David Wechsler

David Wechsler (January 12th 1896, Lespezi, Romania - May 2nd 1981, New York) was a Psychologue. He developed three tests of Intelligence standardized usually used in North America: the Wechsler-Bellevue Intelligence Scale (WBIS), the Wechsler Adult Intelligence Scale (wais) and the Wechsler Intelligence Scale for Children (WISC).

It estimated that the intelligence is not only one thing, but well the mixture of several human features, each one measurable separately. For example, the results calculated by the wais measure verbal comprehension, space perception and the capacity to abstract the distractions.

Biography

He studied with the City College of New York, then with the Université of Columbia, where he obtained a control in 1917 and one doctorate in 1925 pennies the control of Robert S. Woodworth.

The army of the the United States engages it as psychologist with the camp Logan (Texas) in 1917. To perfect its formation, it sends it to study with the Université of London. It will work there with the psychologist Charles Spearman and the Mathématicien Karl Pearson.

From 1922 to 1925, he is clinical psychologist with the Bureau off Child Guidance (New York). He will occupy a post of secretary to the Psychological Corporation of 1925 to 1927. By afterwards, it still occupies a post of clinical psychologist of 1927 to 1932. He works then for the Psychiatric hospital Bellevue with New York. He will be psychologist as a chief there during 35 years, that is to say of 1932 to 1967. He also taught of 1933 to 1967, as a clinical professor, with the medical Board of the Université of New York.

Work

During the First World War, it helped Edwin Garrigues Boring (1886-1968) to evaluate the recruits of the army using the Test Alpha. It was conceived to measure the skill of future soldiers having a very different experiment, and to determine which military employment would suit them best. Its observations on the weaknesses of the Alpha test led it to conclude that the academic definition of the intelligence was not applicable to the everyday life.

It became aware that an adequate definition of the intelligence was to be broader and to be valid according to observable criteria. He regarded the theory G and S of Spearman as too simplistic. He saw the intelligence as a consequence more than as a cause.

In 1938, it develops a battery of test of intelligence known under the name of Wechsler-Bellevue Intelligence Scale (WBIS). In an original manner, these tests were conceived to measure the intelligence of the adults from the clinical point of view. Wechsler rejected the concept of age of reference, which was usually used for to measure the human intelligence. It defined the intelligence as a capacity, total, to act according to an intention, to think rationally and to act indeed on its environment. This vision contains the idea that the intelligence is not a single capacity, but well an aggregate of several human features. For him, the normal intelligence is a median value for the members of a definite group. On a standardized scale, the median value, established to 100 per convention, should represent the average of this group.

The choice of an average of 100 and of a standard deviation of 15 makes it possible to obtain results close to those obtained with the tests of William Stern (mental age) for average IQ (effect of compressing upwards).

The WBIS, re-examined in 1942 by Wechsler, became soon the test more used in the United States. It published the Wechsler Intelligence Scale for Children (WISC) in 1949 (re-examined in 1974). In 1955, it develops another test of intelligence for the adults, the Wechsler Adult Intelligence Scale (wais), which borrows the same structure as the WBIS, but standardized to take account of various groups in the population. It includes 10 people of origin or descent other than European, that with an aim of reflecting the complete population. It will be re-examined in 1981, a little before the death of Wechsler. Its last test of intelligence, the Wechsler Preschool and Primary Scale off Intelligence (WPPSI), is published in 1967. It is an adaptation of the WISC for the children of very low age.

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