Life Span Development

The objective of this paper is to briefly discuss how the study of human development emerged as a discipline over the centuries, and to compare and contrast the strengths and limitations of the major research methodologies utilized within developmental psychology.

Developmental psychology is referred to as a scientific study surrounding the psychological changes that occur within people as they age. Developmental psychology is also referred to as life-span psychology, the branch of psychology that is focused on the cognitive, motivational, psycho physiological, and social functioning that occurs throughout the human life span (Britannica, 2006). When traced back to the early 19th and 20th centuries, the primary focus of developmental psychologists was on children. Starting around 1950 the focus changed to include relationships between personality variables, child rearing, and the meaningful stages of adult psychology. (Britannica, 2006). In the last part of the 20th century developmental psychologist started to broaden their horizons to include the relation of heredity and environment, continuity and discontinuity in development, and the behavioral and cognitive elements in the development of the total person (Britannica 2006). Now the field of developmental psychology focuses research, methodology and theories to encompass the entire life span of a human being from conception to death. The roots of developmental psychology can be traced back to Heraclitus, Aristotle and Descartes (Wikipedia, 2006).

William Shakespeare also played a role in developmental psychology with his literary work "As You Like It" (Wikipedia, 2006). Shakespeare's character "Jacques" depicted the "seven ages of man" which included three stages of childhood and four stages of adulthood (Wikipedia, 2006). In 1911 Rudolf Steiner wrote an essay, "The Education of the Child" in which he presented the first three stages of childhood (Wikipedia, 2006). Both of these writers laid some ground work for stage theorists.

The most prominent theoretical perspectives that attempt to explain development are: Jean Piaget's' Stage Theory, Lev Vygotsky's Social Contextualism, and Urie Brofenbrenner's' theory of Development in Context or Human Ecology (Wikipedia, 2006). Other historical theories that continue to provide a basis for research are: Erik Erikson's eight stages of psychosocial development, John B. Watson's and B. F. Skinner's Behaviorism, along with Lawerence Kholberg's stages of moral reasoning (Wikipedia, 2006).

An overview of historical figures in developmental psychology would include Descartes, Locke, Rousseau, Darwin, Hall, Watson, Gesell, and Freud. Descartes, Rousseau, Darwin, and Gesell are all considered nativists. Nativism is the view the behavior is innate and is strongly influenced by genes (MacDonald, 2006). Rousseau (1712-1778), believed that children were born with a conscience, a sense of fairness and that nature is good until corrupted by society (MacDonald, 2006). Rousseau also believed that children are curious, exploratory and have to be at the appropriate developmental level in order to learn from instruction (MacDonald, 2006). Darwin (1809-1882), believed that important human behaviors were systems that evolved in order to serve certain functions (Macdonald, 2006). His influence in developmental psychology did not become prominent until about 1970 with the rise of the ethological perspective and sociobiology (MacDonald, 2006). Arnold Gesell (1880-1961) was considered both a maturationist, someone who believes that behavior is strongly influenced by genetics, and a nativist (Macdonald, 2006). He established norms and milestones of typical ages when children will exhibit certain developmental abilities that are still in uses today.

G. Stanley Hall (1844-1924), was the first man to receive a Ph. D. in psychology and he was the founder of the American Psychological Association (MacDonald, 2006). Hall was also a maturationist and the stages he developed include:

Infancy (0-4): Animal phase

Age 4-8: Hunting and Fishing cultures

Age 8-12: Savage and Primitive (tribal) human cultures.

Age 12-25: 18th century idealism

Age 25' : Contemporary civilization

John B. Watson (1878-1958), in his school of behaviorism, focused on studying characteristics that were observable and measurable. Watson has had a lasting influence on methodology and was referred to as one of the reasons we all have to take courses in statistics and experimental design (MacDonald, 2006). Last but not least on the contribution to developmental psychology list is Sigmund Freud (1856-1939). It was stated that psychoanalysis did not have a huge influence in developmental psychology except for with John Bowlby in the development of his theory of attachment (MacDonald, 2006). All of the above mentioned people contributed to the how and why human development emerged as a discipline, thus leading into an overview of the research methodologies used then, and now, to broaden understanding and the continued search of knowledge pertaining to developmental psychology.

Developmental psychology utilizes several research methods and studies, including habituation methodology, longitudinal studies, cross-sectional studies, cross-sequential studies, experimental studies, observational research, correlational research, true experiments, quasi-experiments and performance and ability studies. Habituation methodology is used to assess the performance of infants. The method is used to allow researchers to gather information concerning the types of stimuli an infant is able to discriminate between (Wikipedia, 2006). The infants are habituated to a particular stimulus and then they are tested using different stimuli to evaluate their ability to discriminate the differences between the habituated stimuli and the novel stimuli (Wikipedia, 2006). The infant controls the stimuli being presented giving researchers the means of measuring discrimination (Wikipedia, 2006).

In longitudinal studies the researcher observes many individuals born at or around the same time, referred to as a cohort, and then new observations are carried out as the members of the cohort group age. Longitudinal studies require extensive time and monetary allocations which make them unfeasible, at times,