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Wechsler Adult Intelligence Scale
 
 
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Wechsler Adult Intelligence Scale (WAIS) is a general test of intelligence (IQ
Intelligence quotient

An Intelligence Quotient or IQ is a score derived from one of several different standardized tests attempting to measure intelligence. The term "IQ," a calque of the German language Intelligenz-Quotient, was coined by the German psychologist William Stern in 1912 as a proposed method of scoring early modern children's intelligenc...
), published in February 1955 as a revision of the Wechsler
David Wechsler

David "Wex" Wechsler was a leading United States psychologist. He developed well-known intelligence scales, such as the Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children ....
-Bellevue
Bellevue Hospital Center

Bellevue Hospital Center, founded in 1736, is the oldest public hospital in the United States. It is located in New York City and has been the site of countless milestones in the history of medicine....
 test (1939), a battery of tests that is composed from subtests Wechsler "adopted" from the Army Tests
Army

An army , in the broadest sense, is the land-based armed forces of a nation. It may also include other branches of the military such as an air force....
 (Yerkes
Robert Yerkes

Robert Mearns Yerkes was an United States psychologist, ethologist, and Primatology best known for his work in intelligence testing and in the field of comparative psychology....
, 1921). Wechsler
David Wechsler

David "Wex" Wechsler was a leading United States psychologist. He developed well-known intelligence scales, such as the Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children ....
 defined intelligence as "The global capacity of a person to act purposefully, to think rationally, and to deal effectively with his/her environment." The fourth edition of the test was released in 2008 by Pearson.

full scale IQ test is broken down into 15 sub tests, comprising the verbal (seven sub tests) and performance scales (seven sub tests).

Wechsler's tests provide six scores:
  1. a Verbal Comprehension Index (VCI)
  2. a Perceptual Reasoning Index (PRI)
  3. a Working Memory Index (WMI)
  4. a Processing Speed Index (PSI)
  5. a composite, single full-scale IQ (FSIQ) score based on the combined scores
  6. a General Ability Index (GAI) to identify general cognitive ability


WAIS-R was standardised in 1981 on a sample of 1,880 US subjects, ranging from 16 to 89 years of age, broken down into 9 different age groups.






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Wechsler Adult Intelligence Scale (WAIS) is a general test of intelligence (IQ
Intelligence quotient

An Intelligence Quotient or IQ is a score derived from one of several different standardized tests attempting to measure intelligence. The term "IQ," a calque of the German language Intelligenz-Quotient, was coined by the German psychologist William Stern in 1912 as a proposed method of scoring early modern children's intelligenc...
), published in February 1955 as a revision of the Wechsler
David Wechsler

David "Wex" Wechsler was a leading United States psychologist. He developed well-known intelligence scales, such as the Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children ....
-Bellevue
Bellevue Hospital Center

Bellevue Hospital Center, founded in 1736, is the oldest public hospital in the United States. It is located in New York City and has been the site of countless milestones in the history of medicine....
 test (1939), a battery of tests that is composed from subtests Wechsler "adopted" from the Army Tests
Army

An army , in the broadest sense, is the land-based armed forces of a nation. It may also include other branches of the military such as an air force....
 (Yerkes
Robert Yerkes

Robert Mearns Yerkes was an United States psychologist, ethologist, and Primatology best known for his work in intelligence testing and in the field of comparative psychology....
, 1921). Wechsler
David Wechsler

David "Wex" Wechsler was a leading United States psychologist. He developed well-known intelligence scales, such as the Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children ....
 defined intelligence as "The global capacity of a person to act purposefully, to think rationally, and to deal effectively with his/her environment." The fourth edition of the test was released in 2008 by Pearson.

Overview

The full scale IQ test is broken down into 15 sub tests, comprising the verbal (seven sub tests) and performance scales (seven sub tests).

Wechsler's tests provide six scores:
  1. a Verbal Comprehension Index (VCI)
  2. a Perceptual Reasoning Index (PRI)
  3. a Working Memory Index (WMI)
  4. a Processing Speed Index (PSI)
  5. a composite, single full-scale IQ (FSIQ) score based on the combined scores
  6. a General Ability Index (GAI) to identify general cognitive ability


WAIS-R was standardised in 1981 on a sample of 1,880 US subjects, ranging from 16 to 89 years of age, broken down into 9 different age groups. The current version is WAIS-IV (2008). 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
Median

In probability theory and statistics, a median is described as the number separating the higher half of a sample, a population, or a probability distribution, from the lower half....
 full-scale IQ is centered at 100, with a standard deviation
Standard deviation

In statistics, standard deviation is a simple measure of the variability or statistical dispersion of a data set. A low standard deviation indicates that all of the data points are very close to the same value , while high standard deviation indicates that the data are ?spread out? over a large range of values....
 of 15. In a normal distribution
Normal distribution

The normal distribution, also called the Gaussian distribution, is an important family of continuous probability distributions, applicable in many fields....
 this IQ range (1s above and below the mean - that is, between 85 and 115) is where approximately 68% of adults would fall.

Test variants

The WAIS-IV measure is appropriate throughout adulthood and for use with those individuals ages 16-90:11 years of age (this is an expanded age range for adults 74-90, reflecting the increased average life expectancy). For persons under 16, the Wechsler Intelligence Scale for Children (WISC
Wechsler Intelligence Scale for Children

The Wechsler Intelligence Scale for Children , developed by David Wechsler, is an intelligence test for children between the ages of 6 and 16 inclusive that can be completed without reading or writing....
, 6-16 yrs) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI
Wechsler Preschool and Primary Scale of Intelligence

The Wechsler Preschool and Primary Scale of Intelligence is an intelligence test designed for children ages 2 years 6 months to 7 years 3 months developed by David Wechsler in 1967....
, 2 1/2-7yrs, 3mos) are used.

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 a shorter amount of time. The Wechsler Abbreviated Scale of Intelligence (WASI) uses vocabulary, similarities, block design
Block design test

Block design is a subtest on many intelligence tests that tests visuospatial and motor skills. The testee is required to take blocks that have all white sides, all red sides, and red and white sides and arrange them according to a pattern....
 and matrix reasoning subtests similar to those of the WAIS to provide an estimate of full scale IQ in about 30 minutes.

Intelligence tests also are used in populations with psychiatric illness or brain injury, though some regard this use as controversial. Some neuropsychologists use the technique on people suffering brain damage as it leads to links
Mixed receptive-expressive language disorder

Mixed receptive-expressive language disorder is a communication disorder in which both the receptive and expressive areas of communication may be affected in any degree, from mild to severe....
 with which part of the brain has been affected, or use specific subtests in order to get an idea of the extent of the brain 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 .

15 subtests of the WAIS-IV


Verbal Comprehension Index

Information : Degree of general information acquired from culture
Culture

Culture is difficult to define. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions....
 (e.g. Who is the president of Russia?) Comprehension: Ability to deal with abstract social conventions, rules and expressions (e.g. What does "Kill 2 birds with 1 stone" metaphorically mean?) Similarities: Abstract verbal reasoning (e.g. In what way are an apple and a pear alike?) Vocabulary: The degree to which one has learned, been able to comprehend and verbally express vocabulary (e.g. What is a guitar?)

Working Memory Index

Digit span: attention/concentration (e.g. given the sequence of digits '123', reverse the sequence.) Letter-Number Sequencing: attention and working memory (e.g. Given Q1B3J2, place the numbers in numerical order and then the letters in alphabetical order) Arithmetic: Concentration while manipulating mental mathematical problems (e.g. How many 45c. stamps can you buy for a dollar?)

Perceptual Reasoning Index

Picture Completion: Ability to quickly perceive visual details Block Design
Block design test

Block design is a subtest on many intelligence tests that tests visuospatial and motor skills. The testee is required to take blocks that have all white sides, all red sides, and red and white sides and arrange them according to a pattern....
: Spatial perception, visual abstract processing & problem solving Matrix Reasoning: Nonverbal abstract problem solving, inductive reasoning, spatial reasoning Visual Puzzles: non-verbal reasoning Figure Weights: quantitative and analogical reasoning

Processing Speed Index


Symbol Search: Visual perception, speed Coding: Visual-motor coordination, motor and mental speed Cancellation; visual-perceptual speed

WAIS-III subtests grouped according to indices

In addition to the Verbal and Performance IQ scores, the following four indices are derived.

Verbal IQ (VIQ)


Verbal comprehension index (VCI)
  • Information
    Information

    Information as a Conveyed concept has a diversity of meanings, from everyday usage to technical settings. Generally speaking, the concept of information is closely related to notions of constraint, communication, control system, data, form, instruction, knowledge, Meaning , stimulation, pattern, perception, and knowledge representation....
  • Similarities
  • Vocabulary
    Vocabulary

    A person's vocabulary is the set of words they are familiar with in a language. A vocabulary usually grows and evolves with age, and serves as a useful and fundamental tool for communication and learning....


Working memory index (WMI)
  • Arithmetic
    Arithmetic

    Arithmetic or arithmetics is the oldest and most elementary branch of mathematics, used by almost everyone, for tasks ranging from simple day-to-day counting to advanced science and business calculations....
  • Digit Span
  • Letter-Number Sequencing


Performance IQ (PIQ)


Perceptual organization index (POI)
  • Block Design
    Block design test

    Block design is a subtest on many intelligence tests that tests visuospatial and motor skills. The testee is required to take blocks that have all white sides, all red sides, and red and white sides and arrange them according to a pattern....
  • Matrix
    Matrix

    Matrix usually refers to:* Matrix , a mathematical object generally represented as an array of numbers;* The Matrix , a series of films, video games and comic books;...
     Reasoning
  • Picture Completion


Processing speed index (PSI)
  • Digit Symbol-Coding
  • Symbol Search
  • Picture Arrangement
  • Object Assembly


Note: Picture Arrangement, Comprehension, and Object Assembly do not contribute to the Index Scores

WAIS-IV Structure


With the new WAIS-IV, the verbal/performance subscales have been removed and they have been replaced by the index scores. The General Ability Index (GAI) is now 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.

See also

  • David Wechsler
    David Wechsler

    David "Wex" Wechsler was a leading United States psychologist. He developed well-known intelligence scales, such as the Wechsler Adult Intelligence Scale and the Wechsler Intelligence Scale for Children ....
  • IQ
  • Wechsler Intelligence Scale for Children (WISC)
    Wechsler Intelligence Scale for Children

    The Wechsler Intelligence Scale for Children , developed by David Wechsler, is an intelligence test for children between the ages of 6 and 16 inclusive that can be completed without reading or writing....
  • Wechsler Preschool and Primary Scale of Intelligence (WPPSI)
    Wechsler Preschool and Primary Scale of Intelligence

    The Wechsler Preschool and Primary Scale of Intelligence is an intelligence test designed for children ages 2 years 6 months to 7 years 3 months developed by David Wechsler in 1967....


External links

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