Wechsler Adult Intelligence Scale
Overview
The Wechsler Adult Intelligence Scale (WAIS) is a standardized test designed to measure various aspects of human intelligence. It was first published in 1955 by psychologist David Wechsler, and has since been updated several times, with the most recent version being the WAIS-IV, released in 2008. The WAIS is one of the most widely used intelligence tests in the world, and has been translated into multiple languages.
History
The WAIS was originally developed as a revision of the Wechsler-Bellevue Intelligence Scale, which was itself a revision of the earlier Army Alpha and Army Beta tests used by the U.S. military during World War I. The original WAIS (now referred to as the WAIS-I) was followed by the WAIS-R (Revised) in 1981, the WAIS-III in 1997, and the WAIS-IV in 2008. Each revision has included updates to the test items and scoring procedures to reflect advances in our understanding of human intelligence and changes in the population.
Structure
The WAIS-IV, like its predecessors, is divided into two main sections: the Verbal Comprehension Index (VCI) and the Perceptual Reasoning Index (PRI). Each of these sections is further divided into several subtests, each designed to measure a specific aspect of cognitive functioning. The VCI includes subtests such as Vocabulary, Similarities, and Information, while the PRI includes subtests like Block Design, Matrix Reasoning, and Visual Puzzles. In addition to these two main indices, the WAIS-IV also includes two supplementary indices: the Working Memory Index (WMI) and the Processing Speed Index (PSI).
Scoring
Scoring on the WAIS-IV is based on a comparison of the test-taker's performance with that of a normative sample. Each subtest is scored separately, and these scores are then combined to create the four index scores (VCI, PRI, WMI, and PSI). These index scores are in turn combined to create a Full Scale IQ (FSIQ) score, which is intended to represent the test-taker's overall level of cognitive functioning. The FSIQ score is scaled to have a mean of 100 and a standard deviation of 15, with higher scores indicating higher levels of cognitive functioning.
Validity and Reliability
The WAIS-IV has been found to have good reliability and validity. Reliability refers to the consistency of the test results, and is typically assessed by looking at the test-retest reliability (the correlation between scores on two administrations of the test) and the internal consistency (the correlation between scores on different subtests). Validity refers to the extent to which the test measures what it is intended to measure, and is typically assessed by looking at the correlation between WAIS-IV scores and scores on other measures of cognitive functioning.
Criticisms
While the WAIS-IV is widely used and generally well-regarded, it has also been subject to a number of criticisms. Some critics argue that the test is biased towards certain cultural and socioeconomic groups, and that it does not adequately measure all aspects of intelligence. Others have raised concerns about the use of the FSIQ score as a single measure of cognitive functioning, arguing that this oversimplifies the complex nature of human intelligence.