Standard scores are derived from a comparison of the individual raw score with the mean and standard deviation of the group scores. The mean, or arithmetic average, is determined by adding the scores and dividing by the total number of scores obtained. The standard deviation measures the variation of the scores around the mean. Standard scores are obtained by subtracting the mean from the raw score and then dividing by the standard deviation.

Tables of norms are included in test manuals to indicate the expected range of raw scores. Normative data are derived from studies in which the test has been administered to a large, representative group of people. The test manual should include a description of the sample of people used to establish norms, including age, sex, geographical location, and occupation. Norms based on a group of people whose major characteristics are markedly dissimilar from those of the person being tested do not provide a fair standard of comparison.

Validity. Interpretation of test scores ultimately involves predictions about a subject’s behavior in a specified situation. If a test is an accurate predictor, it is said to have good validity. Before validity can be demonstrated, a test must first yield consistent, reliable measurements. In addition to reliability, psychologists recognize three main types of validity.

A test has content validity if the sample of items in the test is representative of all the relevant items that might have been used. Words included in a spelling test, for example, should cover a wide range of difficulty.

Criterion-related validity refers to a test’s accuracy in specifying a future or concurrent outcome. For example, an art-aptitude test has predictive validity if high scores are achieved by those who later do well in art school. The concurrent validity of a new intelligence test may be demonstrated if its scores correlate closely with those of an already well-established test.

Construct validity is generally determined by investigating what psychological traits or qualities a test measures; that is, by demonstrating that certain patterns of human behavior account to some degree for performance on the test. A test measuring the trait “need for achievement,” for instance, might be shown to predict that high scorers work more independently, persist longer on problem-solving tasks, and do better in competitive situations than low scores.

Controversies. The major psychological testing controversies stem from two interrelated issues: technical shortcomings in test design and ethical problems in interpretation and application of results. Some technical weaknesses exist in all tests. Because of this, it is crucial that results be viewed as only one kind of information about any individual. Most criticisms of testing arise from the overvaluation of and inappropriate reliance on test results in making major life decisions. These criticisms have been particularly relevant in the case of intelligence testing. Psychologists generally agree that using tests to bar youngsters from educational opportunities, without careful consideration of past and present resources or motivation, is unethical. Because tests tend to draw on those skills associated with white, middle-class functioning, they may discriminate against disadvantaged and minority groups. As long as unequal learning opportunities exist, they will continue to be reflected in test results. In the U.S., therefore, some states have established laws that carefully define the use of tests in public schools and agencies. The American Psychological Association, meanwhile, continues to work actively to monitor and refine ethical standards and public policy recommendations regarding the use of psychological testing.

8. Development psychology

Developmental Psychology study of behavioral changes and continuity from infancy to old age. Much emphasis in psychology has been given to the child and to the deviant personality. Developmental psychology is particularly significant, then, in that it provides for formal study of children and adults at every stage of development through the life span.

Developmental psychology reflects the view that human development and behavior throughout the life span is a function of the interaction between biologically determined factors, such as height or temperament, and environmental influences, such as family, schooling, religion, and culture. Studies of these interactions focus on their consequences for people at different age levels. For example, developmental psychologists are interested in how children who were physically abused by their parents behave when they themselves become parents. Studies, although inconclusive, suggest that abused children often become abusive parents.

Other recent studies have focused on the relationship between the aging process and intellectual competence; contrary to the traditional notion that a person’s intellectual skills decline rapidly after the age of 55, research indicates that the decline is gradual. American studies of adulthood, building on the work of Erik Erikson, point to stable periods with a duration of 5 to 7 years, during which energy is expended on career, family,