaget again employed the clinical method, often modifying the tasks or questions for each child in response to his or her performance or explanation. Although this approach allows a great deal of flexibility, it also opens the door to various threats to validity, especially the possibility that the experimenter will unconsciously and subtly provide the child with cues or leading questions. Siegel and Hodkin (1982) pointed out other methodological problems in the tasks Piaget developed. Many seem to require much more than simply the understanding of the concept under investigation. Children in a conservation 512 Part V Individual and Situational Differences in Cognition task, for instance, not only must observe the materials undergoing different transformations and make the correct judgments but also must explain their answers carefully and, in some cases, resist countersuggestions from the experimenter. Siegel and Hodkin argued that when a child is asked the same question several times, to assess the particular cognitive ability with different stimuli, the child may change the answer because he or she believes the adult is asking the question again because the first answer was wrong. Usually adults do not repeat a question when the answer is correct, but only when it is wrong. “[The child’s] response vacillation may be interpreted as a sign of unstable cog- nitive structures, but it may also reflect children’s eagerness to provide the answers they think the adult is seeking” (p. 59). Other investigators and theorists have raised problems with parts of Piaget’s theory. Many have agreed that evidence for distinct stages of cognitive devel- opment is not strong (Brainerd, 1978; Miller, 2002). A strict interpretation of stage theory would require, for example, that all stage-related abilities appear together, a prediction not well borne out. There is also an arguable lack of evi- dence for the specific cognitive structures that Piaget described as underlying the different stages (Halford, 1989). Further, a variety of empirical studies have demonstrated a great deal of competence and knowledge among young children for which Piaget’s theory has difficulty accounting. Nonetheless, even his sharpest critics acknowledge a tremendous debt to Piaget. Most investigators admire the wide-ranging scope of the theory and the cleverness Piaget showed in devising tasks to reveal important aspects of children’s thinking at different periods in development. NON-PIAGETIAN APPROACHES TO COGNITIVE DEVELOPMENT Many psychologists who study cognitive development appreciate the keen observations that Piaget reported but do not accept his interpretation of their underlying causes. In particular, many believe that cognitive development does not proceed through a series of qualitatively different stages or periods nor that qualitatively different intellectual structures underlie cognition at different periods. Instead, these investigators assert that cognitive skills and abilities emerge or are acquired gradually. Many of these psychologists use adult models of cognitive processes as a framework within which to understand how children process information. Many take information-processing models, such as those described in earlier chapters, as the starting point for a model of cognitive development. The basic strategy is to discover how information-processing models of adult cognition must be modified to describe and explain the performance of children of dif- ferent ages and abilities.  Chapter 14 Cognitive Development Through Adolescence 513 As with models of adult cognition, information-processing models of chil- dren’s cognition use the digital computer as a metaphor for the child’s mind. Information presented to the child (either explicitly or implicitly) can be regarded as input. Just as computers have various storage devices (buffers, disks), so too children are assumed to have one or more distinct memory stores. Just as computers retrieve information from their stores, so too chil- dren are assumed to be able to access (at least some of) their information and to use it in a number of cognitive tasks, including calculation, classification, identification, and integration. Finally, just as computers write information on disks or on printers or terminal screens, so too do children often produce out- put of one sort or another: a verbal response, a drawing, a gesture, or some other behavior. Other psychologists focus on physiological (particularly neurological) and other innate factors that contribute to cognitive development. These psycholo- gists begin with the premise that young infants do not have “blank slates” for minds but instead bring to their cognitive life certain mental structures that are present from birth. Not surprisingly, these psychologists investigate the cogni- tive competencies of young infants and toddlers, who presumably have had relatively little opportunity for learning cognitive skills. Still other developmental psychologists are rediscovering another “great theorist” of cognitive development, the Russian psychology Lev Vygotsky (1896–1934). Vygotsky’s theory differs from Piaget’s mainly in that he sees as inseparable the child and the context in which that child functions. Thus a child’s ability to understand the concept of the permanent object, or to con- serve number, or to reason systematically cannot be evaluated by focusing on the child alone. Instead, Vygosky held, the environment, both physical and social, within which an activity is carried out must be taken into account. Vygotsky introduced the concept of the “zone of proximal development” to account for the fact that children can often perform in more advanced ways with guidance or collaboration from an adult (Miller, 2002). When a more competent individual collaborates with a younger, less cognitively mature child, that child’s performance is typically enhanced, even if the interaction is informal (Rogoff, 1990). Developmental psychologists in the Vygotskian tra- dition, therefore, are more apt to investigate children working with adults on everyday tasks. Thus their work falls within the ecological paradigm discussed in Chapter 1. In this section, we will review a few examples of work that departs from the Piagetian tradition. The examples span a range of types of cognitive tasks, as well as different periods of development. Although they represent only a minute proportion of the possible examples of important research on cognitive development, they provide a sense of the kinds of questions cognitive develop- mental psychologists ask and how they seek answers. 514 Part V Individual and Situational Differences in Cognition Perceptual Development in Infancy We saw in Chapter 3 that our perceptual activities are crucial to our acquiring information from and about the world around us. It behooves a cognitive psychologist interested in perception, then, to understand how perceptual abil- ities, skills, and capacities develop. Work with infants conducted by Renee Baillargeon traces the development of perceptual understanding of objects and events across age groups (Baillargeon & Wang, 2002). Consider the ability of infants to understand the concept of physical support; for example, one object can physically support another if (typically) the supporting object is under- neath the supported object and if enough of the supported object’s surface makes contact with the supporting object. To make this more concrete, consider Figure 14-3. Imagine showing a research participant one of two events. In the top row, depicting a possible event, a gloved hand pushes one box (with a smiley face) across the top of Text not available due to copyright restrictions  Chapter 14 Cognitive Development Through Adolescence 515 another one. This is called a possible event because in real life it could easily happen. The bottom row depicts an impossible event, one that under normal circumstance could not occur (the experimenters used sleight of hand to make it occur): A box is pushed across the top of a supporting box until only 15% of its bottom surface rests on the supporting box. What do infants do when they witness these two events? Predictions from Piagetian theory should be that young infants (below 10 months, say), would see both events as equally possible. But they don’t. Their facial expressions reg- ister surprise (as rated by research assistants who can’t see what the infants are looking at). In fact, the results show a developmental pattern quite at odds with Piagetian theory: Our results indicate that by 3 months of age, if not before, infants expect the box to fall if it loses all contact with the platform and to remain stable other- wise. At this stage, any contact between the box and the platform is deemed sufficient to ensure the box’s stability. At least two developments take place between 3 and 6.5 months of age. First, infants become aware that the locus of contact between the box and the platform must be taken into account when judging the box’s stability. Infants initially assume that the box will remain stable if placed either on the top or against the side of the platform. By 4.5 to 5.5 months of age, however, infants come to distinguish between the two types of contact and recognize that only the former ensures support. The second development is that infants begin to appreciate that the amount of contact between the box and the platform affects the box’s stability. Initially, infants believe that the box will be stable even if only a small portion (for example, the left 15%) of its bottom surface rests on the platform [see Figure 14-3]. By 6.5 months of age, however, infants expect the box to fall unless a significant portion of its bottom surface lies on the platform. (Baillargeon, 1994, pp. 133–134) Recall also from Chapter 3 our discussion of the Quinn et al. study (2002), showing that infants aged 3 months do not show evidence of using Gestalt principles of similarity, whereas infants aged 6–7 months do. These authors suggest that different Gestalt principles become functional at different times in an infant’s development. Toddlers’ Acquisition of Syntax In Chapter 10, we discussed several aspects of language abilities and usage. Each of these aspects shows interesting developmental changes. Most psy- chologists and linguists who study language development agree on a proposition that at first might seem startling: Children do not learn syntax (Chomsky, 1959). That is, the way in which syntax develops from infancy through adolescence is 516 Part V Individual and Situational Differences in Cognition difficult to account for in terms of simple learning mechanisms. One reason is that syntactic development typically occurs in a very short time frame—in only a few years. Further, children undergoing language development hear many different utterances of a language—from parents, siblings, teachers, and oth- ers. However, what children appear to acquire are not specific sentences or utterances but rather the underlying rules that govern a particular language. As I hope Chapter 10 convinced you, the rules that govern a language are complex and very difficult to articulate. Thus it is quite unlikely that parents and other adults are teaching these syntactic rules. Moreover, studies of parents interacting with their children demonstrate that parents rarely correct syntactic errors of children’s speech (such as “Yesterday I goed to the playground”), responding instead to the content of what is said (such as “No, honey, yesterday we went to the zoo”) (Ingram, 1989). These and other arguments cause developmental psychologists to speak of language acquisition rather than language learning. Many developmental psychologists studying language acquisition agree with Chomsky’s (1957, 1959) assertions that people are born with language univer- sals; that is, they are biologically prepared to acquire a human language (as op- posed to a computer language or other kind of artificial language). The actual language a child acquires almost certainly is subject to environmental influ- ences: Children born to English speakers invariably acquire English, and those born to parents who speak Hungarian unfailingly acquire that lan- guage. Chomsky believes people have a language acquisition device (LAD), an inborn set of mechanisms and knowledge that requires only an environmen- tal trigger to be set in motion. The environment controls which language(s) is (are) acquired, but the capacity to acquire a human language is regarded as innate. Although children typically begin to use recognizable words at around a year of age, usually not until their second year do they begin producing utter- ances of more than one word. It is not possible to speak of syntax in a toddler’s language until he produces multiword utterances, simply because it is not pos- sible to structure a one-word utterance in different ways. If children’s two-word utterances had absolutely no structure, then what we should observe are random pairings of words in a child’s vocabulary. In fact, what we observe is quite the opposite: Children’s two-word utterances display a considerable amount of regularity. Consider Box 14-1, which presents a number of two-word utterances spoken by my niece, Brandi Lee, when she was about 18 months old. You’ll notice that certain words or phrases, such as “Rockabye” or “Oh deah,” always occur initially in the utterance; that other words or phrases, such as “down” or “didit,” always occur at the end of the utterance; and that cer- tain other words, such as “Dassie,” “Mummy,” and “Santa,” occur either initially or at the end of the utterance.  Chapter 14 Cognitive Development Through Adolescence 517 Box 14-1 Sample Two-Word Utterances Dassie (her word for “Kathie”) down. (meaning “Kathie, sit on the floor”) Mummy down. (meaning “Mommy, sit on the floor”) Rockabye baby. Rockabye turkey. Rockabye Santa. Oh deah (dear) Santa. Oh deah Dassie. Oh deah Mummy. Oh deah turtle. Mummy didit. (“didit” meaning, roughly, to have performed an action) Dassie didit. Brannie (her word for “Brandi”) didit. Braine (1963) hypothesized a pivot grammar to account for these regularities. Braine argued that children begin to form two-word utterances by first somehow selecting a small set of frequently occurring words in the language they hear. These words are called “pivots.” Children’s knowledge about pivots includes not only the pronunciation and something about the word’s meaning but where in an utterance the pivot should appear. Other words the child uses are called “open” words. Braine argued from data much like that in Box 14-1 that toddlers form “syntactic” rules of the following sort: “Pivot1 + Open” or “Open + Pivot2,” where Pivot1 includes all sentence-initial pivots (such as “Oh deah,” “Rockabye”), and Pivot2 includes all sentence-final pivots (such as “didit,” “down”). Braine’s (1963) pivot grammar accounts for some of the regularities appar- ent in the speech of some children. However, work by other investigators (Bowerman, 1973; Brown, 1973) soon showed that it fails to account for the utterances of all children. Although current consensus is that the grammar is at best incomplete and in many cases incorrect, some investigators have argued that it may provide some useful ideas about how children begin to construct a grammar from the language they hear around them (Ingram, 1989). Roger Brown (1973) took a different tack in accounting for regularities in children’s two-word utterances. Brown asserted that children at the two-word stage are constructing their utterances not by following rules of syntax but by using a small set of semantic relations. Table 14-1 presents the semantic rela- tions he proposed. Brown argued that this particular set of relations is an out- growth of the knowledge toddlers of this age should have about the world. He believed that children at this point in development focus on actions, agents, and objects and are concerned with issues such as where objects are located and when and how they can disappear and reappear. As such, Brown’s proposals fit nicely with the Piagetian view of sensorimotor development (Ingram, 1989). 518 Part V Individual and Situational Differences in Cognition Table 14-1 Proposed Semantic Relations for Early Grammars Relation Definition and Examples 1. Nomination The naming of a referent, without pointing, usually in response to the question “What’s that?” Often indicated with words such as “this,” “that,” “here,” “there.” (Also see “Demonstrative and Entity” below.) 2. Recurrence The reappearance of a referent already seen, a new in- stance of a referent class already seen, or an additional quantity of some mass already seen, e.g., “more” or “another” X. 3. Nonexistence The disappearance of something that was in the visual field, e.g., “no hat,” “allgone egg.” Semantic Functions 4. Agent + Action The agent is “someone or something, usually but not necessarily animate, which is perceived to have its own motivating force and to cause an action of process” (p. 193), e.g., “Adam go,” “car go,” “Susan off.” 5. Action + Object The object is “someone or something (usually some- thing, or inanimate) either suffering a change of state or simply receiving the force of an action” (p. 193). 6. Agent + Object A relation that uses the two definitions above. It can be considered a direction relation without an intervening action. 7. Action + Location “The place or locus of an action” (p. 194), as in “Tom sat in the chair.” Often marked by forms like “here” and “there.” 8. Entity + Locative The specification of the location of an entity, i.e., any being or thing with a separate existence. These take a copula in adult English, e.g., “lady home” meaning “the lady is home.” 9. Possessor + Possession The specification of objects belonging to one person or another, e.g., “mommy chair.” 10. Entity + Attribute The specification of “some attribute of an entity that could not be known from the class characteristics of the entity alone” (p. 197), e.g., “yellow block,” “little dog.” 11. Demonstrative and Entity The same as Nomination except that the child points and uses a demonstrative SOURCE: Ingram (1989, p. 287).  Chapter 14 Cognitive Development Through Adolescence 519 One problem with Brown’s approach is that it requires an adult to interpret what the child intended to communicate at the time of the utterance. It makes adults interpret children’s language in terms of adult assumptions and beliefs, and it assumes that adults and children use language to refer to events and objects in the world in similar ways. Ingram (1989) pointed out that this assumption can be erroneous. Much work since the 1970s has attempted to avoid problems in both syntac- tic and semantic approaches. The complexity and specificity of many of the existing models preclude their being discussed here. However, there is agreement that even from the early days of language use, children’s utterances show many regularities. Because many of the regularities observed come from children of very different cultures and language communities, it is further hypothesized that children’s language acquisition cannot be the simple result of learning. Preschoolers’ Use of Memorial Strategies Many researchers who study the development of memory in children have been struck by the different approaches to memory tasks adopted by younger and older children. A particularly striking difference concerns the use of memorial strategies, defined as “deliberate plans and routines called into ser- vice for remembering” (Brown, Bransford, Ferrara, & Campione, 1983, p. 85). One important remembering strategy is rehearsal of the to-be-remembered material. Rehearsal can involve silent or out-loud repetition and is thought to maintain information in working memory, making it more likely to be stored for longer periods of time (Ornstein & Naus, 1978). A number of studies (reviewed by Ornstein & Naus, 1978) have repeatedly demonstrated two things. First, younger children (preschoolers and younger ele- mentary school–age children) are less likely to rehearse material than are older children (older elementary school–age children and middle school–age children). Second, when children who do not spontaneously rehearse can be induced to do so, their memory performance often rises to the level of similar-age children who do rehearse spontaneously. A classic study by Flavell, Beach, and Chinsky (1966) demonstrated the first of these points. The authors worked with children in kindergarten and the second and fifth grades. Each child was shown two sets of seven pictures and was asked to point to the pictures in the same order that the experimenter did. In one condition, the wait was 15 seconds between the time the experimenter finished pointing and the time the child was asked to re-create the order. The children wore special “space helmets” that prevented them from looking at the pictures or seeing the experimenter but allowed the experimenter to ob- serve whether they were verbalizing the items they had to remember (one of the experimenters, trained in lip reading, spent each session watching and 520 Part V Individual and Situational Differences in Cognition listening for such verbalizations). Results were dramatic: Very few of the kinder- garten participants showed evidence of rehearsal; a little more than half of the second-graders and almost all the fifth-graders did show such evidence. A later study (Keeney, Cannizzo, & Flavell, 1967), using a similar procedure, illustrates the second point. These researchers found that 6- and 7-year-old “rehearsers” performed significantly better in recalling information than same- aged “nonrehearsers.” When the nonrehearsers were later trained to rehearse, their performance became indistinguishable from that of the initial “rehearsers.” However, when left to their own devices the initial “nonrehearsers” abandoned the rehearsal strategy. Brown et al. (1983) believed the use of rehearsal during early childhood is fragile, disappears easily, and occurs under only very limited circumstances (p. 94). Other research on memory development has shown that children’s perfor- mance on a memory task is often a function of their preexisting knowledge of, and expertise with, the materials of the memory task. Michelene Chi (1978) demonstrated this in a study with children (in grades 3 through 8) with chess tournament experience and adults with casual experience with chess. When given standard digit-span tasks, the adults tended to outperform the children. However, when the memory task involved recalling positions of chess pieces on boards, the children outperformed the adults. One possible explanation could be that their knowledge allowed the chess-experienced children to notice more relationships between chess pieces (such as “the king’s rook is attacking the queen”), facilitating more retrieval cues than were available to the less experienced adults. Conceptual Development in Early Childhood The subject of how children acquire and structure knowledge is the focus of researchers studying conceptual development. Susan Gelman and her col- leagues (Gelman, 1988; Gelman & Markman, 1986) have centered their in- vestigations on the question of how children make inferences about different kinds of things, given that they have some information about the category membership of those things. Let’s examine a specific example. Most of us know that although whales share a number of similarities with various kinds of fish (they swim, they live in water, they are often found in aquariums, they have an overall shape that is fishlike), they are in fact mammals (whales are warm-blooded and bear live young). As adults, we know that a whale must be categorized on the basis of something other than perceived features. The question is, do children know this too? Notice that the Piagetian view would predict that preschool children, being “perceptually bound,” would probably perform the classification solely on the basis of how the thing to be classified appears.  Chapter 14 Cognitive Development Through Adolescence 521 FIGURE 14-4 Stimuli from Gelman and Markman (1986). SOURCE: Gelman and Markman (1986, p. 188). In a series of studies, Gelman and Markman (1986) showed children sets of three pictures like the one shown in Figure 14-4. Each set was carefully con- structed so that the third picture looked like one of the first two pictures but was really in the same category as the one it did not resemble. Note, for exam- ple, that in Figure 14-4 the owl looks more like the bat but is really (to a knowl- edgeable adult) in the same category as the flamingo (both the owl and flamingo are birds; the bat is a mammal). Children were given information about the first two pictures in a set (for example, “This bird’s heart has a right aortic arch only” [as the experimenter points to a picture of the flamingo]; “This bat’s heart has a left aortic arch only” [as the experimenter points to a picture of the bat]). While looking at the third picture (for example, an owl shaped like the bat), the child was asked to predict what would be true of the owl’s heart. Contrary to Piagetian predictions, 4-year-old children based their inferences on category membership rather than on physical appearance (when the two were in conflict) approximately 68% of the time. In further work, Gelman (1988) investigated the constraints on children’s inferences based on category membership. Preschoolers and second-graders first learned presumably new facts about objects (for example, “This apple has pectin inside”) and then were asked whether these facts were true of other items of varying similarity (such as other apples, a banana, a stereo). Gelman used two kinds of categories: natural kinds (naturally occurring objects, such as animals, plants, fruits, and other things not constructed by humans) and artifacts (ob- jects constructed by people usually to perform a certain function, such as chairs, tools, computers). Recall from Chapter 8 that adults treat these two kinds of concepts differently. The question was, do children also treat these two kinds of concepts differently, and if they do, at what age do they start to make the distinction? Gelman (1988) found that children (preschoolers and second-graders) con- sistently drew the inference that items in the same category shared the new 522 Part V Individual and Situational Differences in Cognition property they had just learned about. For example, on being told that “apples have pectin,” all the children were also likely to infer that a banana had pectin, too. They were much less likely to infer that a stereo had pectin. Apparently, then, even preschoolers use their knowledge of category membership to make inferences about what kinds of properties different things might have. It is in- teresting that second-graders were sensitive to the natural-kind/artifact dis- tinction and drew more inferences with natural-kind concepts. Preschoolers, in contrast, appeared relatively insensitive to the distinction. Gelman believed that this insensitivity resulted from their relative lack of deep knowledge about the objects being talked about. The Development of Reasoning Abilities in Middle and Late Childhood The final set of examples illustrating information-processing models of cog- nitive development describes the development of reasoning abilities. A clas- sic study by Osherson and Markman (1975) showed that first-, second-, and third-graders had apparent difficulty distinguishing between statements that were empirically true or false (that is, true in fact) and those that were logi- cally true or false (that is, true by necessity or definition). The experimenter showed children, adolescents, and adults small plastic poker chips in assorted solid colors. Children were told that the experimenter would be saying some things about the chips and that the children should indicate after each state- ment if it was true, false, or they “couldn’t tell.” Some of the statements were made about chips held visibly in the experimenter’s open hand. Other, similar statements were made about chips hidden in the experimenter’s closed hand. Among the statements used were logical tautologies (statements true by definition)—for example, “Either the chip in my hand is yellow, or it is not yellow”; logical contradictions (statements false by definition)—for ex- ample, “The chip in my hand is white, and it is not white”; and statements that were neither true nor false by definition but depended on the color of the chip. First-, second-, third-, and even sixth-graders did not respond correctly to tautologies and contradictions, especially in the hidden condition. They tended to believe, for example, that a statement such as “Either the chip in my hand is blue, or it is not blue” cannot be assessed unless the chip is visible. Tenth-graders and adults, in contrast, were much more likely to respond that even when the chip couldn’t be seen, if the statement was a tautology or con- tradiction the statement about it could be evaluated on the basis of form. These results were consistent with Piaget’s assertion that logical reasoning, particularly abstract, hypothetical reasoning, awaits the attainment of formal operations in adolescence.  Chapter 14 Cognitive Development Through Adolescence 523 A later study by Hawkins, Pea, Glick, and Scribner (1984) painted a differ- ent picture. These authors gave 4- and 5-year-olds a number of verbal syllo- gisms, such as “Pogs wear blue boots. Tom is a pog. Does Tom wear blue boots?” The syllogisms required logical reasoning. Contrary to expectation, the preschoolers could correctly answer many of the syllogisms and provide appro- priate justifications for their answers, especially if the problems were about make-believe animals, as in the example above. The authors believed these syllogisms in particular prevented the children from using their preexisting knowledge of animals (they had probably not had previous knowledge of, or experience with, a pog). With other syllogisms that were about real animals or objects, the children performed noticeably worse, especially when the premises in the problem were incongruent with the children’s preexisting world knowledge (for example, “Glasses bounce when they fall. Everything that bounces is made of rubber. Are glasses made of rubber?”). This result implies that although some ability to reason logically might begin in early childhood, much is undeveloped or unre- liable, at least until early adolescence, and maybe all through adulthood (see the discussion on adults’ reasoning abilities in Chapter 12). Another study, by Moshman and Franks (1986), supports this view. They gave children (fourth- and seventh-graders) a more stringent test of logical rea- soning competence. The children were presented with sets of three cards. On each card was typed an argument that was either (a) empirically true or false or (b) logically valid (the conclusion followed necessarily from the premises; see Chapter 12) or invalid. Participants were asked to sort the cards in as many ways as they could. In some of the studies, they were given definitions of the concepts of validity and were prompted to sort on this basis. However, even when specifically asked to do so, fourth-graders had difficulty sorting on the basis of validity (as opposed to, say, truth of the conclusion or format of the argument). Moshman and Franks interpreted these results as indicating that even when children can draw logically valid conclusions, they don’t fully appreciate the idea of validity before age 12 or so. My collaborators and I (Galotti, Komatsu, & Voelz, 1997) followed up on this line of work, looking to see when children recognized the difference between a deductive and an inductive inference. The following two versions illustrate these two types of inference: (1) “All wortoids have three thumbs. Hewzie is a wor- toid. Does Hewzie have three thumbs?” versus (2) “Hewzie is a wortoid. Hewzie has three thumbs. Do all wortoids have three thumbs?” Most adolescents and adults see a distinction between the first problem (which calls for a deductive inference) and the second (which calls for an inductive inference). The former can be made with much greater confidence (in fact, with certainty); the latter, with only some (however strong) degree of probability. Our studies showed that until fourth grade, children did not consistently and clearly articulate the 524 Part V Individual and Situational Differences in Cognition inductive/deductive distinction; however, by about second grade, they showed an implicit understanding of the distinction, answering more quickly and more confidently when asked to draw deductive inferences. This examination of recent work in the non-Piagetian traditions of cognitive development has yielded narrower and more specific descriptions of what actually develops. Typically, instead of focusing on general and widespread cognitive achievements, researchers in these traditions offer accounts that are more specific to the particular tasks being used. Thus an account of how rea- soning ability develops may show little resemblance to an account of how chil- dren acquire and organize new information into concepts. Researchers such as those whose work has been described, however, see this narrowness of scope as positive. By attending to specific tasks and domains, they believe a clearer and more accurate picture will emerge of what children know and can do. Some developmentalists see a large hole left by the demise of grand theo- ries such as Piaget’s (Bjorklund, 1997). They call for us to examine children’s performance on various cognitive tasks in the context of their everyday experi- ences and to look at the evolutionary “advantages” of what may appear to adults to be “failures.” For example, Bjorklund and Green (1992) argued that preschoolers’ unrealistic optimism about their own abilities, frequently taken as an indication of their lack of realistic self-judgment, has some beneficial side effects. Children who think their abilities in some domain are terrific will work longer and harder at practicing their skills in that domain. My son Timmy gave many daily examples when he was a 5-year-old. Convinced his basketball skills were “awesome,” he regularly spent many tireless sessions shooting “hoops,” despite a low success rate. As an adult, my own skills at estimating my basket- ball skill are much better. (Perhaps as a result, I spend as little time as possible practicing my free throws.) SOME POST-PIAGETIAN ANSWERS TO THE QUESTION “WHAT DEVELOPS?” Recall from our discussion earlier that Piagetian theory describes cognitive devel- opment as the acquisition of progressively more sophisticated mental structures. Researchers in other traditions do not necessarily believe that children at differ- ent ages possess qualitatively different mental structures. These researchers instead provide a variety of answers to the question “How do children develop cognitively?” Here we will review some of the most common answers. Neurological Maturation One factor to which cognitive and cognitive developmental psychologists are paying increasing attention is that of neurological, or brain, development.  Chapter 14 Cognitive Development Through Adolescence 525 Although many neurons or nerve cells in the brain emerge during gestation, the brain continues to grow and develop after birth, especially in the first four years (Nowakowski, 1987). Early exposure to stimuli helps to develop a normal level of interconnections among neurons, such that a more complex network of nerve cells is formed. The network allows for the efficient transmission of a great deal of information. Do neurological developments bear directly on cognitive developments? Goldman-Rakic (1987) described research with monkeys suggesting that the age at which infant monkeys can perform certain cognitive tasks (such as a Piagetian object permanence task) coincides with the peak of the development of neuronal connections in an area of the brain known as the prefrontal cortex. Adele Diamond (1991) has extended this line of work, using a classic object permanence task in which an infant, having previously seen an object hidden in location A, watches it hidden in location B, but continues to look for the hid- den object in location A instead of B. Diamond compared older (7–12 months) infants’ ability on the “A, not B” object permanence task to the development of the frontal cortex. This area of the brain has been shown to undergo tremendous growth, both in density of synapses and in myelination of axons. Diamond’s work has shown that improved performance on the “A, not B” task correlates with age (and therefore with frontal-lobe development) in infancy. In her work with monkeys with frontal-lobe lesions, she has produced monkeys with specific neurological deficits who show the same pattern of behavior on the “A, not B” task as do infants of different ages. Diamond (1991) believed that the frontal cortex underlies cognitive perfor- mance both in the ability to integrate information over time and space and in the ability to inhibit strong response tendencies. The infant searching for an object in location A (where it has been previously hidden) instead of in B (where it was just hidden) must keep track of the information that the hiding place has changed and also stop himself from making the same behavioral response (reaching toward A) that was previously successful. More recent work involving brain imaging techniques paints the following picture: With development, the brain becomes more fine-tuned and organized. Brain regions associated with so-called “basic” functions, such as sensation and motor behavior, develop first, in line with Piagetian tenets. Association areas— brain regions that facilitate integration of information—develop a little more slowly. Areas involved in top-down control of behavior, such as the frontal and prefrontal cortex, are the last to develop (Casey, Tottenham, Listen, & Durston, 2005). Moreover, as the individual develops and has certain experiences, certain synaptic connections between neurons in the brain are strengthened, while other, unused ones, are pruned. This pruning results in more efficient neural circuits, but ones that become increasingly specialized and unique to the indi- vidual. Kuhn (2006) speculates that this brain reorganization might account 526 Part V Individual and Situational Differences in Cognition for why, during adolescence, individual differences in performance become more and more common. Although it’s possible to talk about the cognitive abil- ities of a typical 6-month-old, by the time children reach adolescence, there are much wider variations in performance—some adolescents can perform like adults on some tasks, while others cannot. One important factor in this varia- tion, Kuhn believes, stems from the experiences the adolescents engage in, which in turn direct the maintenance or pruning of different neural circuits. The issue of neurological underpinnings of cognitive performance is at the cutting edge of research at the moment. Whether certain cognitive tasks require a certain level of neurological development and the role of environmental expe- rience in neurological functioning and development are matters that will surely be addressed in the coming decade. Working-Memory Capacity and Processing Speed Our review of memory in Chapters 5 and 6 suggested that working memory is an essential ingredient of many cognitive tasks. Recall that working memory is the system in which currently active information is stored and manipulated. It stands to reason, then, that the larger the working-memory capacity, the more complex are the cognitive tasks of which a person is capable. Researchers such as Pascual-Leone (1970) and Gathercole and her colleagues (Gathercole & Pickering, 2000) have tried to measure the amount of “mental space” children seem to have available to perform cognitive tasks. These authors report increases in this capacity with age. Some of the research has involved estimation of memory span, done by giving children lists of items, such as numbers, letters, or words, and asking the chil- dren to repeat them. The memory span is thus the number of items that a child of a particular age can reliably reproduce. Figure 14-5 displays data from sev- eral studies suggesting that memory span increases with age. Some proposals assert that working-memory span is constrained by how quickly information deteriorates from the mental workspace (Hitch, Towse, & Hutton, 2001). Still other researchers have argued that what develops is not working-memory capacity per se but the speed and/or efficiency with which information is processed (Case, 1978; Dempster, 1981). For example, chil- dren at different ages have been shown to differ widely in the speed with which they can name items presented to them, rotate mental images, or search through a visual display (Kail, 1986, 1988). Adults and older children typically perform all these tasks faster than younger children do. Presumably, all these tasks are carried out in working memory. When one task takes longer to carry out than another, it may reflect the expenditure of more “mental effort.” If mental effort is limited, as information-processing theories typically assume, then tasks that require more mental effort will leave fewer cognitive  Chapter 14 Cognitive Development Through Adolescence 527 FIGURE 14-5 Developmental differences in digit span, word span, and letter span. SOURCE: Dempster (1981, pp. 66–68). 10 10 8 8 Word span Digit span 6 6 4 4 2 2 0 0 0 2 4 6 8 10 12 Adult 0 2 4 6 8 10 12 Adult Age Age 10 8 Letter span 6 4 2 0 0 2 4 6 8 10 12 Adult Age resources available for other processing. This in turn could explain the gener- ally poorer cognitive performance of younger children relative to older chil- dren and adults: The younger the processor, the more mental effort is required for a given task. The question of how working-memory capacity and efficiency change with development is still a current research question (see Cowan, Elliott, Saults, Nugent, Bomb, & Hismjatullina, 2006, for a detailed example of research in this area). Attention and Perceptual Encoding Ask any parent or teacher: Younger children have shorter attention spans than older ones. Because of this, they often spend less time exploring the informa- tion available to them from the environment. Preschoolers, in particular, often respond to complex cognitive tasks impulsively—that is, quickly and with many errors (Kogan, 1983). Perhaps related to this, younger children make fewer discriminations between similar objects than do older children (Gibson & Spelke, 1983). 528 Part V Individual and Situational Differences in Cognition You can see a good example of this phenomenon if you look at the comics sections of many Sunday newspapers. Some run a puzzle activity that calls for the child to examine two very similar pictures and to find ten things that dif- fer between them. The two pictures are usually visually complex, with a great number of objects and/or people and a great deal of detail and elaboration of each object. The differences tend to be in the details. For example, one picture might depict a girl with a spotted bow in her hair; another might show the same girl, in the same pose, with the same clothes except for a striped bow. Figure 14-6 gives an example of such a puzzle. Preschoolers and chil- dren in early elementary school typically find these puzzles much more chal- lenging than do older children or adolescents. In part, this has to do with the amount of time they spend looking back and forth between the two pictures. Another part of the explanation, predicted by perceptual learning theory (Gibson, 1969), seems to be that younger children notice fewer differences in the first place. FIGURE 14-6 Find the two pictures that match exactly.  Chapter 14 Cognitive Development Through Adolescence 529 Kemler (1983) has extended this idea, arguing that with development, children shift from a holistic approach to processing information to a more analytic one. By these terms Kemler means that younger children approach information globally and pay attention to the overall similarities between and among objects. For example, given a red triangle, an orange diamond, and a green triangle and asked to “put together the items that belong together,” younger children tend to sort the red triangle and orange diamond together, because overall, these two objects are more similar to each other than either is to the green triangle. In contrast, older children and adults pay attention to particular parts or aspects of information. Given the same sorting task, adults would be likely to classify the red and the green triangles together, because they both share the dimension of shape. Children have also been shown to have difficulty focusing their attention. In one study, Strutt, Anderson, and Well (1975) asked children and adults to sort as quickly as possible a deck of cards showing various geometric figures. Some cards showed figures that differed only in the relevant dimension—for example, only circles and squares when the child was asked to sort on the basis of shape. Other cards included figures that differed on both the relevant dimension and other, irrelevant dimensions—for example, the presence of a line or star either above or below the picture. The presence of irrelevant infor- mation did not affect the speed of sorting for adults. However, it did slow down sorting among 6-, 9-, and 12-year-olds; the younger the child, the greater the interference. This answer to the question “What develops?” implies that younger children approach cognitive tasks differently from older children both perceptually and attentionally. Younger children encode and pay attention to different aspects of information from those aspects older children and adults emphasize. As a consequence, their information processing differs because it begins with different input. The Knowledge Base and Knowledge Structures Some developmental psychologists working in the information-processing tradition regard the acquisition of general knowledge and expertise as a cru- cial aspect of cognitive development. Studies of adults show that people dif- fer in some cognitive processes as a function of level of expertise with the materials used in the task. For example, Chase and Simon (1973) showed a chess master (a certified “expert”), an experienced chess player, and a chess novice different chessboards with the pieces arranged in various ways. The task was to look at a particular board for 5 seconds and then, after the board was removed from view, to reconstruct the placement of the pieces on a sec- ond, empty chessboard. 530 Part V Individual and Situational Differences in Cognition The investigators found that when the first chessboards depicted actual games (that is, the pieces were arranged in ways that might actually occur dur- ing a game), the master and experienced player performed much better than the novice in the number of pieces they could correctly place. However, when the pieces were displayed in random configurations, the chess master per- formed no better than the novice or the experienced player. Chase and Simon (1973) concluded that experts extract more information than do novices when the information being presented is of the type for which their expertise is rele- vant. Said another way, expertise helps a person acquire and organize informa- tion much more efficiently, thus leading to better overall performance when the information pertains to her area of expertise. Notice that this explanation fits well with the findings of Chi with child chess experts, discussed earlier. Chi and Koeske (1983) carried out a related study with a single 41⁄2-year-old fancier of dinosaurs. The investigators first queried the child about his familiarity with and knowledge about different kinds of dinosaurs and then drew up two lists: 20 dinosaurs that the child knew relatively more about and 20 that the child knew relatively less about. On three different occasions, the child was presented with each list, at the rate of 1 dinosaur name every 3 seconds, and was then asked to recall the list. The child recalled significantly more of the “familiar” dinosaurs (about 9 out of 20) than the “unfamiliar” ones (about 4 out of 20). Nancy J. Ashmore Chi’s work suggests that in domains where children have expertise, such as knowledge of toys, children demonstrate better memorial ability.  Chapter 14 Cognitive Development Through Adolescence 531 Chi and Koeske (1983) argued from these and other results that part of the reason why children typically perform so poorly on memory (and presumably other cognitive) tasks may be their relative lack of knowledge or expertise regarding the information used in the tasks. Given the opportunity to perform the same tasks with materials they know well, their performance improves dra- matically. Presumably, familiar materials require less cognitive effort to encode, retrieve relevant information about, notice novel features of, and so on. Other work, by Katherine Nelson and her colleagues, looked in a slightly different way at how children store and organize knowledge, particularly knowledge about events (Nelson, 1986). The primary method here is to ask children to describe their knowledge of familiar routines, such as “What hap- pens when you go to day care?” or “Tell me what happens when you make cook- ies.” In response to the latter request, Nelson and Gruendel (1981) obtained a variety of responses from children of different ages, ranging from “Well, you bake them and eat them” (a 3-year-old) to “First you need a bowl, a bowl, and you need about two eggs and chocolate chips and an egg beater! And then you gotta crack the egg open and put it in a bowl and ya gotta get the chips and mix it together. And put it in a stove for about 5 or 10 minutes, and then you have cookies. Then ya eat them!” (a child of 8 years, 8 months) (p. 135). First, clearly even 3-year-olds have some knowledge of this event. Nelson described the organization of this knowledge in terms of scripts, or generalized event representations (GERs). From Chapter 6, you may remember that scripts contain information organized temporally—that is, by the time in which each thing occurs in an event. Notice how the children use temporal links from one step to another—for example, “First you do X, then Y, and after that you do Z.” One trend that appears with development is that the scripts become longer and more elaborate. Fivush and Slackman (1986) also showed that as children become more familiar with an event (for example, if the event is “going to kindergarten” and children are tested repeatedly as the school year goes on), their scripts also become more complex, specifying more con- ditional information, such as “If it’s raining, we play indoors.” Children’s organization becomes more hierarchical as they specify more options or choices for different activities (for example, “I can play house, or I can draw, or I can read a book, until circle time”). Their organization also becomes more abstract; when describing their script they mention fewer details specific to a certain day’s activity. Nelson (1986) argued that scripts help to support many cognitive activities, including comprehension, memory, and conversation. Scripts and GERs are said to provide the child with a “cognitive context” with which to interpret ac- tions, events, and people in a situation. Especially because younger children appear to perform at their cognitive best only in certain contexts, it is important to learn which aspects of the context help or hinder them. Nelson believed that 532 Part V Individual and Situational Differences in Cognition “the observed difference between situations where children perform well or poorly is that between those for which children have established a relevant GER and those for which they have not” (p. 16). Strategies When confront