Psychological Testing: Wechsler Adult Intelligence Scale (WAIS)

Erin L. George, MFT
Erin L. George, MFT
Medical editor

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What is the Wechsler Adult Intelligence Scale?

The Wechsler Adult Intelligence Scale (WAIS) is a widely used intelligence test designed to assess the cognitive abilities of adults. Developed by David Wechsler, the scale provides a comprehensive measure of a person’s intellectual functioning, including verbal and nonverbal domains. Its primary use is in clinical, educational, and vocational settings to evaluate cognitive strengths and weaknesses, guide intervention strategies, and inform decision-making processes related to educational and career planning. 

Although the Wechsler Adult Intelligence Scale (WAIS) is an intelligence test, it is also used in clinical settings by psychologists and other mental health professionals to diagnose intellectual disabilities, identify cognitive impairments, and guide treatment planning. Psychologists may use it to assess cognitive functioning in people with neurological disorders, learning disabilities, or mental health disorders.


The comprehensive nature of WAIS allows providers to gain insights into a patient’s cognitive profile, helping to tailor interventions and support strategies to address specific cognitive challenges. Additionally, WAIS scores can inform educational and vocational decisions, aiding in the development of personalized plans to optimize an individual's cognitive strengths and mitigate limitations. 

Read on to learn more about WAIS, other versions of WAIS tests, their applications, and their significance.

What is the Wechsler Intelligence Scale?

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The Wechsler Adult Intelligence Scale serves as a comprehensive tool in psychological assessment, specifically designed to measure the intelligence of adults. The WAIS provides a nuanced understanding of cognitive abilities and intellectual functioning across various domains. It is employed in clinical, educational, and vocational settings to assess an individual's cognitive strengths and weaknesses, aiding in the diagnosis of intellectual disabilities, learning disorders, and cognitive impairments.

Erin L. George, MA-MFT, says, "The WAIS is a fantastic tool for helping direct support health staff and patients to identify learning disorders and ways people may alternatively process information. Identifying these alternative patterns of processing can be helpful in developing strategies to work around weaknesses and improve overall intellectual functioning. This can make a major difference in a person's life, helping them on a day-to-day basis and giving them confidence and, in some cases, the ability to achieve more independence."

The latest edition, WAIS-IV, includes updated components and subtests to provide a contemporary and accurate evaluation of a person’s cognitive profile.

The WAIS-IV assesses multiple types of intelligence through four primary indices:

  • The Verbal Comprehension Index (VCI)
  • The Perceptual Reasoning Index (PRI)
  • The Working Memory Index (WMI)
  • The Processing Speed Index (PSI)

These indices collectively offer insights into an individual's verbal abilities, perceptual reasoning skills, working memory capacity, and processing speed. The subtests within each index measure specific cognitive functions, such as vocabulary knowledge, spatial reasoning, arithmetic ability, and information processing speed. 

By evaluating these diverse facets of intelligence, the WAIS-IV provides a comprehensive and detailed portrait of an individual's cognitive profile, assisting clinicians, educators, and professionals in making informed decisions about diagnosis, intervention, and support. And these tests are always being improved upon—the WAIS-V will be coming out sometime in 2024. WAIS-IV critiques have suggested subtests were too lengthy to administer and that the lengthy format made the test more expensive than necessary. Version V will remedy this critique and be faster to administer.

Historical Context of WAIS and Development

The Wechsler Adult Intelligence Scale (WAIS) was developed in 1939 by David Wechsler as a revision to the Wechsler-Bellevue Intelligence Scale. One of the most significant milestones occurred in 1955 with the release of the WAIS-R, representing a major revision and standardization of the original scale. Subsequent versions, including the WAIS-III in 1997, introduced advancements in psychometric methodology and expanded the understanding of cognitive abilities. Advancements in the WAIS included the addition of testing areas, such as verbal comprehension, working memory, perceptual organization, and a person's ability to process information. These factors allowed a more comprehensive look at IQ and intellectual ability than tests administered prior to the WAIS with 14 subtests.

The evolution from the original WAIS to the latest version, WAIS-IV, highlights notable improvements in the assessment of intelligence.

The WAIS-IV, released in 2008, incorporates updated norms and a more modernized structure. It features a refined factor structure, revised subtests, and improved measurement of cognitive domains, providing a more accurate and comprehensive evaluation of an individual's intellectual abilities compared to its predecessors.

The ongoing revisions, including the forthcoming WAIS-V, underscore a commitment to staying current with advancements in psychological measurement and ensuring the WAIS remains a reliable and valid tool for assessing cognitive functioning.


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 WAIS was an improvement over prior Wechsler tests because it was able to be measured against other parallel tests available at the time. This helped to ensure the WAIS results' validity. 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.

What is WAIS?

WAIS stands for Wechsler Adult Intelligence Scale and is a widely used intelligence test for adults. It is designed to measure cognitive ability in several areas, such as vocabulary, comprehension, arithmetic, and reasoning skills. WAIS consists of several subtests that provide scores for different cognitive domains. These subtests assess an individual's ability to process information and their speed of processing. The test takes into account age and provides norms for comparison with individuals of the same age range. WAIS provides an overall score, as well as scores for specific cognitive domains, to give a comprehensive assessment of an individual's cognitive abilities. It is used in clinical and research settings as a tool for testing intelligence and cognitive functioning.

What Does the WAIS Test Measure?

The WAIS test is designed to measure the intelligence of adults and is considered one of the most widely used intelligence tests. Developed by David Wechsler, the test consists of subtests that assess different cognitive abilities, such as verbal comprehension, perceptual reasoning, working memory, and processing speed.

The test provides a standardized score based on the individual's performance, which can be used to assess intellectual abilities, educational needs, and cognitive strengths and weaknesses. The WAIS test is age-appropriate and is widely used in various settings such as clinical assessments, educational evaluations, and vocational settings. The results from the WAIS test can provide valuable information to help individuals reach their full potential.

Erin L. George, MA-MFT, says, "Results from the WAIS offer hope for increased personal autonomy in adults with significant intellectual challenges. I have seen this test used as a tool to structure a treatment plan that offered a young man a chance to live on his own, obtain employment, and manage everyday tasks. This man was able to move out of a group home and into an apartment on his own—something he'd been hoping to do for years. With the right support team and information garnered from the WAIS, adults with cognitive disabilities have a better chance of achieving their goals. Test results alone, however, are only the first step."


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.[5]

This revised edition did not provide new validity data but used the validity data from the original WAIS; however, new norms were provided and carefully stratified.[5]


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).

Verbal IQ (VIQ)

This included seven tests and provided two subindexes: verbal comprehension and working memory.

The verbal comprehension index included the following tests:

  • Information
  • Similarities
  • Vocabulary

The working memory index included:

  • Arithmetic
  • Digit span

Letter-number sequencing and comprehension are not included in these indices but are used as substitutions for spoiled subtests within the WMI and VCI, respectively.

Performance IQ (PIQ)

This included six tests and provided two subindexes: perceptual organization and processing speed.

The perceptual organization index included:

  • Block design
  • Matrix reasoning
  • Picture completion

The processing speed index included:

  • Digit symbol-coding
  • Symbol search

Two tests, picture arrangement and object assembly, were not included in the indexes. Object assembly is not included in the PIQ.


The current 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 comprising the full-scale IQ. 

With the new WAIS-IV, the verbal/performance subscales 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 impairment.

Indexes and Scales

There are four index scores representing major components of intelligence:

  • Verbal Comprehension Index (VCI)
  • Perceptual Reasoning Index (PRI)
  • Working Memory Index (WMI)
  • Processing Speed Index (PSI)

Two broad scores are also generated, which can be used to summarize general intellectual abilities:

  • Full-scale IQ (FSIQ), based on the total combined performance of the VCI, PRI, WMI, and PSI
  • General Ability Index (GAI), based only on the six subtests that comprise the VCI and PRI

Someone taking The Wechsler Adult Intelligence Scale (WAIS)

Supplemental Subtests

The Verbal Comprehension Index includes four tests:

  • Similarities: Abstract verbal reasoning (e.g., "In what way are an apple and a pear alike?")
  • Vocabulary: The degree to which one has learned and been able to comprehend and verbally express vocabulary (e.g., "What is a guitar?")
  • Information: Degree of general information acquired from culture (e.g., "Who is the president of Russia?")
  • Comprehension [Supplemental]: Ability to deal with abstract social conventions, rules, and expressions (e.g., "What does Kill two birds with one stone metaphorically mean?")

The Perceptual Reasoning Index comprises five tests

  • Block Design: Spatial perception, visual abstract processing, and problem solving
  • Matrix Reasoning: Nonverbal abstract problem-solving, inductive reasoning, and spatial reasoning
  • Visual Puzzles: Nonverbal reasoning
  • Picture Completion [Supplemental]: Ability to quickly perceive visual details
  • Figure Weights [Supplemental]: Quantitative and analogical reasoning

The Working Memory Index is a single score obtained from three tests

  • Digit span: Attention, concentration, mental control (e.g., Repeat the numbers 1-2-3 in reverse sequence)
  • Arithmetic: Concentration while manipulating mental mathematical problems (e.g., "How many 45-cent stamps can you buy for a dollar?")
  • Letter-Number Sequencing [Supplemental]: Attention and working memory (e.g., Repeat the sequence Q-1-B-3-J-2, but place the numbers in numerical order and then the letters in alphabetical order)

The Processing Speed Index includes three tests:

  • Symbol Search: Visual perception and speed
  • Coding: Visual-motor coordination and motor and mental speed
  • Cancellation [Supplemental]: Visual-perceptual speed


The WAIS-IV was standardized on a sample of 2,200 people in the United States ranging in age from 16 to 90. An extension of the standardization has been conducted with 688 Canadians in the same age range. The median full-scale IQ is centered at 100, with a standard deviation of 15.[6] In a normal distribution, the IQ range of one standard deviation above and below the mean (i.e., between 85 and 115) is where approximately 68% of all adults would fall.

Other Test Variants and Uses

The WAIS-IV measure is appropriate for use with individuals aged 16-90 years. For individuals under 16 years, the Wechsler Intelligence Scale for Children (WISC, 6-16 yrs) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI, 2 1/2-7yrs, 3 mos) are used. These younger versions are great for individualized education plans in schools (IEPs) and diagnosing learning disabilities, which can lead to early intervention opportunities for kids before school starts.

A short, four-subtest version of the WAIS-III battery has been released, allowing clinicians to form a validated estimate of verbal, performance, and full-scale IQ in older adolescents in a shorter amount of time. The Wechsler Abbreviated Scale of Intelligence (WASI) uses vocabulary, similarities, block design, and matrix reasoning subtests similar to those of the WAIS to provide an estimate of full-scale IQ in approximately 30 minutes.

Intelligence tests may also be utilized in populations with psychiatric illness or brain injury to assess the level of cognitive functioning, but some regard this use as controversial. Some neuropsychologists use the technique on people suffering from brain damage, as it links which part of the brain has been affected, or uses specific subtests to get an idea of the extent of the brain injury or damage. For example, digit span may be used to get a sense of attentional difficulties.

Others employ the  WAIS-R NI (Wechsler Adult Intelligence Scale-Revised as a Neuropsychological Instrument), another measure published by Harcourt. Each subtest score is tallied and calculated with respect to non-normal or brain-damaged norms. As the WAIS is developed for the average, non-injured individual, separate norms were developed for appropriate comparison among similar functioning individuals.

What Is Full-Scale IQ?

Full-scale IQ is a measure of intelligence derived from standardized IQ tests, such as the Wechsler Intelligence Scale for Children (WISC) or the Wechsler Adult Intelligence Scale (WAIS). It is a composite score based on an individual's performance across multiple sections or subtests of the IQ test. These subtests are designed to assess a wide variety of cognitive abilities, including knowledge, verbal comprehension, perceptual reasoning, working memory, and processing speed. The Full Scale IQ score provides an overall measure of an individual's cognitive abilities and is compared to an average score for people of the same age group. It is an important data point in assessing an individual's intellectual abilities.


  1. ^ Lichtenberger, Elizabeth O.; Kaufman, Alan S (2002). Assessing adolescent and adult intelligence. Boston: Allyn and Bacon. pp. 3. ISBN 020530527x. 
  2. ^ a b Lichtenberger, Elizabeth O.; Kaufman, Alan S (2002). Assessing adolescent and adult intelligence. Boston: Allyn and Bacon. pp. 7. ISBN 020530527x. 
  3. ^ Lichtenberger, Elizabeth O.; Kaufman, Alan S (2002). Assessing adolescent and adult intelligence. Boston: Allyn and Bacon. pp. 6. ISBN 020530527x. 
  4. ^ Wechsler, David (1939). The measurement of adult intelligence. Baltimore: Williams & Wilkins. p. 229. 
  5. ^ a b "Wechsler Adult Intelligence Scale--Revised". Retrieved 2009-03-31. 
  6. ^ "Distribution of IQ Scores". MSN Encarta. Retrieved 2007-07-08. [dead link] (no longer available)

  • Axelrod, BN; Ryan, JJ (2000). "Prorating Wechsler Adult Intelligence Scale-III summary scores". Journal of Clinical Psychology 56 (6): 807–11.  PubMed
  • Ryan, JJ; Schnakenberg-Ott, SD (2003). "Scoring reliability on the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III)". Assessment 10 (2): 151–9.  PubMed

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