Special fields of psychology — страница 9

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personal feelings or characteristics that are too painful to acknowledge. Because projective techniques are relatively unstructured and offer minimal cues to aid in defining responses, they tend to elicit concerns that are highly personal and significant. The best-known projective tests are the Rorschach test, popularly known as the inkblot test, and the Thematic Apperception Test; others include word-association techniques, sentence-completion tests, and various drawing procedures. The psychologist’s past experience provides the framework for evaluating individual responses. Although the subjective nature of interpretation makes these tests particularly vulnerable to criticism, in clinical settings they are part of the standard battery of psychological tests. Interpretation of

Results The most important aspect of psychological testing involves the interpretation of test results. Scoring. The raw score is the simple numerical count of responses, such as the number of correct answers on an intelligence test. The usefulness of the raw score is limited, however, because it does not convey how well someone does in comparison with others taking the same test. Percentile scores, standard scores, and norms are all devices for making this comparison. Percentile scoring expresses the rank order of the scores in percentages. The percentile level of a person’s score indicates the proportion of the group that scored above and below that individual. When a score falls at the 50th percentile, for example, half of the group scored higher and half scored lower; a

score at the 80th percentile indicates that 20 percent scored higher and 80 percent scored lower than the person being evaluated. 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