full version Life Span Development Essay

Life Span Development

Category: Psychology

Autor: webster 03 February 2010

Words: 2195 | Pages: 9

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, in research. Another problem encountered in longitudinal studies is that people experience historical events that are unique to their particular generation, which would make the normative developmental trends universal to that particular cohort age only (Wikipedia, 2006). It is also stated that longitudinal studies are difficult to implement because the subjects in the initial study may move or drop out (SparkNotes, 2006). Cook and Campbell (1979) defined this method as a time series design with history being most serious threat to internal validity. History being defined as the events that occur between the times of testing. According to Baltes (1968), the longitudinal method rarely meets the criteria of selective sampling because most individuals that participate in the study are usually of higher intelligence and socioeconomic status (Baltes, 1968). According to Jarvik and Falek (1963), longitudinal studies suffer from selective survival meaning that individuals who survive may be qualitatively different than those who do not. This was also backed up by Campbell and Stanley (1963) with the realization that longitudinal studies can also suffer from selective drop-out/experimental mortality. All of this would lead to the conclusion that the longitudinal method could suffer from several selection biases (Woolf, 2006). The longitudinal method of research can suffer from testing effects and threats to internal validity (Woolf, 2006). The longitudinal method is also very time consuming, expensive to conduct and can only be used to describe changes in a particular group of individuals over a particular point in time.



In cross-sectional studies differences between individuals of different ages are observed at the same time. Less resources are required in this kind of study, but it may not be the most effective way to study differences between participants because of their exposure to different historical events within their lifetimes (Wikipedia, 2006). Cook and Campbell (1979) argued that the cross-sectional method is not a true design it is separate samples, which pose a threat to internal validity. In cross-sectional studies, age differences could be confounded with differences in generations or cohorts, and the researcher may not be able to differentiate between maturational differences and cohort differences (Woolf, 2006). The cross-sectional, like the longitudinal method, is used descriptively. The differences in age groups or cohorts in a cross-sectional design can be described, but the differences can not be definitively explained (Woolf, 2006).



A cross-sequential study combines the methodologies of the longitudinal and cross-sectional research designs. The researcher observes members of different birth cohorts at the same time, then tracks all participants over time to track the changes in each group. The purpose being to compare the differences and similarities in each cohort's development in order to determine what changes are attributed to the individual or historical environment and which changes are universal (Wikipedia, 2006). This type of study can be more costly and time consuming than a longitudinal study. All of the above mentioned studies are correlational research methods, not experimental designs. They are used commonly in the study of development because of ethical concerns and the conditions being studied.



There are four major classifications of research designs including observational, correlational, true-experiments and quasi-experiments. Included in observational research are case studies, ethnographic studies and ethological studies among others. Observational research is often qualitative in nature and surveys are often classified under this heading. Observational research can be problematic if it is not conducted very carefully. Once again, there could be problems with internal validity because the individual can be described but causation can not. The other problems with observational research can include construct validity, incomplete background work, and observer and experimenter biases or preconceived expectations.



Correlational research, in general, examines the co-variation of two or more variables. One of the ways correlational research is carried out is through the gathering of empirical data. Correlational research is often referred to as observational research, because nothing is manipulated by the experimenter or the individual conducting the research (Woolf, 2006). Correlational research is used as a way to begin research, first the variables are identified and defined, and then experiments are conducted.



True experiments are defined as experiments that are conducted where an effort is made to impose control over all the other variables except the on that is being studied (Woolf, 2006). True experiments have experimental or treatment groups, a control group, an independent variable and a dependent variable. There is random assignment within groups, and the experiment should be double blind, where neither the subject nor the experimenter knows who was assigned to what group.



Quasi-experiments are similar to true experiments, the difference being quasi-experiments use naturally formed or pre-existing groups. The variable that is studied is called a subject variable not an independent variable which limits the conclusions that can be drawn from the research study. Several variables could be the cause of the results gained from a quasi-experiment. Cross-sectional and longitudinal designs are examples of quasi-experimental research.



All of the research designs and studies have their strengths and weakness. There are ethical concerns when conducting research with humans, and the fact that even if you have a group of people the same age they may not have similar experiences. There is always a threat to the internal validity of any study because human beings make mistakes. The observer will always come into the experiment or research with biases and beliefs that they want to be true or proved. It would be hard to rule out all personal biases and beliefs. All that can be done is to use each research methodology to the best of the observer and experimenters abilities and continue research until the end of time. Since we do not have people lining up to be research guinea pigs the options that are there have to be used, checked, and double checked again, until a conclusion can be drawn. Even if the conclusion is backed up by evidence for now, there is no guarantee that it will not change with research in the future.



Developmental psychology, (2006). Encyclopedia Britannica. Retrieved April 4, 2006, from Encyclopedia Britannica Premium Service http://wwwa.britannica.com/eb/article-9030150



Developmental psychology, (2006). Wikipedia. Retrieved April 3, 2006, from http://en.wikipedia.org/wiki/Developmental_psychology



MacDonald, K., 2006. Historical figures in developmental psychology. Retrieved April 3, 2006 from http://www.cslub.edu/~kmacd/361history.html



Benson, E., (2006). SparkNote on Introduction to developmental psychology. Retrieved April 4, 2006 from http://www.sparknotes.com/psychology/developmental/intro



Woolf, L., (2006). Developmental research methods. Retrieved April 3, 2006 from http://www.webster.edu/~woolflm/methods/devresearchmethods.html