Wechsler Adult Intelligence Scale
The Wechsler Adult Intelligence Scale (WAIS) is an IQ test designed to measure intelligence and cognitive ability in adults and older adolescents.[1]
The original WAIS (Form I) was published in February 1955 by David Wechsler and Chief Psychologist at Bellevue Hospital (1932–1967) in NYC as a revision of the Wechsler–Bellevue Intelligence Scale, released in 1939.[2] It is currently in its fourth edition (WAIS-IV) released in 2008 by Pearson, with the fifth edition (WAIS-5) set to release in fall of 2024, and is the most widely used IQ test, for both adults and older adolescents, in the world.[3][4]
The WAIS was founded to get to know Wechsler's patients at Bellevue Hospital and on his definition of intelligence, which he defined as "... the global capacity of a person to act purposefully, to think rationally, and to deal effectively with his environment."[5] He believed that intelligence was made up of specific elements that could be isolated, defined, and subsequently measured. However, these individual elements were not entirely independent, but were all interrelated. His argument, in other words, is that general intelligence is composed of various specific and interrelated functions or elements that can be individually measured.[6]
This theory differed greatly from the Binet scale which, in Wechsler's day, was generally considered the supreme authority with regard to intelligence testing. A drastically revised new version of the Binet scale, released in 1937, received a great deal of criticism from David Wechsler (after whom the original Wechsler–Bellevue Intelligence scale and the modern Wechsler Adult Intelligence Scale IV are named).[6]
These criticisms of the 1937 Binet test helped produce the Wechsler–Bellevue scale, released in 1939. However, the present-day WAIS-IV has contradicted many of these criticisms, by incorporating a single overall score, using multiple timed tasks, focusing on intellective items and other ways. While this scale has been revised (resulting in the present day WAIS-IV), many of the original concepts Wechsler argued for have become standards in psychological testing, including the point-scale concept and the performance-scale concept.[6]
WAIS[edit]
The WAIS was initially created as a revision of the Wechsler–Bellevue Intelligence Scale (WBIS), which was a battery of tests published by Wechsler in 1939. The WBIS was composed of subtests that could be found in various other intelligence tests of the time, such as Robert Yerkes' army testing program and the Binet-Simon scale. The WAIS was first released in February 1955 by David Wechsler. Because the Wechsler tests included non-verbal items (known as performance scales) as well as verbal items for all test-takers, and because the 1960 form of Lewis Terman's Stanford–Binet Intelligence Scales was less carefully developed than previous versions, Form I of the WAIS surpassed the Stanford–Binet tests in popularity by the 1960s.[2]
WAIS-R[edit]
The WAIS-R, a revised form of the WAIS, was released in 1981 and consisted of six verbal and five performance subtests. The verbal tests were: Information, Comprehension, Arithmetic, Digit Span, Similarities, and Vocabulary. The Performance subtests were: Picture Arrangement, Picture Completion, Block Design, Object Assembly, and Digit Symbol. A verbal IQ, performance IQ and full scale IQ were obtained.[11]
This revised edition did not provide new validity data, but used the data from the original WAIS; however new norms were provided, carefully stratified.[11]
WAIS-5[edit]
The fifth edition of the Wechsler Adult Intelligence Scale is slated to be released in late 2024. Normative data were collected in 2023–24 on a U.S. Census-reflective sample that was conormed on the Wechsler Memory Scale: Fifth Edition.
The WAIS-5 introduces several new subtests, particularly in the working memory domain, with Digit Span Sequencing and Running Digits now being the core subtests that compose the Working Memory Index. Digit Span Forward, Digit Span Backward, and Letter-Number Sequencing may also be used to construct the Expanded Working Memory Index.
The Perceptual Reasoning Index has been split into Visual Spatial Ability (Block Design, Visual Puzzles) and Fluid Reasoning (Matrix Reasoning, Figure Weights). A complementary Fluid Reasoning subtest Set Relations was also introduced, as well as an additional Processing Speed subtest Naming Speed Quantity, which was originally featured in the WISC-V.
The Full Scale Intelligence Quotient is now generated from only seven subtests (Similarities, Vocabulary, Block Design, Matrix Reasoning, Fluid Reasoning, Digit Span Sequencing, Coding), similar to the WISC-V. Fifteen ancillary index scores, including the General Ability Index, are also present.
Administration is anticipated to be shorter than the WAIS-IV, especially for those who are suspected as being intellectually gifted. The test may be administered in the classic physical format or on a digital platform.[14]
Age range and uses[edit]
The WAIS-IV measure is acceptable for use with people who are 16–90 years of age. For people younger than 16, the Wechsler Preschool and Primary Scale of Intelligence (WPPSI, 2½–7 years, 7 months) and the Wechsler Intelligence Scale for Children (WISC, 6–16 years) are used.[15]
Intelligence tests may be used to assess the level of cognitive functioning in individuals with psychiatric illness or brain injury. Rehabilitation psychologists and neuropsychologists use neuropsychological tests (including the WAIS-IV) to assess how the individual's brain is functioning after it has been injured. Specific subtests can provide insight into specific cognitive functions; for example, the digit span subtest could be used to look for attentional difficulties.[15]
The Wechsler tests can also be used to identify intellectual giftedness, and are commonly accepted as qualifying evidence for high-IQ societies, such as Mensa, Intertel and the Triple Nine Society.[16][17][18]