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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).
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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.
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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.
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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.
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The Orthogenetic Principle
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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., ...