topic interest

the Central Issues of Developmental Science Despite great variety in the work they do, developmentalists share an interest in four fundamental issues concerning the process of development: 1. Sources of development. How do the forces of biology, the environment, and the child’s own activities interact to produce new ways of thinking, feeling, and behaving? 2. Plasticity. To what extent and under what conditions is the course of development plastic, that is, malleable and subject to change as the result of either deliberate intervention or chance experience? 3. Continuity/discontinuity. Is development a gradual, continuous process of change, or is it punctuated by periods of rapid change and the sudden emergence of new ways of thinking and behaving? 4. Individual differences. No two human beings are exactly alike. How does a person come to have characteristics that make him or her different from all other people, and how stable are these characteristics over time? Developmentalists’ answers to these questions provide insight into princi­ ples of development, as well as guidelines for promoting adaptive developmental outcomes. Questions about the Sources of Development What drives development? What, for example, ensures that virtually every human infant will develop the ability to walk on two feet? To use words to communicate with others? To form emotional bonds? What part of these processes is written in our genetic code, and what part is determined by our social and cultural en­ vironment? Such questions about the sources of development are often posed as a debate about the relative importance of “nature” and “nurture.” Nature refers to the individual’s inherited biological predispositions. Nurture refers to the influences of the social and cultural environment, particularly the family and the community, and of the individual’s experiences. Much of the argument about Victor, the Wild Boy of Aveyron, was about the relative influences of nature and nurture:WasVictor incapable of speech and other behaviors normal for a boy his age because of a defective biological endowment (nature) or because of his social isolation (nurture)? Modern developmentalists emphasize that development cannot be understood by considering nature and nurture in isolation from each other because the two are so closely intertwined, continually interacting and mutually influencing each other. Nevertheless, as you shall see, debates about the relative importance of ge­ netic inheritance and experience as sources of development continue to preoccupy developmental science. Questions about plasticity The second major question about development concerns plasticity, the degree to which, and the conditions under which, development is open to change and intervention. Plasticity enables individuals to adapt to a wide range of different environments (Causey, Gardiner, & Bjorklund, 2008). An important question for developmentalists concerns the limits of plasticity in children’s responses to different environments and experiences: For different aspects of development, does our ex­ perience influence our development significantly or not much at all?

Early ideas about plasticity were influenced by the identification of certain “critical periods” of development in several nonhuman species.A critical period is a period of growth—in some cases only a few hours long—during which a specific kind of experience must occur for a particular ability or behavior to de­ velop. If the critical period passes without the occurrence of the experience, the developmental “window” closes, and the ability or behavior will not develop. In other words, for the particular aspect of development in question, there is a high degree of plasticity only during this period. For example, in certain species of birds, chicks have a critical period just after hatching during which they become attached to the first moving object they see (usually their mother), which they will thereafter follow wherever it goes (see photo below).This process is called imprinting. If the chicks are prevented from seeing any moving object for a cer­ tain number of hours after hatching so that imprinting does not occur, they fail to become attached to anything at all and may wander around alone. As you can imagine, chicks on their own have little chance for survival (Izawa,Yanagihara, Atsumi, & Matsushima, 2001).

Examples of such “all­or­nothing” critical periods in any species are rare; in our own species they tend to be limited to specific periods of prenatal development. During the ninth week after conception, for example, the presence or absence of certain hormones will determine whether the fetus becomes male or female. Although there is little evidence of “critical” periods in human development after birth, there is abundant evidence pointing to “sensitive” periods (Gottlieb, 2002; Lickliter, 2007). Sensitive periods are defined as times in an organism’s develop­ ment during which a particular experience (or lack of it) has a more pronounced effect on the organism than does exposure to that same experience at another time (Bruer, 2001). For example, children seem to be most sensitive to learning language in the first few years of life, easily acquiring any language to which they are regularly exposed. But even if they are not regularly exposed to language until the age of 6 or 7, it appears that they are still capable of acquiring it. Thereafter, however, the risk of failing to acquire language increases (Newport, Bavelier, & Neville, 2001).

As with sources of development, questions about plasticity have important real­ world implications.The answers are essential to understanding whether and how a child’s development can be modified through deliberate intervention, such as therapy or education, or affected by particular experiences, from the everyday to the traumatic.Questions about continuity/discontinuity have to do with the extent to which development tends to be continuous, consisting of the gradual accumulation of small changes, and the extent to which it is discontinuous, involving a series of abrupt, radical transformations.

As a rule, developmentalists who believe that development is primarily a process of continuous, gradual accumulation of small changes emphasize quantitative change, such as growth in the number of connections among brain cells, in memory capacity, or in vocabulary.Those who view development as a process punctuated by abrupt, discontinuous changes emphasize qualitative change, or new patterns of behavior emerging at specific points in development, such as the change from babbling to talking or from crawling to walking, or from the ability to reason only in terms of one’s own experience to the ability to reason hypothetically. Qualitatively new pat­ terns that emerge during development are referred to as developmental stages.The contrast between the continuity and discontinuity views is illustrated in Figure 1.3.

The psychologist John Flavell (1971) suggests four criteria that are central to the concept of a developmental stage, illustrated below by the transition from crawling to walking.

1. Stages of development are distinguished by qualitative changes. The change in motor activity associated with the transition from crawling to walking upright is qualitative in that walking does not arise from the perfection of the movements used to crawl; instead, it involves a total reorganization of movement, using different muscles in different combinations.2. The transition from one stage to the next is marked by simultaneous changes in a great many, if not all, domains of the child’s development. The transition from crawling to walking is accompanied by a new quality of emotional attachment between children and their caregivers as well as the new forms of child–caregiver relations that the child’s greater mobility requires. Similarly, the transition to biological maturity during puberty takes place in concert with a rising interest in romantic peer relationships and the emergence of more adultlike thinking and reasoning skills.

3. When the change from one state to the next occurs, it is rapid. The transition from crawling to walking typically takes place within the space of about 90 days.

4. The numerous changes across developmental domains form a coherent pattern. Walking occurs at about the same time as pointing, the ability to follow the gaze of another, the child’s first words, and a new relationship between children and their parents.

Supporters of discontinuity and the stage concept argue that the qualitative changes the child undergoes in each new stage alter the way the child experiences the world and the way the world influences the child. For example, before infants have any understanding of language, their learning about the world comes primarily through their actions on it. Once they begin to understand and produce language themselves, the way they learn about the world appears to change fundamentally, and so does the nature of their interaction with others.The discontinuity repre­ sented by the child’s active participation in conversation is so notable that in many societies it marks the boundary between infancy and early childhood.

Supporters of the continuity view maintain that even when development ap­ pears to make an abrupt shift, continuity prevails in the underlying processes. For example, although very young children and adults appear to reason about the world in radically different ways, Tamar Kushnir and Alison Gopnik argue that there is nevertheless considerable continuity in reasoning between early child­ hood and adulthood. In particular, Kushnir and Gopnik believe that, regardless of age, individuals reason much the way scientists do; that is, they have theories that allow them to explain, predict, and understand events and behavior, and they modify their theories when their predictions prove incorrect (Kushnir & Gopnik, 2005).

One major problem for supporters of the stage concept is that, contrary to their depiction of qualitatively consistent, across­the­board shifts in behavior and thinking, children often appear to be in one stage on one occasion and in a dif­ ferent stage on another. According to one influential stage theory of cognitive development, for example, 4­year­olds are in a stage in which their thinking is largely egocentric, making it difficult for them to see anything from a point of view other than their own. Consider 4­year­old Nyia, who wanted to give her mother a Bitty Kitty for her birthday. Nyia’s birthday present choice indicates that she is, in this case, limited to her own perspective: She wants to give her mother what she herself would enjoy as a present, failing to see that her mother might rather have breakfast in bed.Yet when Nyia talks to her 2­year­old brother, she simplifies her speech, apparently taking the younger child’s perspective and real­ izing that he might otherwise have difficulty understanding her.The fact that at a given point in development a child can exhibit behaviors associated with different stages seems to undercut the idea that being in a particular stage defines the child’s capabilities and psychological makeup.Although in some respects you are like all other human beings, in many ways you are psychologically and physically unique, like no one else in the world.What makes you different from everyone else? And will the features that make you different endure throughout your life? When we try to understand the nature of development, we must take into account these two questions about individual differences: (1) What makes individuals different from one another, and (2) to what extent are individual characteristics stable over time?

The question of what makes individuals different from one another is really another form of the question about the plasticity of development (Boyce & Ellis, 2005).The ways in which you are like all other human beings are a reflection of how certain developmental traits—the ability to walk, talk, and form close attach­ ments to others—are highly constrained by evolution and have little plasticity. In contrast, the features that make you unique from everyone else reflect the capacity of certain traits to be more easily modified by experience.

The question of stability over time involves the extent to which the features that make you special endure throughout your life. Parents often remark that their children have been friendly or shy since infancy, but scientifically demonstrating the stability of psychological characteristics like these—at least from an early age—has proved difficult. One problem is that measures that seem appropriate for assessing psychological traits during infancy are not likely to be appropriate for assessing the same traits in an 8­year­old or in a teenager. Perhaps for this reason, many studies have found only moderate stability of individual characteristics in childhood (Caspi, Roberts, & Shiner, 2005). There is evidence that, for example, children who were shy and uncertain at 21 months of age still tend to be so at age 12 or later. Similarly, infants who rapidly processed visual information at 7 months of age still tend to be rapid visual processors at age 11 (Emde & Hewitt, 2001).

The extent of the stability of children’s psychological characteristics over time depends in part on the extent of stability in their environment. Studies have found, for example, that children raised in an orphanage that provides adequate physical care but little emotional and intellectual stimulation tend to be lethargic and low in IQ. But if their environment changes—if they are adopted into caring families in their early years—their condition improves markedly, and many of them become intellectually normal adults (Clarke & Clarke, 2000).

The four major issues of developmental sources,plasticity,continuity/discontinuity, and individual differences have endured for decades and continue to focus the research efforts of developmentalists. In the next section, we explore the major theories that developmentalists have used to help address these issues.“Of course he’s having trouble—his parents work all day and are never home.” “He’s been moody since he hit puberty.”

Now, drawing on your own experience, think of one or more similar phrases for each of the central questions.

theories of Development

Many students roll their eyes at the idea that theories are needed to understand chil­ dren’s development. “What’s so complicated?” they wonder. “Just observe children and let the facts speak for themselves.” But, contrary to popular belief, facts do not speak for themselves. The facts that developmentalists collect add to our under­ standing of development only when they are brought together and interpreted in terms of a theory, a framework of ideas or body of principles that can be used to guide the collection and interpretation of a set of facts.Without the lens of theory through which to observe, we would not know what we were looking at, much less how to characterize it or what to make of it. At the same time, of course, data can be used to test theories, and theories are constantly being revised to better fit the data. In this way, data and theories go hand in hand, each shaping the other.

To appreciate the role of theory, consider a hypothetical example:You are a de­ velopmentalist observing a little boy running around a preschool classroom, hitting the other children and grabbing toys away from them. How would you interpret this instance of misbehavior? If you were framing your explanation with a theory focused on antisocial behavior, you might see the child’s actions as uncontrolled aggression, whereas if you were framing it with a theory focused on the interde­ pendency of group members, you might see those same actions as a symptom of the child’s having failed to develop a sense of his dependency on others for his well­being. (In fact, for cultural reasons, Americans might tend toward the first interpretation, whereas Japanese people might tend toward the second.) Not only would your specific observations be likely to be influenced by the theory you used, but your prescriptions for dealing with the child’s behavior would be as well.

The preceding example also illustrates a point made by Albert Einstein, namely, that theory is present even when we think that we are “objectively observing” the world.We think of our theories as founded on observations, when “[i]n reality the very opposite occurs. It is the theory which decides what we can observe” (quoted in Sameroff, 1983, p. 243).

Einstein’s point underscores the importance of theory. A deeper understand­ ing of human development will not automatically come from the continuous ac­ cumulation of facts. Rather, it will come through new attempts to make sense of this accumulating evidence in the light of relevant theories. It also raises a caution: Developmental scientists, like all scientists, need to keep in mind that their theories can bias, or distort, their observations.Throughout this book, you will see examples of both the power and potential problems of theories.

theory in Developmental Science

There is no single broad theoretical perspective that unifies the entire body of relevant scientific knowledge on human development. Instead, development is approached from several theoretical perspectives that differ in a number of important ways:

1. Domains of development under investigation. A theory may be most appropriate for understanding the ways in which children develop cognitively, socially,emotionally, or physically, or it may explore some combination of these domains. 2. Research methods used. As you will learn in the next section, particular theories are often associated with particular research methods— observational, experimental, and so forth. 3. Central issues addressed. The major theories also differ in their approach to the four central issues we discussed above—the relative contributions of nature and nurture, the degree of plasticity and openness to change, the extent of continuity or discontinuity, and the stability of individual differences. We will begin our discussion of developmental theories by reviewing the “grand theories” that were developed when the field was relatively young.We will then examine several modern theoretical perspectives that the grand theories inspired. Grand theories Most developmentalists would consider four theoretical perspectives to fall into the category of “grand theories”—the psychodynamic, behaviorist, constructivist, and sociocultural perspectives. These perspectives are “grand” not only because they laid the foundation for the modern theories of development that followed them, but also because they are “grand” in scope, each presenting a sweeping view of various domains of development. psychodynamic theories Psychodynamic theories claim a significant place in the history of developmental science, having shown how universal developmen­ tal processes and stages can be understood by exploring the specific life experiences of particular individuals. Sigmund Freud was the first to develop a psychodynamic theory. Over the years, his theory has been adopted and modified by numerous developmentalists, the most prominent of them being Erik Erikson, who, as you will see, combined the primarily biological approach taken by Freud with the view that culture plays a leading role in shaping the path of development. Sigmund Freud. Trained as a neurologist, Freud (1856–1939) sought to create a theory of personality that would enable him to cure the patients who came to him with such symptoms as extreme fears and anxiety, hysteria, and an inability to cope with everyday life. Although many of these symptoms initially appeared similar to those of neurological disorders, Freud believed that they were rooted in unresolved traumatic experiences in early childhood. On the basis of the clinical data he gathered from his patients, including their rec­ ollections of the past and their current dreams, Freud constructed a general theory of psychological development that gave primacy to the ways in which children satisfy their basic biological drives.The theory also gave rise to the method of treat­ ment known as psychoanalysis. Influenced by Darwin’s theory of evolution, Freud reasoned that, whatever their significance for the individual, all biological drives have but a single goal: the survival and propagation of the species. Since reproduc­ tion, the necessary condition for the continuation of the species, is accomplished through sexual intercourse, it followed for Freud that all biological drives must ultimately serve the fundamental sex drive. Freud shocked his contemporaries by arguing that the behavior of children— even infants—is motivated by a need to satisfy the fundamental sex drive. As indicated in Table 1.2, Freud proposed that, beginning in infancy and moving through adolescence and the advent of adult sexuality, the form of sexual gratifi­ cation changes, passing through an orderly series of psychosexual stages related to the parts of the body through which gratification is achieved.According to Freud (1920/1955), each stage is associated with conflicts between the child’s desires and social prohibitions and expectations that militate against the expression of those desires. The way children experience the conflicts at each stage, and whether or not they successfully resolve them, affects their later personality. Freud maintained, for example, that failure to resolve the conflicts of any given stage can result in the individual’s becoming fixated with the issues related to that stage. Perhaps the best­known of such conflicts occurs during the anal stage, when the child is so­ cially required to control elimination. Unresolved conflicts related to overly strict toilet training can, in the Freudian view, lead to an “anal retentive” fixation and a personality marked by emotional rigidity and an extreme need for cleanliness and order.

Another important contribution to understanding development was Freud’s belief that the personality is made up of three mental structures: (1) the primi­ tive id, which is present from birth and consists of biological drives that demand immediate gratification; (2) the ego, which begins to emerge in early childhood and is the rational component of the personality that attempts to mediate a prac­ tical reconciliation between the demands of the id and the contraints imposed on those demands by the outside world; and (3) the superego, which emerges last and, acting as one’s conscience, attempts to suppress the forbidden demands of the id and force the ego to make choices that are morally acceptable (we will return to a discussion of these structures in Chapter 9; see p. 318). According to Freud, these three structures are rarely, if ever, in perfect balance. The constant battle among them is the engine of developmental change, which Freud spoke of as ego development. Central to Freud’s psychodynamic view of development is his idea of the uncon- scious, a storehouse of hidden motives that drive much of the individual’s behavior. These motives, according to Freud, are associated with the unresolved conflicts ex­ perienced during the psychosexual stages of childhood and are kept from conscious awareness because they are threatening. As you will see below, most other major theories pay less attention to the idea of the unconscious, focusing instead on the individual’s conscious behaviors, purposes, and goals. Interestingly, recent advances in neuroscience have rekindled interest in the unconscious, particularly with regard to how unconscious brain processes influence the way individuals think, experience emotions, and make decisions. erik erikson. Whereas Freud’s training was in medicine, Erik Erikson’s (1902–1994) was eclectic, combining his experience in psychoanalysis with a background in art, teaching, and anthropology. Erikson built on many of Freud’s basic ideas of develop­ ment but departed from them in two significant ways. First, Erikson emphasized social and cultural factors, rather than biological drives, as the major force behind develop­ ment. Second, he viewed the developmental process as continuing throughout the life span rather than ending in adolescence (the age of sexual maturity). Erikson believed that the main challenge of life is the quest for identity.Through­ out their lives, people ask themselves “Who am I?” and at each stage of life they arrive at a different answer (Erikson, 1963, 1968b). For Erikson, each psychosocial stage is asso­ ciated with a particular main task, as shown in Table 1.2. Erikson referred to these tasks as “crises” because they are sources of conflict within the person. The person must in some way accomplish the task, or resolve the conflict, in order to move on to the next stage.The resolution may be more on the positive side or more on the negative side—for example, for the first stage, more toward trust or more toward mistrust. A person’s personality and sense of identity are formed in the resolution of these crises. According to Erikson, each individual’s life cycle unfolds in the context of a specific culture. While physical maturation determines the general timetable ac­ cording to which the components of our personality develop, our culture provides us with the contexts in which we must resolve the crises and the tools with which we can resolve them. Behaviorism Behaviorism promotes the basic idea that personal­ ity and behavior are shaped by the individual’s learning experiences. This learning process involves modifying behavior by forming asso­ ciations between observable behavior and its consequences, favorable and unfavorable. In this respect, behaviorism is radically different from psychodynamic theories and their focus on universal biological drives, the development of internal personality structures, and the resolution of inner conflicts. Indeed, according to John B.Watson (1878–1958), behaviorism entirely transformed how human behavior should be un­ derstood and studied because it shifted the focus from the inner work­ ings of the mind and personality to external, observable behaviors and their consequences (Watson, 1930). This shift in focus, according to Watson and other behaviorists, made the science of human behavior and development more “objective” than it had been in the past.An early proponent of behaviorism, Edward Thorndike (1874–1949), captured the general principle of the theory in his law of effect. In essence, the law of effect states that be­ haviors that produce a satisfying effect in a given situation are likely to be repeated in the same or a similar situation, whereas behaviors that produce an uncomfortable effect are less likely to be repeated. Thorndike’s law of effect is readily apparent in efforts to explore how certain experiences such as rewards, punish­ ments, and other reinforcers change the likelihood of a child’s engaging in a particular behavior.According to behaviorism, rewards and punishments gradually shape children to become walkers, talkers, readers, and friends. Indeed, some theorists held the extreme position that development is overwhelm­ ingly the product of learning alone. John B. Watson, for example, was so certain of the primary role of learning in human development, and of the insignificance of other factors, that he boasted that he could use learning principles to train any infant, regardless of talents, abilities, or family history, to become whatever he wished—doctor or lawyer, even beggar­ man or thief (1930, p. 104)! In the view of development as occurring through learning, developmental change is seen as being gradual and continuous. B. F. Skinner, another leading learning theorist, whose theory of operant conditioning is discussed on p. 147, com­ pared development to the creation of a sculpture:The sculptor begins with a lump of clay and gradually shaves away material until the object is complete. In Skinner’s words, “the final product seems to have a special unity or integrity of design, but we cannot find a point at which this suddenly appears” (1953, p. 91). piaget’s Constructivist theory One of the most influential theories in the his­ tory of developmental science is Jean Piaget’s theory of children’s cognitive, or intellectual, development. Piaget (1896–1980) asserted that cognitive development is driven by the interaction of nature and nurture. In this view, nature refers to chil­ dren’s innate motivation to learn and explore, as well as to the maturation of their brain and body. Nurture refers to all the experiences that children learn from.The hallmark of Piaget’s theory is its emphasis on children’s active role in shaping their own cognitive development. He argued in particular that children do not discover the world and the way it works but, rather, actively construct an understanding of the world on the basis of their experiences with it. In Piaget’s constructivist theory, children construct successively higher levels of knowledge by actively striving to master their environments. Piaget believed that children progress through a series of stages of cognitive de­ velopment (see Table 1.3), and he supported this idea through observation of, and interviews and experiments with, children of all ages. Each stage reflects a unique age­related way of understanding or organizing reality. Imagine, for instance, a 6­month­old baby playing with a set of wooden blocks. She may attempt to chew on some and bang them on the floor.The knowledge she constructs about the blocks—that they are better for banging than for chewing—is entirely different from the knowledge she will construct about them when she is 6 years old and can stack them or throw them at her brother.Another example of how children’s stage of cognitive development affects their understanding involves age­related differences in how they tend to explain their parents’ divorce.Younger children who, as noted, have a difficult time understanding the perspectives of others, may believe that they themselves were somehow at fault. Older children, in contrast, have reached a stage of development that allows them to understand the divorce from their parents’ perspective; that is, in terms of their parents’ relationship with each other. As you will learn in later chapters, the ability to detach ourselves from our personal, idiosyncratic points of view in order to understand other perspectives takes place throughout childhood and adolescence and is key to the development of objectivity and advanced forms of reasoning. Indeed, believing that scientific reason­ ing is the pinnacle of cognitive development, Piaget devoted much of his work to understanding how less mature forms of objectivity and reasoning are transformed over time to become more scientific. On the basis of data from various cultures, Piaget (1966/1974) be­ lieved that development can be speeded up or slowed down by varia­ tions in the environment (such as the presence or absence of formal schooling) but that all children go through the same basic stages. In this important sense, a constructivist approach assumes that the processes of developmental change are universal, the same in all human groups. In Piaget’s view, the most basic unit of cognitive functioning is the schema, a general framework that provides a model for understanding some aspect of the world (Piaget & Inhelder, 1969). Over time, as children interact with their environment, they change—strengthen or transform—their schemas through adaptation to new information, which involves processes Piaget termed assimilation and accommodation. In assimilation, individuals incorporate new experiences into their existing schemas, strengthening those schemas. For example, in Piag­ et’s view, infants have a primitive schema of sucking that enables them to draw milk from a nipple. However, sucking does not remain strictly bound to milk­yielding nipples. Soon, babies are likely to find, say, a pacifier, instead of a nipple, touching their lips, and to start sucking on the pacifier—and in much the same way, since a pacifier is designed to be similar to a

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