What are the Wechsler Adult Intelligence Scales?

The Wechsler Adult Intelligence Scales (WAIS) are a set of tests that measure the adult intelligence quotient (IQ). First developed under a clinical setting by psychologist David Weschler, the tests focus on an individual's capacity to rationally and effectively approach a problem. Weschler first devised them as a replacement to the Wechsler-Bellevue Intelligence Scale (WBIS).

Well-known for creating innovative intelligence scales, David Weschler originally crafted the WBIS in 1939. The later updates, the Wechsler Adult Intelligence Scales and the Wechsler Intelligence Scale for Children, are based on the early version of the test. Weschler's initial reasons for developing a new intelligence scale stemmed from a desire to evaluate his Bellvue patients and his dissatisfaction with the Stanford-Binet IQ test, which focused more on narrow, specific skills.

In conceiving the WBIS and the WAIS, Weschler introduced a new philosophy on the appraisal of adult intelligence that had evolved from a broader approach to intelligence. In effect, he believed that intelligence was a reflection of an individual's overall personality and its influence on the person's ability to purposefully, effectively and rationally approach the environment and its complexities.

The clinical standard for modern intelligence tests, the Wechsler Adult Intelligence Scales are also the most widely administered measurements of adult intelligence. There have been four revisions to the test since its inception, including the WAIS-R in 1981, the WAIS-III in 1998, and the WAIS-IV in 2008. All subsequent versions have been based on Wechsler's intelligence principles, with changes made to the norms, scores, indices and tests that are used to compile a complete intelligence scale.

The most recent version saw changes to previously established methods of compiling verbal and performance tests and scales. The WAIS-IV consists of 10 subtests that measure verbal comprehension, perceptual reasoning, working memory, and processing speed, with specific subtests comprising each category. Four index scores based on the subtest results from each of the verbal and performance categories can then be gathered. A measure of general intelligence is also provided from a collective analysis of the 10 subtests, the results of which determine the full scale IQ. A more narrow general ability index can be established from the verbal comprehension index and the perceptual reasoning index.

Individuals between the ages of 16 and 90 may take the Wechsler Adult Intelligence Scales. The WAIS-IV is used in a number of situations, including when assessing cognitive function in individuals affected by psychiatric illness or brain damage. While the test was created with non-brain damaged people in mind, neuropsychologists may apply it to brain damaged patients in order to identify the injured portions of the brain or determine the specific scores of damaged and undamaged areas.