Theories and Models of Development
Theories are important to the study of development for a number of reasons. They organize and prioritize large amounts of data regarding infant development, indicating which are the most sa-lient and why. Often, they also explain the importance of the early years for subsequent development, indicating how developmen-tal issues are related to broader issues of the lifespan. Generally, they move beyond mere descriptions of behavior and attempt to explain why individuals are motivated to behave in certain ways at certain times. Finally, they may generate meaningful and test-able hypotheses for empirical research.
On the other hand, theories have inherent liabilities. A selective focus on one theory may obscure others of equal or greater value. Theories also inevitably lead to oversimplification of complex processes and events. They may create biases that af-fect how we interpret observations and how we make inferences from these observations. The history of psychology is filled with examples of adherence to a particular point of view, making it impossible to see disconfirming information. All of these factors warrant caution about the uncritical use of theories to understand development. A useful theory is one which is developmental, in-tegrative, contextualist, constructionist and perspectivist in na-ture, discounting its own absolute claim to truth and integrating as many relevant approaches as possible. An integrative devel-opmental theory accounts for the dynamic interactions of biol-ogy (including neuroanatomy, genetics, neurotransmitters, etc.), relationships (including parental, sibling, peer and wider social
groups), culture (including cultural norms for individual and col-lective development), and technology (including medication, in-formatics, etc.) (Wilber, 2000).
Table 7.2 presents a brief summary of some of the major theories of development as they pertain to the first 3 years of life. Although others could have been selected, those presented have been most influential with regard to clinical practice and research on early development. As noted in Table 7.2, the theories vary with regard to their particular focus of development, although most use stages to describe periods of discontinuity.
There has been a scientific preoccupation with defining the relative contributions of genetic endowment and environmental experience on the course of human development. While early be-havioralists took the extreme view that children can be shaped al-most exclusively by their environments, today evidence supports the view that genes and experience interact continuously overtime in a transactional manner that leads to the unique develop-ment of an individual. The study of environmental contributions has steadily improved through the application of more careful methods of assessment and an appreciation of the value of exam-ining the many components of the early experience of children.
However, the most explosive advances in the understand-ing of human development have been made as specific gene sequences have been identified and linked to physical and be-havioral outcomes. In the past decade, the pace of new gene discovery has increased exponentially as a consequence of the success of the Human Genome Project. It is now estimated that human beings have approximately 38 000 to 40 000 genes. Deter-mining the precise number has been elusive as it has been neces-sary gradually to understand that human genes are more complex than the genes of simpler organisms. Specifically, many human genes produce multiple proteins. We are now learning about the degrees of genomic variability that exist between individuals, as well as beginning to understand how genes interact with each other and how they are regulated by the environment. A key fo-cus of new research is the discovery of how the passage of time and the gradual maturation of the individual affect the expression of genes that have remained silent but potentially ominous from the beginning of fetal development. Future studies of cohorts of infants who are at known genetic risk for a trait or illness maywell identify environmental factors associated with both the ex-pression and the suppression of gene expression.
The concept of studying development longitudinally has its origin in the studies of lives and was well established by Plu-tarch and popularized by Shakespeare. In many ways, biogra-phers strive to examine the origins of adult traits through consid-eration of the early experiences of their particular subject. This tradition was adopted by psychoanalysts who searched for the origins of psychopathology through the exposition of a “genetic formulation’’. The choice of the word “genetic’’ to modify a con-ceptual formulation based on the experience of the individual is somewhat ironic. The term has largely been abandoned, as these formulations had little to do with the function of individual genes. Nonetheless, this focus on the influence of early experi-ence on development may well have been a foreshadowing of the importance of intense early experience on gene expression. In all likelihood, the genetic formulations of the future will focus on how experience regulates gene expression at the molecular level.
The concept of parallel yet interacting lines of develop-ment was popularized by Anna Freud (1946) who created a classical monograph that articulated nine lines of development that were well described through adolescence. Although some of these conceptual lines have been abandoned, the overarching principle of a line of development has proven to have heuristic value. Table 7.3 lists four relevant developmental lines.
Other psychoanalysts have built on her model to create parallel lines extending into adulthood. Erikson (1963) further elaborated the evolution of domains of function in the creation of his epigenetic stage model, as presented in Figure 7.1. His para-digm continues to have a strong influence on psychiatric theory.
as is wellillustrated by Vaillant’s work who has extended the Eriksonian model by proposing two additional phases of the adult life-cycle, career-consolidation vs. self-absorption and keeper of the meaning vs. rigidity. The former acknowledges the importance of achieving a stable career identity in addition to the achievement of identity within one’s family of origin. The latter describes fur-ther Erikson’s concept of generativity beyond assuming sustained responsibility for building the community and for the growth, well-being and leadership of others. “Keeper of the meaning’’ and its virtue, wisdom, involve a nonpartisan and less personal approach to others and is to be distinguished from the tasks of a generative coach, partisan parent, or mentor from the tasks of a Supreme Court judge or chair of a historical society.
Although lines of development are attractive conceptually, they are a deceptively simplistic representation of the complex evolution of personality. The concept of “decalage’’ was put for-ward by Piaget (1952) to refer to a disengagement in the normal evolution of the parallel development of specific cognitive abili-ties. However, decalage is equally salient in the conceptualiza-tion of major distortions in emotional or social development.