Developmental psychology is the branch of psychology dedicated to identifying and explaining the continuities and changes that individuals display over their lifetimes. In particular developmental psychologists seek to understand the mechanisms or factors that are deemed responsible for the immense changes that occur in human thought, behavior, biology, and emotion from the very beginning of life through to the end—from "womb to tomb" (Shaffer, Wood, and Willoughby 2002).
Historically, early theories of development focused on trying to explain the development that occurs primarily during the first decade of life, with a focus on infancy and early child development. Scant attention was paid to the development that occurs during adolescence and on into adulthood. Societal changes that occurred during the 1950s and 1960s, however, led to a critical shift in theories and research in the field of developmental psychology. With respect to adolescence, for instance, the youth movements of the 1960s brought a new interest in understanding the teenage years and led to a marked theoretical alteration in the understanding of adolescence. Before then little attention had been paid to the empirical investigation of adolescents, and the extant theories of adolescence, primarily based on clinical experiences and anecdotal reports, portrayed the teen years as a time of "storm and stress"—a time during which individuals experience severe emotional turmoil and disturbance (e.g., Hall 1904). But data collected from adolescents themselves revealed that the teen years were not as tumultuous as previously assumed and that in fact the majority of adolescents (80%) reported traversing the teen years with little turmoil, relating well to their families and peers, and being comfortable with their social and cultural values (Offer and Schonert-Reichl 1992).
THEORETICAL FRAMEWORKS
Early twenty-first century views of development examine development across the life span: the prenatal period, infancy and toddlerhood, the preschool period, middle childhood, adolescence, young adulthood, middle adulthood, and late adulthood. A life span approach to development encompasses the scientific study of human growth, change, and stability (Feldman 2006). Researchers with this perspective seek to unravel universal principles of development, characteristics, and traits that differentiate people from one another, with a focus on physical, cognitive, personality, and social development. Demographic changes since the 1980s have spurred a new conception of development for the period identified as "emerging adulthood," which spans the ages eighteen to twenty-five (Arnett 2000).
In contrast to the life span development approach, another theoretical framework for understanding development over time is the life course perspective. Life course theory emerged in the 1960s from the need to understand how individual lives are socially patterned over time and to examine the processes by which lives are changed by changing environments in which time, context, and process are an explicit part of the analysis. More specifically, life course researchers take into account both stability and change in lives as they unfold across time and generations and in historical, social, and cultural contexts.
The life course approach is an increasingly influential paradigm in social scientific thinking. In the words of Anne Colby, this theoretical approach represents "one of the most important achievements of social science in the second half of the 20th century" (Colby 1998, p. viii). One of the pioneers in this field is Glen Elder Jr., who studied children of the Great Depression, emphasizing how individual lives are socially patterned over time and the processes by which lives are changed by changing environments (Elder and Shanahan 2006).
The science of developmental psychology lacks a comprehensive and widely accepted developmental theory that unifies the field (Cole, Cole, and Lightfoot 2005). Instead, many different theories have been proposed in the study of development, demonstrating how different theories lead to different explanations of behavior across the life span. The most influential and enduring theoretical frameworks have included the psychoanalytic, learning, cognitive-developmental, and ecological systems viewpoints. Sigmund Freud was among the first to emphasize the centrality of emotional life to the formation and function of personality development (Cole, Cole, and Lightfoot 2005). His psychoanalytic theory was rooted in the idea that development moves through a series of stages in which individuals confront conflicts between their biological drives and their social expectations. Freud envisioned the immense power of the unconscious as a determinant of behavior and argued that development is largely molded by experiences in the first years of life. Although psychoanalytic theory has profoundly influenced psychology, among other fields, it is subject to criticism. Even among his own circle of disciples, Freud’s theories did not go unchallenged (Passer, Smith, Atkinson, et al. 2005). Although neoanalytic contemporaries of Freud, such as Alfred Adler, Karen Horney, Erik Erikson, and Carl Jung, agreed on the importance of both the unconscious and of childhood experiences, most argued that Freud did not give social and cultural factors sufficient importance in the role of development. Indeed because of the many criticisms leveled at Freud’s theories in terms of generalizabilty and testability, few present-day developmentalists are strong supporters of Freud’s theories (Shaffer, Wood, and Willoughby 2002).
In contrast to psychoanalytic theories, learning theories emphasize that development occurs as a result of behaviors learned through associations with different kinds of consequences. The most influential proponents of this perspective, John B. Watson and B. F. Skinner, argued that individuals tend to repeat behaviors that have resulted in rewards or that have allowed them to avoid unpleasant consequences. Social learning theorists such as Albert Bandura expanded upon traditional learning views to consider that a great deal of learning develops through the observation of others in the social context. Through a process known as modeling, children come to imitate behaviors they have seen others do, especially if they observe such behaviors to have positive consequences (DeHart, Sroufe, and Cooper 2004). Perhaps the greatest contribution of the learning viewpoint to understanding development has been the wealth of information gleaned through tightly controlled experiments. Learning theories are precise and testable and have helped developmentalists begin to understand why and how people form emotional attachments, adopt gender roles, make friends, and learn to abide by laws and rules (Shaffer, Wood, and Willoughby 2002). Nonetheless, the learning approach is a grossly oversimplified account of human development; it tends to overlook the contexts in which development occurs and often fails to recognize the cognitively active role that individuals play in their own development.
The cognitive-developmental perspective addresses some of these criticisms by focusing on the view that individuals actively construct a system for understanding the world rather than passively acquiring new information through simple learning mechanisms. Cognitive develop-mentalists seek to understand and explain the normative development of reasoning and thinking skills and argue that such skills progress through a universal sequence of invariant and qualitatively different stages. Jean Piaget is the most prominent developmental psychologist of the twentieth century, having contributed more to our understanding of cognitive development than any other scholar (Shaffer, Wood, and Willoughby 2002). Piaget’s theories legitimized the study of children’s thinking, linked moral development to cognitive development, and contributed to developmental research in social cognition—the kind of thinking that people display about the thoughts, feelings, motives, and behaviors of themselves and other people (Shaffer, Wood, and Willoughby 2002). Although critics have challenged the sequence of Piaget’s stages and recognize that he underestimated the ages at which cognitive skills develop, it is almost impossible to exaggerate the impact that Piaget’s thinking has had on developmental psychology (Beilin 1994).
A final theoretical framework is ecological systems theory, posited by Urie Bronfrennbrenner (1979). This perspective begins by assuming that natural environments are the major source of influence on developing persons (Shaffer, Wood, and Willoughby 2002). The ecological framework views individuals in the context of all the various settings they inhabit on a daily bases (microsystems). These settings are related to one another in a variety of ways (mesosystems), which are in turn linked to settings and social institutions where an individual is not immediately present but which have an important influence on his or her development (exosystems). All of these systems are organized in terms of the culture’s dominant beliefs and ideologies (the macrosystem). Although the ecological systems perspective has gifted developmental psychology with an understanding of the complexities of the natural environment, the theory fails to explain how individuals process and learn from environmental information and is therefore not a complete account of how humans develop (Shaffer, Wood, and Willoughby 2002).
INVESTIGATIVE METHODS
Without a unified theory, how do developmental psychologists know anything about human development? Since the 1990s a variety of methods has been refined for gathering information about how development occurs (Cole, Cole, and Lightfoot 2005). Among the most widely used are naturalistic observations, survey research, and research experiments. However, no single method can answer every question about human development; each approach has its own strengths and limitations. Various approaches have a strategic role to play, dependent upon the topic under investigation and the answers being sought.
The most direct way to gather information about how development occurs is through naturalistic observation. By definition, naturalistic observation involves observing and recording behavior in naturally occurring situations without trying to manipulate the environment. Naturalistic observations allow developmentalists to observe how individuals behave in everyday life. However, such an approach is not without its limitations. For example, when people know they are being watched, they often behave differently than they normally would. In addition researchers often enter observational settings with expectations about what they are going to see and inevitably observe selectively in accordance with those expectations. Nonetheless, observational methods are a keystone of developmental research and a critical source of data about development (Cole, Cole, and Lightfoot 2005).
Researchers who opt for survey methods utilize structured questionnaire or interview techniques to ask participants questions related to such aspects of development as perceptions, feelings, or beliefs. Despite obvious shortcomings, such as attempts by respondents to present themselves in socially desirable ways, survey research is an excellent method for obtaining large amounts of information, often from a large number of participants, in relatively short periods of time.
A final investigative approach is the psychology experiment. In a true experiment the researcher controls conditions and systematically manipulates one or more variables so as to rule out all other influences on development except the one being investigated. The clear strength of the experimental method is its unique ability to isolate causal factors. That is, by controlling extraneous variables that may be influencing development, researchers can be confident that the variable of interest does indeed have an effect. A major drawback to experimental research is that the findings are not always generalizable to everyday settings, given that people do not always respond in the laboratory the way they do in the natural environment. Thus, as with the myriad of theories utilized to explain development, there are numerous approaches for investigation in the field of developmental psychology.
