David Wechsler

David Wechsler (January 12, 1896 - May 2, 1981) was a leading American psychologist. He developed well-known intelligence scales, such as the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC). Wechsler is also known for establishing the deviation quotient, or DQ, which replaced the use of mental ages in testing an individual’s IQ. A student of both Karl Pearson and Charles Spearman, Wechsler was also greatly influenced by the psychologist E.L. Thorndike. Updated versions of Wechsler’s intelligence tests continue to remain significantly popular in the twenty-first century.

Life

Wechsler was born into a Jewish family in Lespezi, Romania, and immigrated with his parents to the United States as a child. He studied at the City College of New York and Columbia University, where he earned his master's degree in 1917. Shortly after the U.S. entered the First World War, Wechsler joined the U.S. Army as an army psychologist to aid in the screening of new draftees. Assigned to Camp Logan, Texas, Wechsler worked alongside prominent intelligence theorists Karl Pearson, Charles Spearman, Edward Thorndike, and Robert Mearns Yerkes. Here Wechsler scored the Army Alpha Test, one of two tests designed by the U.S. Army to test group intelligence. Following his work with the Alpha Test, Wechsler worked as an individual psychological examiner, administering the Stanford-Binet test to recruits who had performed poorly in the group intelligence testing. In 1918 Wechsler, along with Spearman and Pearson were sent to perform similar research at the University of London.

Following World War I, Wechsler studied at the University of Paris where he undertook extensive research in experimental psychology until 1922. Upon returning to the United States, Wechsler worked as a clinical psychologist at the Bureau of Child Guidance in New York. In 1925 he received a Ph.D. in experimental psychology from Columbia University where he studied under the direction of Robert S. Woodworth. After short stints at various locations, including five years in private practice, Wechsler became chief psychologist at Bellevue Psychiatric Hospital in 1932. In 1939 Wechsler published The Measurement of Adult Intelligence, following in 1940 by the equally influential Non-intellective Factors in General Intelligence.

He remained at the Bellevue Psychiatric Hospital until 1967, later dying in 1981 at the age of 85.

Work

Intelligence Scales

While working at the Bellevue Psychiatric Hospital, Wechsler published various intelligence scales. The renowned Wechsler Adult Intelligence Scale (WAIS) was developed first in 1939 and termed the Wechsler-Bellevue Intelligence Test. From this he derived the Wechsler Intelligence Scale for Children (WISC) in 1949 and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) in 1967. Wechsler originally created these tests to find out more about his patients at the Bellevue clinic; he found the then-popular Stanford-Binet IQ test unsatisfactory. Wechsler’s tests were based on his philosophy that intelligence is "the global capacity to act purposefully, to think rationally, and to deal effectively with [one's] environment."

The Wechsler scales introduced many novel concepts and breakthroughs to the intelligence testing movement. First, he did away with the “quotient” scores of older intelligence tests, or the Q in "I.Q.". Instead, he assigned an arbitrary value of 100 to the mean intelligence and added or subtracted another 15 points for each standard deviation above or below the subject’s mean. Rejecting a concept of global intelligence, as propagated by Charles Spearman’s Spearman's hypothesis, he divided the concept of intelligence into two main areas: verbal and performance, and further subdivided and tested each area with a different subtest. These conceptualizations continue to be reflected in the Wechsler scales of the twenty-first century; as such, the WAIS continues to remain the most commonly administered psychological test in existence .

Intelligence Testing

The full scale IQ test is broken down into 14 sub tests, comprising the verbal scale, seven verbal sub tests, the performance scale and seven performance sub tests. Wechsler's tests provide three scores; a verbal IQ score, a performance IQ score, and a composite IQ score based on the combined scores.

The Wechsler Adult Intelligence Scale is appropriate throughout adulthood and for use with those individuals over 74 years of age. For testing children aged seven to 16, the Wechsler Intelligence Scale for Children is used, while the Wechsler Preschool and Primary Scale of Intelligence is used for testing children aged two and a half to seven. Both tests can be completed without reading or writing.

Verbal subtests aim to test general cultural information, abstract comprehension, arithmetic, verbal reasoning, vocabulary, concentration, and memory. Performance subtests include visual perception, visual-motor coordination, spatial perception, abstract problem solving, sequential reasoning, perception speed and visual analysis.

Other Uses

Wechsler’s intelligence scales are used not only as an intelligence test, but also as a clinical tool. Many practitioners use the Wechsler’s Intelligence Scale for Children (WISC) to diagnose attention-deficit hyperactivity disorder (ADHD) and to detect learning disabilities. This is usually done through a process called pattern analysis, in which the various subtests' scores are compared to one another and clusters of unusually low scores in relation to the others are searched for. David Wechsler himself suggested this in 1958 . The empirical consensus is that the WISC is best used as a tool to evaluate intelligence and not to diagnose ADHD or learning disabled children. However, many clinicians use it to compare a child's cognitive development to his or her actual school or social performance. Using this discrepancy and other sources of data, the WISC can contribute information concerning a child's psychological well-being.

Legacy

Wechsler is best known for his many contributions to intelligence theory. He is credited with the creation of various intelligence testing scales, including the renowned Wechsler-Bellevue Scale of Intelligence, the Wechsler Memory Scale, the Wechsler Intelligence Scale for Children, the Wechsler Adult Intelligence Scale, and the Wechsler Primary and Preschool Scale of Intelligence. Many of these tests have remained in circulation into the twenty-first century, most showing only small alteration over time. Wechsler is also known for his creation of the deviation quotient, or DQ, which worked to replace mental age in computing IQ scores; this allowed for greater comparison among adult examinees. An author of various influential publications, Wechsler viewed intelligence as an effect rather than a cause, and believed former assessments of general intelligence to be too narrow. Instead, he found that non-intellective factors, such as personality, often contribute to the development of an individual’s intelligence. When he died at the age of 85, Wechsler was a greatly respected psychologist.

Publications

• Wechsler, D. (1939). The Measurement of Adult Intelligence. Baltimore: Williams & Wilkins. ISBN 0548385300.
• Wechsler, D. (1940). Non-intellective Factors in General Intelligence. Psychological Bulletin, 37, 444-445.
• Wechsler, D.(1949). Manual for the Wechsler Intelligence Scale for Children. New York: The Psychological Corporation.
• Wechsler, D. (1955a). The Range of Human Capacities (2nd ed.). Baltimore: Williams & Wilkins.
• Wechsler, D. (1955b). Manual for the Wechsler Adult Intelligence Scale. New York: The Psychological Corporation.
• Wechsler, D. (1967). Manual for the Wechsler Preschool and Primary Scale of Intelligence. New York: Psychological Corporation.

References

ISBN links support NWE through referral fees

• Kaplan, R.M. & Saccuzzo, D.P. (2005). Psychological Testing: Principles, Applications, and Issues. Belmont, CA: Thomson Wadsworth. ISBN 0534633064.
• Plucker, J. A. (Ed.). (2003). Human Intelligence: Historical Influences, Current Controversies, Teaching Resources. Retrieved 1 November, 2007.
• Edwards, A. J. (1994). Wechsler, David (1896-1981). In R. J. Sternberg (Ed.), Encyclopedia of Intelligence (Vol. 1, pp. 1134-1136). New York: Macmillan. ISBN 0028974077.
• Fancher, R. E. (1985). The Intelligence Men: Makers of the IQ Controversy. New York: W. W. Norton & Company. ISBN 0393955257.

External Links

• WISC at Farleigh Dickinson University
• WISC-IV Harcourt Assessment
• Overview
• Individual tests

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