Chapter 8. Developmental Psychology

The concept of development is the backbone of modern behavioral science. Psychiatric practitioners and behavioral scientists are concerned primarily with change, its origins, and its control. Developmental psychology is the scientific study of the structure, function, and processes of systematic growth and change across the life span. Systems of classification of behavior (including psychiatric nosology) take into account not only contemporaneous features and formal similarities among current symptoms and syndromes but also past qualities, immediate consequences, long-term outcome and likelihood of change (naturally or through treatment).

Whereas developmental psychology is concerned with species-typical patterns of systematic change (and central tendencies of the species), the discipline of developmental psychopathology is concerned with individual differences and contributes greatly to the understanding of childhood disorders.

The organizing framework of developmental psychopathology is a movement toward understanding the predictors, causes, processes, courses, sequelae, and environmental symbiosis of psychiatric illnesses in order to discover effective treatment and prevention. This movement is guided by in a developmental framework that integrates knowledge from multiple disciplines (e.g., psychobiology, neuroscience, cognitive psychology, social psychology) and levels of analysis (e.g., neuronal synapse, psychophysiologic response, mental representation, motor behavior, personality pattern). The relationship between developmental psychology and developmental psychopathology is reciprocal: The study of normal development gives context to the analysis of aberrations, and the study of psychopathology informs our understanding of normative development.

A developmental orientation forces a scholar to ask questions that move beyond the prevalence and incidence of disorders. Table 8–1 lists some of these questions.

The Orthogenetic Principle

The orthogenetic principle proposes that development moves from undifferentiated and diffuse toward greater complexity, achieved through both differentiation and consolidation within and across subsystems. The newborn infant is relatively undifferentiated in response patterns, but through development achieves greater differentiation (and less stereotypy) of functioning. Each period of development is characterized by adaptational challenges resulting from environmental demands (e.g., a mother who has become unwilling to breast-feed) and from emerging internal influences across subsystems (e.g., growing recognition of the self as able to exert control). The challenges are best conceptualized not as mere threats to homeostasis; rather, change and the demand for adaptation define the human species, and challenges push the individual toward development. The inherent adaptational response of the species is toward mastery of new demands. The mastery motive is as yet unexplained by science, although it is characteristic of the human species (see “Adaptation and Competence” section later in this chapter).

Thus, development is characterized by periods of disruption in the homeostasis of the organism brought on by new challenges, followed by adaptation and consolidation until the next challenge is presented. The adaptive child uses both internal and external resources to meet a challenge. Successful adaptation is defined as the optimal organization of behavioral and biological systems within the context of current challenges. Adaptation requires the assimilation of past organizational structures to current demands as well as the generation of new structures equipped to meet the demands.

Piaget described two types of change: assimilation, which involves incorporation of the challenge into existing organizational structures (e.g., an infant might treat all adults as the same kind of stimulus); and accommodation, which involves reorganization of the organism's structures to meet the demands of the environment (e.g., a developing infant learns to discriminate among adults and to respond differently to different adults) (see “Organismic Theory” section later in this chapter). Accommodation is more complex than assimilation, but successful adaptation requires a balance of both.

Maladaptation, or incompetence in responding to challenge, is characterized by the inadequate resolution of developmental challenges (as in the psychoanalytic concept of fixation). Maladaptation may be evidenced by developmental delays or lags, such as the continuing temper tantrums of an emotionally dysregulated child beyond the period when such behavior is normative. At any phase, the organism will manifest some form of regulation and functioning, even if it is not advantageous for future development. Thus, the child's tantrums might serve to regulate both a complex external environment of marital turmoil and an internal environment of stress. However, suboptimal regulation will prevent or hamper the individual from coping with the next developmental challenge.

Sometimes, apparently effective responses to a particular challenge lead to maladaptation at a more general level. Consider a toddler who responds to the withdrawal of a mother's undivided attention by ignoring her. Although this pattern of response may mean calmer evenings temporarily, the toddler will be ill equipped to respond to other challenges later in development. Consistent social withdrawal may cause the child to fail to acquire skills of assertion; however, continued ignoring of the mother may lead to a phenotypically distinct response in the future (e.g., depression in adolescence). Thus, the orthogenetic principle calls to mind the functioning of the’ entire organism (not merely distinct and unrelated subsystems) and the readiness of that organism to respond to future challenges.

Major Principles of Ontogeny & Phylogeny

Cairns and Cairns outlined seven principles that characterize the human organism in interaction with the environment over time: conservation, coherence, bidirectionality, reciprocal influence, novelty, within-individual variation, and dynamic systems. The first principle is that of conservation, or connectivity in functioning across time. Even with all the pressure to change, social and cognitive organization tends to be continuous and conservative. The constraints on the organism and the multiple determinants of behavior lead to gradual transition rather than abrupt mutation. Observers can recognize the continuity in persons across even long periods of time; that is, we know that a person remains the same “person.” For Piaget, who began his career by writing scientific papers on the evolution of mollusks, this within-person continuity principle is consistent with his view that species-wide evolution is gradual. Piaget believed that development within individuals reflects development of the species (i.e., ontogeny recapitulates phylogeny).

The second principle is coherence. Individuals function as holistic and integrated units, in spite of the multiple systems that contribute to any set of behaviors. One cannot divorce one system from another because the two systems function as a whole that is greater than its component parts. This fact is another conservative force, because an adverse effect on one part of a system tends to be offset by compensatory responses from other parts of the system. This phenomenon applies to all human biological systems and can be applied to psychological functioning.

The third principle is a corollary of the second: Influence between the organism and the environment is bidirectional. The person is an active agent in continuous interaction with others. Reciprocal influences are not identical; rather, at each stage of development, the person organizes the outer world through a mental representational system that mediates all experience with the world. Nevertheless, reciprocity and synchrony constrain the person, and the relative weight of these constraints varies at different points in development. At one extreme, it is possible to speak of symbiosis and total dependency of the infant on the mother; at the other extreme, behavior geneticists refer to genetic effects on environmental variables (such as the proposition that genes produce behavior that leads to the reactions that one receives from others in social exchanges).

Another corollary of the second principle is the principle of reciprocal influence between subsystems within the individual. Behavioral, cognitive, emotional, neurochemical, hormonal, and morphologic factors affect each other reciprocally. Mental events have biological implications and vice versa. Among the most exciting research directions in developmental psychopathology has been afforded by the technology of functions magnetic resonance imaging (fMRI), which enables the understanding of how environmental stimuli and behavioral displays are mediated through brain activity.

The fifth principle of ontogeny is that novelty arises in development. Change is not haphazard. The forces of reciprocal interaction within the individual and the environment lead not only to quantitative changes in the individual but also to the emergence of qualitatively distinct forms, such as locomotion, language, and thought. These changes represent growth rather than random events, in that previous forms typically remain and are supplemented by novel forms.

The sixth principle of phylogeny is that of within-individual variation in developmental rates across subsystems. Change within a subsystem occurs nonlinearly, as in language development or even physical growth. Some of this nonlinearity can be explained by species-wide phenomena, such as puberty, but much of it varies across individuals. In addition, rates of change vary within an individual across subsystems. Consider two young children, identical in age. Child A may learn to crawl before child B, but child B might catch up and learn to walk before child A. Likewise, child B might utter a recognizable word before child A, but child A might be talking in sentences before child B. This unevenness within and across individuals characterizes development and makes predictions probabilistic rather than certain. Some of the variation is attributable to environmental factors that have enduring personal effects (such as the lasting effects on cognitive achievement of early entry into formal schooling) or biological factors that have enduring psychological effects (such as the effect of early puberty on social outcomes), whereas other factors may have only temporary effect (such as efforts to accelerate locomotion onset) or no effect at all.

Finally, according to the seventh principle, development is extremely sensitive to unique configurations of influence, such as in dynamic systems. Growth and change cannot be reduced to a quantitative cumulation of biological and environmental units. Also, development is not simply hierarchical, with gradual building of functions on previous ones. Rather, development often follows a sequence of organization, disorganization, and then reorganization in a different (possibly more advanced) form. In physical sciences, this principle is called catastrophe theory, reflecting the hypothesis that during the disorganization, events are literally random. But reorganization occurs eventually, in lawful and predictable ways.

Dynamic systems theory incorporates several postulates about growth and change. First, change occurs nonlinearly. Second, minor quantitative changes can lead to dramatic qualitative changes in state. Consider how flow of water from a spigot changes from a succession of droplets to a stream or how water itself turns to ice. These major qualitative shifts occur in a regulated way with only minor qualitative changes in a parameter. Third, microlevel events that occur repeatedly often precipitate macrolevel changes in an organism's state.

Granic and Patterson (2006) have described how dynamic systems theory contributes to our understanding of the development of serious conduct disorder. Early difficult temperament and minor conduct problems sometimes shift dramatically to serious violence and antisocial personality disorder through a series of subtle changes in the microlevel characteristics of a parent–child relationship. Coercive exchanges, positive reinforcement, and capitulation by one party at a microlevel can lead a child to emerge from the interaction with macrolevel changes in the propensity for antisocial behavior in other relationships.

Age Norms

A simple but powerful developmental concept that has affected psychiatric nosology is that of age norms. Rather than evaluating a set of behaviors or symptoms according to a theoretical, absolute, or population-wide distribution, diagnosticians increasingly use age norms to evaluate psychiatric problems. Consider the evaluation of temper tantrums. In a 2-year-old child, tantrums are normative, whereas in an adult, angry outbursts could indicate an intermittent explosive disorder or antisocial personality. More subtle examples affect the diagnosis of many disorders in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), such as attention-deficit/hyperactivity disorder, mental retardation, and conduct disorder. With regard to major depressive episodes and dysthymic disorder, age-norming has resulted in consideration of different symptoms at different ages in order to diagnose the same disorder (e.g., irritability and somatization are common in prepubescent depression, whereas delusions are more common in adulthood). DSM-IV explicitly requires consideration of age, gender, and culture features in all disorders, suggesting the importance of evaluating symptoms within the context of their expression.

The importance of age-norming suggests the need for empirical studies of symptoms in large epidemiologic samples and the linking of research on normative development to psychopathology. In this way, developmental psychopathology is similar to psychiatric epidemiology (see Chapter 5). Despite the increased emphasis on age-norming, ambiguity pervades current practice. DSM-IV defines disorders in terms of symptoms that are quantified as “often,” “recurrent,” and “persistent” without operational definition. Some clinicians intuitively contextualize their use of the term “often” relative to a child's agemates (so that “often displays temper tantrums” might mean hourly for a 2-year-old child and weekly for a teenager), whereas other clinicians do not (so that “often” has the same literal meaning across all ages). The “specific meaning of these terms is not clear in the context of some DSM-IV disorders. Complete age-norming might imply the removal of all age differences in prevalence rates (reducing disorder merely to the statistical extremes of a distribution at an age level), whereas complete neglect of age norms implies that at certain ages a disorder is ubiquitous. To resolve these problems, developmental researchers need to learn which patterns of symptoms ought to be examined epidemiologically, and psychopathologists need to compare their observations to empirical norms.

Developmental Trajectories

Diagnosticians must consider not only the age-normed profile of symptoms but also the developmental trajectories of those symptoms (both age-normed and individual). For example, consider three 10-year-old children who exhibit aggressive behavior. As depicted in Figure 8–1, child A has displayed a relatively high rate of aggression historically, but the trajectory is downward. Child B has displayed a constant rate of aggressive displays, and child C's aggressive displays have accelerated geometrically. Which child has a problematic profile? The diagnostician will undoubtedly want to consider not only current symptom counts (in relation to age norms) but also the developmental trajectory of these counts (and the age norm for the trajectory). Child C might be most problematic because of the age trend, unless this trend were also age normative (e.g., some increase in delinquent behavior in adolescence is certainly normative). In contrast, child B's constant pattern might be problematic if the age-normed trend were a declining slope.

Some DSM-IV disorders explicitly take into account the trajectory of an individual's symptoms. For example, Rett's disorder, childhood disintegrative disorder, and dementia of the Alzheimer's type involve deviant trajectories. The diagnosis of other disorders may require trajectory information that is not yet available. This information must be based on longitudinal study of individuals and not cross-sectional data, because only longitudinal inquiry allows for the charting of growth curves within individuals over time. Population means at various ages indicate little about within-individual changes. Population-wide symptom counts might grow systematically across age even when individual trajectories are highly variable.

Recent advances in quantitative methodology have enabled researchers to identify trajectories of development that mark different risk. Growth curve analyses are being used to identify predictors of trajectories so that dimensions can forecast future change in behavior based on normative profiles.

The Boundary between Normal & Abnormal

One of the tenets of developmental psychology is that a knowledge of normal development informs psychopathology partly because the boundaries between normal and abnormal are sometimes vague, diffuse, or continuous. Many disorders (e.g., conduct disorder, dysthymic disorder) are defined on the basis of cutoffs in dimensional criteria rather than on qualitative distinctions that are more easily recognizable. Criteria such as “low energy” and “low self-esteem” (for dysthymic disorder) and “marked or persistent fear” (for social phobia) are matters of degree. One of the central questions is where to locate the boundary between normal and abnormal when the criteria of psychopathology are dimensional.

In some cases, the boundary is arbitrary. In other cases the “true” boundary might be identified on the basis of three considerations: (1) a noncontinuous pattern of the distribution of scores, (2) a qualitatively distinct change in functioning that accompanies a quantitative difference in a score, or (3) unique etiology at the extreme of a distribution.

The first consideration is whether the population of scores is distributed normally with a single mode or bimodally with an unusually large number of cases at one extreme. A large number of cases at one extreme would suggest that a second causal agent is operating, beyond whatever agent caused the normal distribution. A second causal agent might suggest a deviant (i.e., psychopathologic) process. Consider the relation between the intelligence quotient (IQ) score (a continuous measure) and mental retardation. The distribution of IQ scores in the U.S. population is not normal. Far more cases of IQs below 70 occur than would be expected by a normal distribution. Thus, the distinction between normal and abnormal IQ scores is not merely one of degree.

The second consideration is whether qualitative differences in functioning occur with quantitative shifts in a criterion. For example, if a decrement of 10 IQ points from 75 to 65 makes it significantly more difficult for a child to function in a classroom than a decrement from 100 to 90, then a case can be made for locating the cutoff point near an IQ of 70.

The third consideration is the possible distinct etiology of scores at an extreme end of the distribution. A single set of causes will ordinarily lead to a normal distribution of scores. A disproportionate number of scores at an extreme often suggests a separate etiology for those scores. In the case of IQ scores, one set of forces (e.g., genes, socialization) leads to a normal distribution, whereas a second set of forces (e.g., Down syndrome, anoxia, lead toxicity) leads to a large number of cases at the low extreme.

Multiple Pathways

A vexing problem highlighted by research in developmental psychology is that some disorders involve multiple etiologic pathways. The principles of equifinality and multifinality, derived from general systems theory, hold for many disorders. Equifinality is the concept that the same phenomenon may result from several different pathogens. For example, infantile autism results from congenital rubella, inherited metabolic disorder, or other factors. Multifinality is the concept that one etiologic factor can lead to any of several psychopathologic outcomes, depending on the person and context. Early physical abuse might lead to conduct disorder or to dysthymic disorder, depending on the person's predilections and the environmental supports for various symptoms; poverty predisposes one toward conduct disorder but also substance abuse disorder.

The diversity in processes and outcomes for disorders makes the systematic study of a single disorder difficult. Unless scholars consider multiple disorders and multiple factors simultaneously, they cannot be sure whether an apparent etiologic factor is specific to that disorder. Inquiry into one disorder benefits from a conceptualization within a larger body of development of normal adjustment versus problem outcomes. The broad coverage of developmental psychology provides the grounding for inquiry into various disorders.

Biosocial Interactions

The discovery of biosocial interactions in psychiatric disorders has been labeled one of the most important discoveries on all of science in the past decade. Not only are multiple distinct factors implicated in the genesis of a disorder, the profile of factors often conspires to lead to psychopathologic outcomes. Empirically, this profile is the statistical interaction between factors (in contrast with the main effects of factors). Thus, a causal factor might operate only when it occurs in concert with another factor. For example, the experience of parental rejection early in life is a contributing factor in the development of conduct disorder but only among that subgroup of children who also display a biologically based problem such as health difficulties at the time of birth. Likewise, health problems at birth do not inevitably lead to conduct disorder; the interaction of a biologically based predisposition with a psychosocial stressor is often required for a psychopathologic outcome.

Caspi et al. (2002) hypothesized that risk for conduct disorder grows out of the early experience of physical maltreatment, but only among a subpopulation characterized by polymorphism in the gene encoding the neurotransmitter-metabolizing enzyme monoamine oxidase A (MAOA). They found that physically maltreated children with a genotype conferring high levels of MAOA expression were less likely to develop antisocial problems than children without this genotype. These findings help us understand why not all victims of maltreatment grow up to victimize others, and they also indicate that environmental experiences may be necessary to potentiate the action of a genotype.

The same group of researchers has discovered a biosocial interaction in the development of depressive disorder. Life stressors precipitate the onset of depressive episodes, but only among a subpopulation characterized by a functional polymorphism in the promoter region of the serotonin transporter (5-HT T) gene. Individuals with one or two copies of the short allele of the 5-HT T promoter polymorphism exhibit more depressive symptoms, diagnosable depression, and suicidality in response to stressful life events than individuals homozygous for the long allele. The importance of biosocial interactions suggests the importance of examining multiple diverse factors simultaneously, both in empirical research and clinical practice.

Critical Periods & Transition Points

A critical period is a point in the life span at which an individual is acutely sensitive to the effects of an external stimulus, including a pathogen. Freud argued that the first 3 years of life represent a critical period for the development of psychopathology, through concepts such as regression, fixation, and irreversibility. The concept of critical stages gained credence with studies of social behavior in animals by the ethologist Lorenz and the zoologist Scott. This concept is part of several central theories of social development, such as Bowlby's attachment theory (discussed later in this chapter). The rapid development of the nervous system in the first several years, coupled with relatively less neural plasticity in subsequent years, renders this period critical. The effects of exposure to lead and alcohol, for example, are far more dramatic when the exposure occurs in utero or in early life.

A variation of the concept of a critical period is the hypothesis of gradually decreasing plasticity in functioning across the life span. As neural pathways become canalized, mental representations become more automatic and habits form. However, the notion of the primacy of early childhood has been thrown into question by empirical data that indicate greater malleability in functioning than was previously thought. Rutter, for example, suggests that a positive relationship with a parental figure is crucial to the prevention of conduct disorder and that this relationship can develop or occur at any point up to adolescence, not just during the first year of life.

Some developmental psychologists have argued for other critical periods in life, such as puberty and giving birth as critical periods for the development of major depressive disorder in women, although this assertion has been contested. Critical periods might be defined not only by biological events but also by psychosocial transitions. Developmental psychologists have increasingly recognized the crucial role of major life transitions in altering developmental course, accelerating or decelerating psychopathologic development, and representing high-risk periods for psychopathology. These transition points include but are not limited to entry to formal schooling, puberty and the transition to junior high school, high school graduation and entry into the world of employment, marriage, birth of children, and death of loved ones (particularly parents or spouse). These transitions have been associated with elevated risk for some forms of psychopathology. One task of developmental psychologists is to discover which life transitions are most crucial and how these transitions alter the course of development of some but not other forms of psychopathology.

Importance of Context

One of the most important contributions of developmental psychology has been the discovery that patterns of behavior, and of process–behavior linkage, vary across contexts. In the context of U.S. society, a child who is teased by peers might find support for retaliating aggressively, whereas the same teasing experience in Japanese society might cause shame, embarrassment, and withdrawal. Thus, reactive aggressive behavior might be stigmatized as psychopathology in one culture but not another. Context shapes single behaviors and may also shape patterns of psychopathology.

Context also provides the frame or ground through which individual behaviors are given meaning. For example, a child interprets a parent's discipline in relation to norms that are observed culture-wide. In cultures that endorse the use of corporal punishment as appropriate, a child who is punished in this manner (at mild, nonabusive levels) is not at particularly high risk for anxiety problems or conduct problems. However, in cultures that do not endorse this type of parenting, a child who is corporally punished is likely to interpret it as a signal that the parent rejects the child as aberrant or is an aberrant parent, and either interpretation is likely to lead to anxiety and conduct problems.

Context can be defined at many levels, from discrete situational features to broad cultural features and from internal states such as mood to external factors such as geography or time of day. Bronfenbrenner's continuum of environmental contexts forms the basis of his ecological theory (discussed later in this chapter).

Adaptation & Competence

Research in developmental psychology has sometimes enabled sharper distinctions between normal and abnormal (such as when a genetic marker of a disorder is identified), but more often it has articulated the continuity between normal and abnormal. Research has suggested that disorders might be defined less by noncontextualized behavioral criteria (e.g., a score on an IQ test) and more by an assessment of the individual's level of adaptation and functioning. This concept has been embraced by the term competence, or adaptive functioning, which is the level of performance by an individual in meeting the demands of his or her environment to the degree that would be expected given the environment and the individual's age, background, and biological potentials.

Empirical research has shown that measures of childhood social competence are important predictors of adolescent psychiatric disorders, including conduct disorder and mood disorders. Impaired social competence is a premorbid marker for the onset of schizophrenia and is a predictor of relapse.

The concurrent importance of adaptive functioning is so obvious that this concept has become part of the diagnostic criteria for some disorders. For example, a diagnosis of mental retardation requires impairment in adaptive functioning above and beyond the score on an IQ test. A diagnosis of generalized anxiety disorder requires impairment in social functioning in addition to the absolute pattern of anxiety. A diagnosis of obsessive–compulsive disorder requires marked personal distress or significant impairment in functioning. Some broad definitions of mental disorder are based on a general assessment of an impairment in adaptive functioning due to cognitive or emotional disturbance.

Risk Factors & Vulnerability

Epidemiologic and developmental researchers have introduced the notion of risk factors to identify variables known to predict later disorder (see Chapter 5). A risk factor is defined by its probabilistic relation to an outcome variable, without implying determinism, early onset of disorder, or inevitability of outcome. Risk factors are either markers of some other causal process or causal factors themselves. One goal of developmental research is to determine the causal status of risk markers. As noted earlier in this chapter, social competence, or level of adaptive functioning, is a broad risk factor for many disorders, but empirical research must determine whether this factor merely indicates risk that is caused by some other factor (e.g., genes) or constitutes a contributing factor in itself.

Risk factors often accumulate in enhancing the likelihood of eventual disorder. For example, the probability of conduct disorder is enhanced by low socioeconomic status, harsh parenting, parental criminality, marital conflict, family size, and academic failure. The number of factors present seems to be a stronger predictor of later disorder than is the presence of any single factor, suggesting that causal processes are heterogeneous and that risk factors cumulatively increase vulnerability to a causal process.

The concept of vulnerability has been applied to individuals who are characterized by a risk factor. Many empirical studies of the development of disorder use samples that are defined by a risk factor (such as offspring of alcoholics and first-time juvenile offenders); however, it is not clear that the causal and developmental factors are similar in disordered individuals who come from high-risk and low-risk populations.

Mediators & Process

Developmental psychologists study the causal process through which disorder develops. The identification of a risk factor does not necessarily imply a causal process for these reasons: (1) a risk factor might be a proxy for a causal factor and empirically related to a disorder only because of its correlation with this causal factor (the so-called third-variable problem), (2) a risk factor might occur as an outcome of a process that is related to a disorder rather than as the antecedent of the disorder, or (3) a risk factor might play a causal role in a more complex, multivariate process. Indeed, individuals who are predisposed to a disorder often select environments that are congruent with the disorder. The environment might appear to “cause” the disorder but instead merely be a marker of risk. Therefore, developmental psychologists often attempt to understand the process through which risk factors are related to eventual disorder. The factors that are identified as intervening variables in this process are called mediators, or variables that account for (or partially account for) the statistical relation between a risk factor and a disorder.

Four empirical steps are required to demonstrate at least partial mediation (Figure 8–2). First, risk factor A must be empirically related to outcome C (i.e., there must be a phenomenon to be mediated, called the total effect). Second, A must be related to mediator B. Third, B must be related to C. Finally, in a stepwise regression or structural equation model analysis, when B has been added to the prediction of C, the resulting relation between A and C (called the direct effect) must be reduced significantly from the original bivariate relation. The difference between the total effect and the direct effect is called the indirect effect, that is, the magnitude of the mediation of the effect of A on C by B.

An example (depicted in Figure 8–2) is the biased pattern of social information-processing that often results from an early history of physical abuse. Early abuse (A) is a known risk factor for the development of conduct disorder (C) (i.e., it is statistically correlated with later conduct disorder, but many abused children do not develop this disorder nor do all persons who have conduct disorder show a history of abuse). Early abuse is also correlated with the development of a social information-processing pattern (B) of hypervigilance to threatening cues, perceiving the social world as a hostile and threatening place, and poor social problem-solving skills. These mental factors (B) are associated statistically with later conduct disorder (C) and account for about half of the effect of early abuse (A) on later conduct disorder (C).

Moderators & Protective Factors

Rutter found that the effect of a risk factor on a disorder can vary across contexts, populations, or circumstances. That is, the magnitude of an effect might be reduced (or enhanced) under different conditions. For example, the effect of early harsh discipline on the development of conduct disorder is reduced under circumstances of a warm parent–child relationship. This phenomenon is called a moderator effect and is defined by a significant interaction effect between a risk factor and a moderating factor in the prediction of a disorder.

Moderator variables have also been called protective, or buffering, factors. A protective factor protects, or buffers, the individual from the pathogenic effects of a risk factor. Intelligence and a positive relationship with a caring adult have been the most commonly studied protective factors for a variety of disorders. One remaining question is whether protective factors operate more strongly in high-risk than in low-risk groups; that is, if a variable buffers both low-risk and high-risk groups from risk, it is not clear whether that variable would be defined as a protective factor (or simply another predictor variable).

Intervention & Prevention as Experiments

There is a reciprocal relation between the scientific study of behavior in developmental psychology and the application of scientific principles to psychiatry. Concepts from developmental psychology have been applied in psychiatric practice, but psychiatric intervention can also be viewed as a field experiment to test hypotheses about behavioral development. Systematic intervention and prevention can be viewed as experiments to test basic principles. In fact, given the complexity of human behavioral development and the ethical restraints against known iatrogenic manipulations, clinical practice may be the most powerful scientific tool available to test hypotheses from developmental psychology. Thus, the relation between these disciplines is reciprocal, and communication between the disciplines must be preserved.

Seven major theories of development are listed in Table 8–2, along with key concepts and criticisms of each theory. These theories, along with their applications, are described in detail in the sections that follow.

Temperament Theory

Since the “human bile” theories of ancient Greeks, scholars have speculated that persons are born into the world with varying predispositions to behave in particular ways, called traits. Trait theorists have postulated a variety of dispositional tendencies, from Eysenck's neuroticism and extraversion to the “Big Five” traits of agreeableness, openness, extraversion, neuroticism, and conscientiousness. In developmental inquiry, temperament theory has received the greatest attention. It has been hypothesized that infants are born with biologically based temperaments that vary on a continuum from difficult to easy. This trait is evidenced in ease of early care, including feeding, soothing, and cuddling. As children grow older, these differences are evidenced in ease of manageability (e.g., the temper tantrums of 18-month-old children and the behavior difficulties of the preschool period). The trait of difficultness has been hypothesized as a risk factor for conduct disorder. Empirical studies have found significant but modest support for this hypothesis. Prospective studies indicate that infants characterized as difficult are indeed at risk for conduct problems in the early school years, but the relation is somewhat weaker (although still present) for predictions from infancy to adolescence.

A different temperament theory, proposed by Kagan, has focused on the continuum of biological inhibition as the marker variable. Some infants regularly withdraw from novel social stimuli (inhibited pattern) whereas others seek out social stimulation (uninhibited pattern). Optimal levels of inhibition may fall between these extremes. Highly inhibited infants exhibit separation anxiety from parents and are likely to grow into shy, fearful, and withdrawn children. They are thought to be at risk for panic disorder in adulthood. Inhibited individuals demonstrate an increase in heart rate and stabilization of heart rate variability in response to a stress challenge. Individuals vary systematically in the degree to which the hypothalamus, pituitary gland, and adrenal gland (called the HPA axis) respond with glucocorticoid secretion during stress. Inhibited children have a lower threshold of sympathetic nervous system response and display a greater rise and stabilization of heart rate than uninhibited children exhibit. This pattern acts as a traitlike temperamental characteristic throughout life that may be associated with symptoms of anxiety.

Another postulate of temperament theories is that temperament elicits environmental treatment that perpetuates behavior consistent with that temperament. For example, it is hypothesized that “difficult” children elicit harsh discipline, which exacerbates difficult behavior, whereas inhibited children seek secure environments that pose minimal challenge and risk. Plomin has shown through twin and adoption studies that environmental experiences have a heritable component; that is, inherited genes lead either to behavior patterns that elicit environmental reactions or to behaviors that seek particular environments, a phenomenon known as niche-picking.

Applications of the Theory

Most temperament theorists recognize the importance of both inherited and environmental sources of development, so this theory has spawned empirical research directed toward understanding how these forces interact. It may be that infants with a particular temperament will develop more favorably under certain environmental conditions than others, and the task of inquiry is to identify optimal temperament-environment matches. Researchers are examining whether temperamentally difficult (or highly inhibited) infants develop more favorably under conditions of environmental restraint and structure or flexibility and freedom.

Another application has been to encourage research on the process through which genetic effects may operate on human development, thus informing the age-old debate between the influence of nature and nurture on human behavior (see Chapter 6).

Criticisms of the Theory

One problem with research on temperament theory has been the reliance on parents for assessments of temperament. Parents may be biased or inaccurate, or they may lack a broad base of knowledge of other infants. A parent's perceptions about his or her child may be legitimate factors in the child's development, but these perceptions confound information about the child's actual behavior with the parent's construal of the behavior. Direct observational measures of behavior have been developed to assess temperament, as have measures of biological functions, including heart rate reactivity, cortisol secretions, and skin conductivity. These measures also show some stability across time and some predictive power, but the number of studies is small and the statistical effects weak.

Another problem is the difficulty of distinguishing genetic–biological features from reactions to environmental treatment. A 6-month-old infant brings both a genetic heritage and a history of environmental experiences to current interactions. Even biological measures (e.g., resting heart rate, cortisol levels) have a partial basis in past social exchanges, so that the task of sorting genetic from environmental sources in biobehavioral measures is difficult.

Organismic Theory

No one has had more influence in developmental psychology than Piaget. The coherence of behavior across diverse domains and the tendency for changes in abilities to occur simultaneously across domains form the basis of the organismic theory of Piaget and others such as Gesell, Werner, and Baldwin. This theory attempts to describe general features of human cognition and the systematic changes in thought across development. The organizing principle in organismic theory is structure, which is a closed system of transformational rules that govern thought at a particular point in development. Consider the 5-year-old girl who observes one row of nine beads placed near each other and a second row of six beads stretched across a greater distance than the first row. Even though the girl has counted the beads in each row and knows that nine is greater than six, in response to the question, “Which row has more beads?” she will answer, “The row with six beads.” Moreover, the girl will see no contradiction in her answer. According to Piaget, this nonobvious phenomenon occurs because the girl's structural transformation law is to consider the whole of a stimulus, not each part separately. The child's rule structure is closed; that is, it is internally consistent and not easily altered by external contradictions.

Piaget hypothesized that infants are born with a general wiring for a crude set of transformational rules common to all sensorimotor coordination. These rules are part of the evolutionary inheritance of the human organism. Development occurs over a 12- to l5-year period in nonlinear chunks, called stages. Within each stage, functioning is internally consistent and stable (called an equilibrium). Change from one stage to the next occurs as a result of interaction between the child and the realities of the environment. When contradictory realities accumulate sufficiently, change occurs rapidly and globally. As discussed earlier in this chapter, processes of change involve assimilation and accommodation. Assimilation is the act of interpreting environmental experiences in terms that are consistent with existing rule structure (a form of generalization), whereas accommodation is the act of altering rule structures to account for environmental experience (a form of exception noting). Children engage in both assimilation and accommodation in order to maintain coherence (and the perception of consistency), until their overgeneralizations and exceptions become so contradictory that they must create higher-level, more flexible, novel structures that account for the contradictions of earlier stages. When a novel structure (i.e., a new set of rules) is achieved, equilibration consolidates the rules until contradictions accumulate to set the scene for the next stage change. Piaget's four broad stages of cognitive development are (1) the sensorimotor period, (2) the preoperational stage, (3) the concrete-operational stage, and (4) the period of formal operations.

Applications of the Theory

Many of Piaget's concepts continue to have heuristic value even today and to provide hypotheses relevant to psychopathology. The notions of egocentrism, the invariant sequences of skill acquisition, and increasing differentiation (i.e., development rather than mere change) provide hypotheses regarding the behavior of children who have conduct problems and of adolescents who are lagging developmentally. Furthermore, Piaget's discoveries of the limits of young children's abilities have inspired cognitive educational strategies.

Criticisms of the Theory

Even though Piaget's influence has been tremendous, crucial features of organismic theory have been refuted. Children have repeatedly been shown to be more competent than Piaget suggested they could be at a particular age. Piaget's proposed cross-domain universality in type of thought has been shown to be false, suggesting to some scholars that the stage concept is faulty. It has been replaced by concepts of learning strategies, information-processing patterns, and the parsing of multiple components in complex task completion.

Attachment Theory

Bowlby generated a theory of attachment that has had enormous influence in contemporary developmental psychology. According to Bowlby, infants are born with innate tendencies to seek direct contact with an adult (usually the mother). In contrast to Freud's perspective that early attachment-seeking is a function of a desire for the mother's breast (and food), Bowlby argued that attachment seeking is directed toward social contact with the mother (the desire for a love relationship) and driven by fear of unknown others. By about 6–8 months of age, separation from the mother arouses distress, analogous to free-floating anxiety. The distress of a short-term separation is replaced quickly by the warmth of the reunion with the mother, but longer separations (such as those occur in hospitalization or abandonment) can induce clinging, suspicion, and anxiety upon reunion. Similar effects are seen in older children until individuation occurs, at which point the child is cognitively able to hold a mental representation of the mother while she is gone, enabling the child to explore novelty.

Bowlby hypothesized that individual differences exist in patterns of parent-infant relationship quality and that the infant acquires a mental representation (or working model) of this relationship that is stored in memory and carried forward to act as a guiding filter for all future relationships. This working model of relationships generalizes to other contexts and allows future interactions to conform to the working model, thereby reinforcing the initial representation of how relationships operate. Thus, the quality of the initial parent-infant relationship has primary and enduring effects on later adjustment, relationships, and parenting.

Individual differences in attachment patterns have been assessed through a laboratory procedure called the Strange Situation, devised by Ainsworth. The parent and 12-month-old child are brought to an unfamiliar room containing toys, after which a stranger enters. The parent then leaves the room for a short period, followed by a reunion. The child's behavior, especially toward the parent upon reunion, is indicative of the quality of the overall parent-child attachment. Attachment classifications are summarized in Table 8–3.

About two thirds of children fit the “secure” response pattern (type B), in which they demonstrate distress when the parent leaves and enthusiasm (or confident pleasure) upon her return. An “avoidant” response pattern (type A) involves little distress and little relief or pleasure upon reunion with the parent. A “resistant or ambivalent” response pattern (type C) involves panicky distress upon the parent's departure and emotional ambivalence upon reunion (perhaps running toward the parent to be picked up but then immediately, angrily struggling to get down). Recently, scholars have identified a fourth class of response, “disorganized” (type D, empirically linked to early physical or sexual maltreatment), in which the child's behavior involves great distress and little systematic exploration or seeking of adults.

Applications of the Theory

Follow-up studies have shown that these patterns of attachment are somewhat stable over time (although not strongly correlated across relationships with different adults) and predictive of behavioral adjustment in middle childhood. Infants of types A, C, and D are all at risk for later maladjustment, although more specific patterns of outcome for each type have not been detected reliably. Developmental scholars have created methods for assessing relationship quality and working models at older ages and have related these assessments to current behavioral functioning.

Criticisms of the Theory

Critics of attachment theory suggest that the initial relationship does not determine destiny as strongly as Bowlby argued, and that long-term predictive power is due partly to consistency in the environment that led to the child's initial response pattern. Attachment theory has been used to condemn the practice of early out-of-home daycare (because it interferes with the development of a secure attachment with the mother), even though most studies find little long-term effect of such care after other confounding factors (e.g., economics, family stability, stress, later caregiving) are controlled. More broadly, the reversibility of the effects of early social deprivation and trauma remain controversial. The current general conclusion is that even though early experiences shape later experiences through the filter of mental representations, the plasticity of the human organism is greater than previously hypothesized, but only up to a point.

Social Learning Theory

Bandura's social learning theory, though acknowledging the constraints of biological origins and the role of neural mediating mechanisms, emphasizes the role of the individual's experience of the environment in development. Other learning theories are based on the organism's direct performance of behaviors, whereas social learning theory posits that most learning occurs vicariously by observing and imitating models. For survival and growth, humans are designed to acquire patterns of behavior through observational learning. Social behavior in particular is a function of one's social learning history, instigation mechanisms, and maintaining mechanisms.

Four processes govern social learning: (1) attention, which regulates exploration and perception; (2) memory, through which observed events are symbolically stored to guide future behavior; (3) motor production, through which novel behaviors are formed from the integration of constituent acts with observed actions; and (4) incentives and motivation, which regulate the performance of learned responses. Development involves biological maturation in these processes as well as the increasingly complex storage of contingencies and response repertoires in memory.

Instigation mechanisms include both biological and cognitive motivators. Internal aversive stimulation might activate behavior through its painful effect (on hunger, sex, or aggression). Cognitively based motivators are based on the organism's capacity to represent mentally future material, sensory, and social consequences. Mentally represented consequences provide the motivation for action.

Maintaining mechanisms include external reinforcement (e.g., tangible rewards, social and status rewards, reduction of aversive treatment), punishment, vicarious reinforcement by observation, and self-regulatory mechanisms (e.g., self-observation, self-judgment through attribution and valuation, self-applied consequences). Development in social learning theory is decidedly not stage-like and has few constraints. For example, Bandura argued that even relatively sophisticated moral thought and action are possible in young children, given relevant models and experiences.

Applications of the Theory

Social learning theory has been applied most effectively to aggressive behavior, where it has provided powerful explanations for the effects of coercive parenting, violent media presentations, and rejecting peer interactions on the development of chronic aggressive behavior. Furthermore, it provides the basis for most current behavior-modification interventions in clinical practice.

Criticisms of the Theory

Critics dispute the primacy of cognitive mediation in understanding learning effects and the relative emphasis on environment over genetic and biological influences.

Attribution Theory

The emphasis on cognition in social learning theory is largely consequence oriented (i.e., based on individuals’ cognitions about the likely outcomes of their behavior). Attribution theory is more concerned with how people understand the causes of behavior. Its origins are in the naïve or common-sense psychology of Heider, who suggested that an individual's beliefs about events play a more important role in behavior than does the objective truth of events. For social interactions, an individual's beliefs about the causes of another person's behavior are more crucial than are the true causes. For example, in deciding whether to retaliate aggressively against a peer following a provocation (such as being bumped from behind), a person often uses an attribution about the peer's intention. If the peer had acted accidentally then no retaliation  occurs, but if the peer had acted maliciously then retaliation may be likely. The perceiver's task in social exchanges is to decide which effects of an observed action are intentional (reflecting dispositions) and which are situational.

When judging whether another person's behavior (such as aggression) should be attributed to a dispositional rather than a situational cause, perceivers use mental heuristics, such as correspondent inference and covariation. Perceivers examine whether the person's actions are normative or unique (if unique, they may indicate a dispositional rather than situational cause). They examine the other person's behavioral consistency over time and distinctiveness across situations (if the behavior is consistent, it more likely reflects a disposition). Finally, they examine whether the action has personal hedonic relevance to the perceiver (if the action is relevant to the perceiver, perceivers tend to attribute dispositional causes).

These principles predict the kinds of causal attributions that people make about the events around them, the circumstances under which people will make errors in inference, and people's behavioral responses to events. Extensions of attribution theory have addressed differences in the causal attributions made by people about themselves versus others (actor–observer effects), the kinds of explanations that people give for their own behavior and outcomes (internal versus external attributions), and the circumstances under which people spontaneously make attributions.

Applications of the Theory

Attribution theory has been applied to problems in several domains of psychiatry and health. Studies have shown that attributions predict behavioral responses to critical events such as interpersonal losses and failure. People who attribute their failure to a lack of ability on their part are likely to give up and to continue to fail, whereas people who attribute their failure to a lack of effort are likely to intensify future efforts to succeed. People who regularly attribute their failures to global, stable, and internal causes (i.e., they blame themselves) are at risk for a mood disorder and somatization disorder. People who attribute their own negative outcomes to the fault of others are likely to direct aggression toward the perceived cause of the outcome (and to develop a conduct disorder). Interventions have been developed to help people redirect attributions more accurately or more adaptively, most notably in cognitive therapies for depression.

Criticisms of the Theory

Until recently, the problem of development was relatively ignored in attribution theory. Studies only recently have begun to address topics such as the age at which attributions come to be made spontaneously, the relevance of spontaneous attribution tendencies for age differences in depression, and the experiential origins of chronic attributional tendencies.

Social Information-Processing Theory

The comprehensive extension of social learning theory and attribution theory is to consider all of the mental processes that people use in relating to the social world. Simon's work in cognitive science forms the basis for social information-processing theory. This theory recognizes that people come to social situations with a set of biologically determined capabilities and a database of past experiences (Figure 8–3).

They receive as input a set of social cues (such as a push in the back by a peer or a failing grade in a school subject). The person's behavioral response to the cues occurs as a function of a sequence of mental processes, beginning with encoding of cues through sensation and perception. The vastness of available cues requires selective attention to cues (such as attention to peers’ laughter versus one's own physical pain). Selective encoding is partially predictive of ultimate behavior. The storage of cues in memory is not veridical with objective experience. The mental representation and interpretation of the cues (possibly involving attributions about cause) is the next step of processing. A person's interpretation of a stimulus is predictive of that person's behavioral response (e.g., a hostile attribution made about another's ambiguously provocative push in the back will predict a retaliatory aggressive response). Once the stimulus cues are represented, the person accesses one or more possible behavioral responses from memory. Rules of association in memory, as well as the person's response repertoire, guide this retrieval. For example, one person might follow the rule “when intentionally provoked, fight back”; whereas another person might follow the rule “when provoked, run away.” Accessing a response is not the same as responding behaviorally, however, as in the case of a withheld impulse. The next step of processing is response evaluation and decision making, wherein the person (not necessarily consciously) evaluates the interpersonal, intrapersonal, instrumental, and moral consequences of accessed behavioral responses and decides on an optimal response. Clearly, evaluations that a behavior is relatively likely to lead to positive consequences are predictive of that behavioral tendency. The final step of processing involves the transformation of a mental decision into motor and verbal behavior.

Social information-processing theory posits that people engage in these mental processes over and over in real time during social interactions and that within particular types of situations, individuals develop characteristic patterns of processing cues at each step in the model. These patterns form the basis of psychopathologic tendencies. For example, in response to provocations, one person might regularly selectively attend to certain kinds of cues (such as threats), attribute hostile intentions to others, access aggressive responses, evaluate aggressing as favorable, and enact aggression skillfully. This person is highly likely to develop conduct disorder. Likewise, in response to academic failure, another person might selectively attend to his or her own contributing mistakes, attribute the outcome to personal failure, access self-destructive responses, evaluate all other responses as leading to further failure, and enact self-destructive responses effortlessly. This person is likely to develop dysthymic disorder or major depressive disorder.

Applications of the Theory

Social information-processing theory has been used successfully to predict the development of conduct problems in children and depressive symptoms in adolescents. Not all individuals with conduct problems display the same deviant processing patterns at all steps of the model; however, most people with conduct problems display at least one type of processing problem. Some children with conduct problems show hostile attributional tendencies, whereas others evaluate the likely outcomes of aggressing as positive. These processing differences accurately predict subtypes of conduct problems: Children with hostile attributional tendencies display problems of reactive anger control, whereas children who make positive evaluations of the outcome of aggressing display instrumental aggression and bullying.

The development of processing styles has shed light on the development of psychopathology. For example, children with early histories of physical abuse are likely to become hypervigilant to hostile cues and to display hostile attributional tendencies. These tendencies predict later aggressive-behavior problems and account for the empirical link between early physical abuse and the development of aggressive-behavior problems.

Social information-processing theory has the potential to distinguish among types of psychopathology. In one investigation, groups of children with depressive, aggressive, comorbid, or no symptoms were found to display unique profiles of processing patterns. The aggressive group tended to attribute hostile intentions to others, to access aggressive responses, and to evaluate the outcomes of aggressing as favorable. The depressive group, in contrast, tended to attribute hostile intentions to others as well, but they also attributed the cause of others’ hostile intentions to self-blame, and they accessed self-destructive responses and evaluated aggressive responses negatively.

Social information-processing theory has suggested interventions designed to help people construe situations differently and to act on the social world more effectively. For example, one intervention has been directed toward helping aggressive adolescents attribute interpersonal provocations in a less personalized and hostile way. This intervention has been successful in reducing the rate of aggressive behavior in these adolescents, relative to untreated control subjects.

Criticisms of the Theory

By focusing on in situ mental actions, processing theory relatively neglects enduring structural components of personality that are emphasized in psycho-analytic and Piagetian theories. Another criticism is that social information-processing theory locates the sources of deviant behavior in the individual, in contrast to the broader social ecology.

Ecological Theory

Ecological theory evolved from the recognition that even though the environment has a major effect on development, many models of development have limited generalizability across contexts. Consider, for example, classic studies by Tulkin and his colleagues on the effect of mother–infant interaction patterns on the infant's development of language and mental abilities. This effect is stronger among socioeconomic middle-class families than among lower-class families. Likewise, Scarr has found that the magnitude of genetic influences on intellectual development varies according to the cultural group being studied. Greater genetic effects are observed in middle-class white groups than in lower-class African American groups. Among lower-class families, different influences on development are operating. Findings such as these led ecological theorists such as Lewin, Bronfenbrenner, and Barker to conclude that models of development are bounded by the context in which they are framed.

Ecological theory suggests that process models of development have no universality; rather, they must be framed within the limits of a cultural and historical context. This theory must be distinguished from the radical postmodernist perspective that scientific principles have no objective basis. Ecological theorists conceptualize the environment systematically and attempt to understand how it affects development.

Bronfenbrenner has articulated an ecological model that includes developmental influences at the individual (person), person-by-environment (process), and context levels. He categorizes contextual settings into three types: microsystems, mesosystems, and exosysterns. As discussed earlier in this chapter, the most proximal type is the microsystem, which includes the immediate physical and social environment. Examples of microsystems are homes, schools, playgrounds, and work places. Each microsystem has a structure and a set of rules and norms for behavior that are fairly consistent across time. Developmental scientists study processes within each of these settings, and ecologists warn them not to overgeneralize process phenomena from one microsystem to another.

The next type is the mesosystem, which is defined as a combination of microsystems that leads to a new level of developmental influence. For example, in understanding the effects of parental versus peer influences on adolescent development, one must consider not only each of the family and peer microsystems but also the effect of the combined mesosystem, that is, the effect of the conflict between the family's values and the peer group's values on the child's development.

The final type is the exosystem, a combination of multiple mesosystems. Research on the effects of maternal employment on child development has been enhanced by an understanding of this exosystem. That is, in order to understand how maternal employment affects a child's social development, one must understand not only the family and work context but also the cultural and historical contexts of women's employment.

Applications of the Theory

Ecological theory has led clinicians to question the generalizability of their practices across cultural, gender, and ethnic groups. Group-specific interventions are being developed. Ecological theory has also led to policy changes in the funding of research at the federal level, in that large research studies are now required to address questions of generalizability across groups. Finally, ecological theorists have pressed clinicians to consider the possibility that interventions at a broader level might exert a powerful effect at the microsystem level.

Criticisms of the Theory

Ecological theory is not a theory in the formal sense. Rather, it is a structured framework for identifying influences at numerous levels. Thus, it is not falsifiable. Its value is in alerting clinicians to factors that otherwise might be neglected.

It has been increasingly recognized that interactionist models of development apply to most forms of psychopathology. These models focus on the confluence of forces that must coalesce in order for a disorder to develop. The most basic of these models is the diathesis–stress model. A diathesis is a dispositional characteristic that predisposes an individual to a disorder. The disposition may be biological (as in a genetic predisposition for schizophrenia), environmental (as in poverty), or cognitive (as in low IQ). A disorder is probabilistically related to the presence of a diathesis, but the process of development of psychopathology requires that the individual with the diathesis also be exposed to a stressor, which, again, might be biological or environmental. Only those individuals with both diathesis and stressor are likely to develop the disorder.

Consider the diathesis–stress model of major depressive disorder. According to this model, individuals who display the cognitive diathesis of self-blame for failure are at risk for the development of depression, but only if they subsequently experience a stressor that is linked to the diathesis (such as failure). Statistically, this model hypothesizes an interaction effect, and it has been supported for a variety of problems, from depression to physical illness.

Theorists have noted that individual and environmental factors interact not only in static models such as the case of major depressive disorder but also over time in transactional models. These models articulate the reciprocal influences between person and environment and the unfolding of disorder across experience. Finally, theorists have come to recognize that the unfolding occurs in nonlinear, nonuniform ways that lead to qualitative changes in the individual, as in dynamic systems (see “Major Principles of Ontogeny and Phylogeny” earlier in this chapter). Dynamic systems models are borrowed from phenomena in physics to describe the development of novel behavior in infancy (such as the onset of locomotion and language) and have the potential to be applied to the development of novel deviant behavior in psychopathology.

One of the most powerful methods in developmental clinical research is that of life-course prospective inquiry, closely linked to developmental epidemiology. By identifying an important sample (either a high-risk sample or a representative sample) and then following that sample with repeated assessments across time using hypothesis-driven measures, researchers have been able to identify risk factors in the development of a disorder, moderators of that risk, and mediating processes in the etiology of the disorder. Two such longitudinal studies are described in this section as examples of ongoing research in this field.

The Development of Depression Project

The Development of Depression Project has tested the diathesis–stress model of the development of major depressive disorder in adolescents. According to Garber, some children develop cognitive styles for attributing their failures and losses to internal, global, and stable characteristics of themselves, and they begin to have negative automatic thoughts in response to life events. Later, when confronted with failures and losses, these children are at elevated risk for developing major depressive disorder. It is the interaction of the cognitive diathesis and the life stressor, not either factor in isolation that leads to depression. In order to rule out competing hypotheses that cognitive styles or problem life events result from, rather than lead to, depression, a research design is needed that follows children across time.

The research strategy in this study was to identify a sample of children prior to adolescence; to assess cognitive diatheses, life events, family processes, and psychopathology in this sample at that time; and then to follow the children with repeated assessments throughout adolescence in order to determine which ones develop depression following common stressors of adolescent life.

At the first wave of assessment in sixth grade, 188 children and their parents were assessed for psychopathology, life events stressors, family processes, and most pertinent, the cognitive diathesis for depression. Analyses of the initial wave revealed that children of depressive parents demonstrated more subthreshold symptoms of depression and more negative attributional styles than did the children of nondepressed parents. Even though these findings are consistent with the hypothesized model, the critical test would come over time if initial depressive symptom levels could be controlled statistically to see whether attributional styles and life stressors interact to predict onset of depressive disorder. Annual follow-ups through young adulthood indicate that among those children who displayed at least some depressive symptoms, controlling for initial depressive symptom levels, the interaction of early cognitive diathesis and subsequent stressful life events significantly predicted later depressive symptom levels as determined by psychiatric interviews. That is, only those children with a combination of initial negative automatic thoughts and subsequent stressful life events showed elevated depressive symptoms later; all other groups showed lower levels of symptoms. This is a moderator effect: The cognitive diathesis moderates (or alters) the effect of stressful life events on depressive symptoms.

This prospective study has provided empirical support for a model in which early family interactions involving psychological control and lack of acceptance lead a child to develop cognitive styles of negative self-worth, negative automatic thoughts, and negative attributions for failure. Later, in adolescence, those children who show the unique combination of experiencing stressful life events and having negative automatic thoughts about those events are most likely to develop depression. This model integrates biological (genetic risk), family process, cognitive, and ecological (stressful life events) factors in the onset and course of depression. It also suggests three points for intervention with children who are at risk for depression. First, early family interactions involving acceptance and control might be targeted through parent training. Second, the child's cognitive styles might be addressed in brief preventive cognitive therapy. Third, the child's ecology might be modified by altering the child's exposure to stressful life events (or at least the child's experience of inevitable stressful events).

The findings of this seminal study have been used as the empirical basis for innovative intervention programs to prevent depressive disorder in early adolescents. Prevention scientists, including Gregory Clarke, Martin Seligman, Timothy Strauman, and Judy Garber, have developed individual- and group-based multisession programs designed to help adolescents alter their cognitive responses to failure, loss, and other stressors. Evaluation of these programs through randomized trials has revealed proximal success in altering targeted cognitive styles and distal success in preventing depressive symptoms in response to future stressors.

The Child Development Project

The Child Development Project was initiated to understand the role of family experiences and patterns of social information processing in the development and growth of aggressive conduct problems and conduct disorder. The design is a developmental epidemiologic one: 585 preschool children at three geographic sites were selected randomly at kindergarten matriculation to participate in a 20-year longitudinal study. The hypotheses guiding the study were, based on the social learning theory in developmental psychology and the social information-processing theory in cognitive science, namely, that early family experiences of physical abuse and harsh discipline would predict later serious conduct problems; and that this relation would be mediated by the child's intervening development of problematic patterns of processing social information.

In-home family interviews and direct observations of family interactions provided information about the child's experience of physical abuse and harsh discipline in the first 5 years of life. About 12% of this random sample was identified as having experienced physical abuse at some time in their lives, a high rate that is consistent with national surveys of community samples. At subsequent annual assessments, video-guided interviews with each child provided measures of the child's patterns of social information processing. Finally, teacher ratings, peer nominations, direct observations, and school records provided evidence of externalizing conduct problems. The study followed this sample from preschool into high school.

Analyses indicated that the physically abused group of children had a fourfold increase in risk for clinically significant externalizing problems by middle school. This risk could not be statistically accounted for by confounding factors, such as socioeconomic status, child temperament, or exposure to other violent models. Thus, it seems that the experience of harsh parenting, especially if extreme, is partially responsible for conduct problems in some children.

Consistent with the original hypotheses, the physically abused children were also at risk for problems with social information processing. Specifically, physically abused children were relatively likely to become hypervigilant to hostile cues, to develop hostile attributional biases, to access aggressive responses to social problems, and to believe that aggressive behaviors lead to desired outcomes. Also consistent with hypotheses, children who demonstrated these processing patterns were likely to develop clinically significant externalizing problems in middle school and high school. Finally, the mediation hypothesis was supported, in that the child's social information-processing patterns accounted for about half of the statistical relation between early physical abuse and later conduct problems.

Developmental psychology plays an important role in psychiatric science and practice. Concepts such as the orthogenetic principle, ontogeny, phylogeny, age-norming, and developmental trajectories can help the practicing psychiatrist to place a patient's current symptoms into developmental and ecological context. Common patterns in the development of psychopathology (e.g., biosocial interactions, multiple pathway models, mediational models, and bidirectional effects) enrich the psychiatrist's understanding of the etiology of psychiatric disorders.

Even though major developmental theories (e.g., temperament, attachment, social learning) have historical significance, most contemporary thinking is not directed at contrasting these theories at a macrolevel. Rather, it is understood that psychiatric phenomena usually involve complex interactions of factors at multiple levels. Current research is aimed at understanding how variables implicated by various theories interact to produce psychiatric disorder, rather than proving one general theory to be more meritorious than another.

The relation between developmental psychology and psychiatry is reciprocal. That is, knowledge gained from developmental theory and empirical findings has been useful to psychiatrists in both scientific understanding and practice, and the findings and concerns of psychiatrists have modified developmental theory and guided developmental empirical inquiry. These disciplines have been fused even more tightly in the emerging discipline of developmental psychopathology, which seeks to understand the etiology, process, and life-course of psychiatric phenomena.