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Research Concepts

Whether or not a particular discipline, such as psychology, is a science has more to do with the methods used than with the particular subject area studied. An area of inquiry is a scientific discipline if its investigators use the scientific method—a systematic approach to researching questions and problems through objective and accurate observation, collection and analysis of data, direct experimentation, and replication of these procedures. Scientists emphasize the importance of gathering information carefully and accurately, and researchers strive to remain unbiased when evaluating information, observing phenomena, conducting experiments, and recording procedures and results. Researchers also recognize the value of skepticism and the necessity of having their findings confirmed by other scientists.

Developmental psychology research is the scientific means of acquiring information about groups and individuals regarding various aspects of human development. A developmental psychologist begins a research study after developing ideas from a theory, or an integrated set of statements, that explain various phenomena. Because a theory is too general to test, the investigator devises a hypothesis—a testable prediction—from the theory and tests the hypothesis instead of a general theory. The results of the research study either disprove or do not disprove the hypothesis. If the hypothesis is disproved, it cannot be used to make predictions, and the investigator must question the accuracy of the theory. If the hypothesis is not disproved, the scientist can use it to make predictions about the phenomena that he or she is studying. These predictions may help scientists do one of the following:

* Form explanations of the causes of the phenomena.
* Draw conclusions about how the phenomena will affect groups and individuals.

A goal of developmental research is to discover the developmental similarities, differences, patterns, and trends of the population group that is under investigation. A population is a body of persons having qualities or characteristics in common. Members of a population who participate in a study are referred to as subjects or respondents. When the characteristics of a portion of the population are representative of the characteristics of the entire population, scientists can apply, or generalize, their findings from the sample to the population as a whole. The best and most representative sample is a random sample, in which each member of a population has an equal chance of being chosen as a subject.

In quantitative research, information is collected from respondents (for example, the number of years that they have been in college) and converted into numbers (junior equals 3; senior equals 4). In qualitative research, information collected from respondents takes the form of verbal descriptions or direct observations of events. Although verbal descriptions and observations are useful, many scientists prefer quantitative data for purposes of analysis.

When information is collected through a test, researchers try to ensure that the test is

* Valid: Measures what it purports to measure.
* Reliable: Provides consistent results when administered on different occasions.

To analyze data, scientists use mathematical procedures known as statistics to describe and draw inferences from data. Two types of statistics are most common:

* Inferential: used for making predictions about the population.
* Descriptive: used for describing the characteristics of the population and subjects. Scientists use both types of statistics to draw general conclusions about their population and sample.

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Developmental psychology is a subfield within psychology which focuses on the study of age-based behavioral changes. Historically, the term has been used specifically to refer to the behavioral development of children, but developmental psychologists actually study people of all ages, looking at behavior from the womb until death. Researchers in this field can apply their skills to the treatment of children with psychological disorders, the analysis of psychological issues which pertain to criminal cases, education, elder care, and a number of other situations.

Researchers in this field primarily gather evidence through observation, with each study adding to the overall body of material in developmental psychology. Experimentation under controlled circumstances may be used by some researchers, but most focus on watching humans in natural environments and learning about the ways in which development can be influenced or altered. Since many experiments involving the manipulation of environment could involve unethical methods such as subjecting children to sensory deprivation or malnourishing infants to determine the role of diet in infant development, observation is often the only way to gather data.

Developmental psychologists are interested in the emotional, intellectual, and moral development of people throughout their lifespan, looking at everything from the age infants first respond to specific stimuli to the behavioral changes which occur in the elderly. Developmental psychology is also concerned with physical and social development, such as the age at which boys and girls start differentiating between each other, or the dynamics of middle aged adults. They also study humans in the womb, especially in the later phases of pregnancy when the fetus appears to be engaging in conscious actions.

The study of developmental psychology is critical to understanding how humans mature, and to identifying issues with human maturation. Developmental psychologists, for example, can set basic milestones which can be used to determine whether or not a child is developing normally. Lagging behind normal development or failing to meet development targets by a specific age can be an early sign that a child is experiencing problems which need to be addressed.

Research in developmental psychology can also be used to explore the developmental differences between different populations, and the reasons why some groups seem to develop more quickly than others. This research can be valuable when people are deciding how to allocate funding and which social and educational issues need the most attention, as developmental psychology has illustrated that people need sound developmental building blocks to grow into healthy, well-adjusted adults.

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Developmental psychologists study how characteristics and behaviors first appear and how and when they change. They study the relationships between different types of development, such as cognitive and social, as well as individual variations in development, both normal and deviant. Initially, developmental psychology focused on childhood but was subsequently expanded to cover changes that occur over the entire life span, from the intrauterine environment through childhood, adolescence, middle age, and maturity. Three processes that play a central role in development are growth, maturation, and learning. Growth refers to physical changes that are quantitative, such as increases in height or weight. Maturation involves anatomical, neurophysiological, and chemical transformations that change the way a person functions (such as a woman’s passage into or out of childbearing age). Learning involves relatively long-term changes in behavior or performance acquired through observation, experience, or training.

One of the oldest questions in developmental psychology involves the nature-nurture controversy, which asks how and to what degree nature (inherited or genetic factors influencing development) contributes to a person’s biological, emotional, cognitive, and social development, and to what degree it is the result of nurture (the influence of learning and experience in the environment). This issue has been debated for centuries by philosophers, who often argued strenuously for the predominance of one influence over the other (a famous example is the British philosopher John Locke’s concept of the newborn human being as a blank slate, or tabula rasa , to be formed by experience). Pioneered by the American psychologist Arnold Gesell, the concept of maturation, which is central to developmental psychology, stresses the role of nature in human development. Gesell observed that the motor skills of children develop in a fixed order through a series of stages relatively unaffected by outside influences. The interplay of nature and nurture, rather than the importance of one over the other, however, has gained a greater emphasis in the work of more recent figures, notably the Swiss psychologist Jean Piaget, whose theory of cognitive development in children has been a model for much subsequent work in the field. Going beyond simplistic dichotomies, scientists have been able to gather substantial amounts of specific data on the effects of heredity and environment through family, twin, and adoption studies. Current concepts of maturation focus on models in which each stage of a developmental process is defined not only by innate characteristics but also by increased receptivity (or “readiness”) toward certain environmental factors.

Another significant issue in the field of developmental psychology is the question of continuity versus stages, specifically, does an individual’s development occur in a gradual and progressive (continuous) fashion, or in a distinct series of discrete stages? In his pioneering theory of cognitive development, Piaget delineated a sequence of developmental stages that occur in a fixed order with each dependent on the previous ones (sensorimotor, preoperational, concrete operational, and formal operational). Subsequent research has challenged some of his assumptions, finding in some cases that children are capable of advanced thinking at younger ages than those posited by Piaget. Observations such as these have led to the conclusion that cognitive development is more uneven and less systematic than previously thought, and that children’s reasoning abilities in a specific situation may depend on variables-familiarity with certain objects, language comprehension, and prior experiences-that are not part of Piaget’s system. One recent model advances the notion of cognitive development in “pockets” rather than globally uniform levels or stages. Another alternative that has been suggested is an information processing model focusing on gradual quantitative advances in memory and other learning abilities rather than qualitative progress through a series of stages.

In addition to Piaget, another major influence in the area of human development was Erik Erikson, whose eight stages of psychosocial development, encompassing the entire life span from infancy through old age, inspired an interest in the continuation of development past childhood. Erikson’s work also popularized the concept of the adolescent “identity crisis” (a term he coined). Yet another type of development that has gained increased interest in recent years is moral development, which has been most extensively investigated by Lawrence Kohlberg. Presenting subjects with hypothetical moral dilemmas, Kohlberg found that moral reasoning in children develops through three distinct levels (consisting of two stages each) between the age of seven and adolescence. Like Piaget’s theory, Kohlberg’s stages do not necessarily occur at a given age but they do occur consistently in a given order. Also, not all individuals reach the final stage, at which following rules and obeying the social order is superseded by the imperative of the individual conscience to obey ethical principles that may transcend the law. The universality of some of Kohlberg’s findings has been challenged in terms of applicability to non-Western cultures and women (Kohlberg’s research focused on men). When Carol Gilligan questioned subjects about moral conflicts, the reactions of male and female respondents differed significantly, and Gilligan drew up her own model for women.

* Anderson, Clifford. The Stages of Life: A Groundbreaking Discovery: the Steps to Psychological Maturity. New York: Atlantic Monthly Press, 1995.
* Berger, Kathleen Stassen. The Developing Person Through the Life Span. 2nd ed. New York: Worth Publishers, 1988.
* Cicchetti, Dante, and Donald J. Cohen, eds. Developmental Psychopathology. New York: J. Wiley, 1995.

“Developmental psychology”. Encyclopedia of Psychology. FindArticles.com. 09 Feb, 2010. http://findarticles.com/p/articles/mi_g2699/is_0000/ai_2699000095/
Gale Encyclopedia of Psychology, 2nd ed. Gale Group, 2001.