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. For children between the ages of 6 and 16, Wechsler Intelligence Scale for Children (WISC) is commonly used.

The original WAIS (Form I) was published in February 1955 by David Wechsler, Chief Psychologist at Bellevue Hospital (1932–1967) in New York City, as a revision of the Wechsler–Bellevue Intelligence Scale released in 1939. It is currently in its fifth edition (WAIS-5), released in 2024 by Pearson. It is the most widely used IQ test, for both adults and older adolescents, in the world.

History

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." 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.

This theory differed greatly from the Binet-Simon Intelligence Test 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 subsequent Wechsler Scales are named).

used the point scale concept instead of the age scale, and
included a non-verbal performance scale.

Point scale concept

In the Binet scales (prior to the 1986 version) items were grouped according to age level. Each of these age levels was composed of a group of tasks that could be passed by two-thirds to three-quarters of the individuals in that level. This meant that items were not arranged according to content. Additionally, an individual taking a Binet test would only receive credit if a certain number of the tasks were completed. This meant that falling short just one task required for the credit, resulted in no credit at all (for example, if passing three out of four tasks was required to receive credit, then passing two yielded no credit). The result was a test that could be made up of different content areas (or subtests) with both an overall score and a score for each content area. In turn, this allowed for an analysis to be made of an individual's ability in a variety of content areas (as opposed to one general score).

WAIS-III

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The WAIS-III, a subsequent revision of the WAIS and the WAIS-R, was released in 1997. It provided scores for Verbal IQ, Performance IQ, and Full Scale IQ, along with four secondary indices (Verbal Comprehension, Working Memory, Perceptual Organization, and Processing Speed).

WAIS-IV

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The previous version of the test, the WAIS-IV, which was released in 2008, is composed of 10 core subtests and five supplemental subtests, with the 10 core subtests yielding scaled scores that sum to derive the Full Scale IQ. With the WAIS-IV, the verbal/performance IQ scores from previous versions were removed and replaced by the index scores. The General Ability Index (GAI) was included, which consists of the Similarities, Vocabulary and Information subtests from the Verbal Comprehension Index and the Block Design, Matrix Reasoning and Visual Puzzles subtests from the Perceptual Reasoning Index. The GAI is clinically useful because it can be used as a measure of cognitive abilities that are less vulnerable to impairments of processing speed and working memory. There are several notable features in this version of the intelligence scale that make it unique from previous versions. Some of these changes include the removal of Picture Arrangement, Object Assembly, Mazes, Verbal IQ, and Performance IQ and the addition of five subtests that emphasize fluid reasoning and/or working memory. The demographic characteristics of the sample were modeled after the proportions of different groups in an analysis of data from the U.S. Census Bureau. An extension of the standardization has been conducted with 688 Canadians in the same age range.

WAIS-5

The fifth edition of the Wechsler Adult Intelligence Scale was 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, Spatial Addition, Symbol Span, 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, Figure Weights, 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.

Age range and uses

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.

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.

WASI-II

The Wechsler Abbreviated Scale of Intelligence – 2nd edition (WASI-II) is a short psychological test that was developed in 2011 by Pearson to estimate intellectual functioning in a shorter period of time than the WAIS-IV. The WASI-II only has 4 subtests: Block Design, Vocabulary, Similarities, and Matrix Reasoning, compared to the 10 core subtests that are present in the WAIS-IV. These 4 subtests have the same structure as the similarly-named subtests on the WAIS-IV, but have different questions.

The WASI-II can derive 4 composite scores from a combination of the 4 subtests. A Verbal Comprehension Index (VCI) can be derived from the raw scores on the Vocabulary and Similarities subtests. A Perceptual Reasoning Index (PRI) can be derived from the raw scores on the Matrix Reasoning and Block Design subtests. A Full Scale IQ-2 (FSIQ-2) can be derived from the raw scores on the Matrix Reasoning and Vocabulary subtests, while a Full Scale IQ-4 (FSIQ-4) can be derived from the raw scores on all 4 subtests.

WASI-II Subtests grouped by index

{| class="wikitable"

!Index

!Subtest

!Description

!Proposed abilities measured

! rowspan="2" |Verbal Comprehension

|Similarities

|Describe how two words or concepts are similar.

|Abstract verbal reasoning; semantic knowledge

|Vocabulary

|Name objects in pictures or define words presented to them.

|Semantic knowledge; verbal comprehension and expression

! rowspan="2" |Perceptual Reasoning

|Block Design

|Put together red-and-white blocks in a pattern according to a displayed model. This is timed, and some of the more difficult puzzles award bonuses for speed.

|Visual spatial processing and problem solving; visual motor construction

|Matrix Reasoning

|View an array of pictures with one missing square, and select the picture that fits the array from five options.

|Nonverbal abstract problem solving, inductive reasoning

References

External links

FAQ/Finding Information About Psychological Tests (American Psychological Association)
Classics in the History of Psychology