Wechsler Adult Intelligence Scale
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Wechsler Adult Intelligence Scale or WAIS is a general test of intelligence (IQ), published in February 1955 as a revision of the Wechsler-Bellevue test (1939), standardised for use with adults over the age of 16.
Intelligence is quantified as the global capacity of the individual to act purposefully, to think rationally, and to deal effectively with the environment.
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[edit] Overview
The full scale IQ is broken down into 14 subtests, comprising the verbal (7 subtests) and performance scales (7 subtests).
Wechsler's tests provide three scores:
- a verbal IQ
- a performance IQ
- a composite, single full-scale IQ score based on the combined scores.
WAIS-R was standardised in 1981 on a sample of 1,880 US subjects, ranging from 16 to 74 years of age, broken down into 9 different age groups. It is considered to have very strong reliability. The current version is WAIS-III (1997).
The average full-scale IQ is 100, with a standard deviation of 15 (above and below the mean). This is the average IQ range where most adults would fall.
[edit] Test variants
The WAIS-III measure is appropriate throughout adulthood and for use with those individuals over 74 years of age. For persons under 16, the Wechsler Intelligence Scale for Children (WISC, 7-16 yrs) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI, 2 1/2-7 yrs) are used.
An IQ score can be obtained without administering the verbal section of the test since each section yields its own score.
Neuropsychologists use the technique on people suffering brain damage as it leads to links 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. However, this is usually done with a separate version of the WAIS, known as the WAIS-R NI (Wechsler Adult Intelligence Scale-Revised as a Neuropsychological Instrument). 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.
A short, four-subtest, version of the battery has recently 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 the vocabulary, similarities, block design and matrix reasoning subtests of the WAIS to provide an estimate of the full IQ scores.
[edit] 14 subtests of the WAIS-III
[edit] Verbal Subtests
- Information
- Degree of general information acquired from culture (e.g. Who is the premier of Victoria?)
- Comprehension
- Ability to deal with abstract social conventions, rules and expressions (e.g. What does - Kill 2 birds with 1 stone metaphorically mean?)
- Arithmetic
- Concentration while manipulating mental mathematical problems (e.g. How many 45c. stamps can you buy for a dollar?)
- Similarities/Differences
- Abstract verbal reasoning (e.g. In what way are an apple and a pear alike and/or unalike?)
- Vocabulary
- The degree to which one has learned, been able to comprehend and verbally express vocabulary (e.g. What is a guitar?)
- Digit span
- attention/concentration (e.g. Digits forward: 123, Digits backward 321.)
- Letter-Number Sequencing
- attention and working memory (e.g. Given Q1B3J2, place the numbers in numerical order and then the letters in alphabetical order)
[edit] Performance Subtests
- Picture Completion
- Ability to quickly perceive visual details
- Digit Symbol - Coding
- Visual-motor coordination, motor and mental speed
- Block Design
- Spatial perception, visual abstract processing & problem solving
- Matrix Reasoning
- Nonverbal abstract problem solving, inductive reasoning, spatial reasoning
- Picture Arrangement
- Logical/sequential reasoning, social insight
- Symbol Search
- Visual perception, speed
- Object Assembly
- Visual analysis, synthesis, and construction
Optional post-tests include Digit Symbol - Incidental Learning and Digit Symbol - Free Recall.
[edit] WAIS-III Subtests Grouped According to Indices
In addition to the Verbal and Performance IQ scores, the following four indices are derived.
[edit] Verbal comprehension
- Vocabulary
- Information
- Similarities
[edit] Perceptual organization
- Picture Completion
- Block Design
- Matrix Reasoning
[edit] Working memory
- Arithmetic
- Digit Span
- Letter-Number Sequencing
[edit] Processing speed
- Digit Symbol-Coding
- Symbol Search
Note: Picture Arrangement, Comprehension, and Object Assembly do not contribute to the Index Scores'
[edit] See also
- David Wechsler
- Wechsler Intelligence Scale for Children (WISC)
- Wechsler Preschool and Primary Scale of Intelligence (WPPSI)
[edit] External links
- Overview
- Official page
- More descriptions about individual tests
- PMID 12801187 - "Scoring reliability on the Wechsler Adult Intelligence Scale-Third Edition"
- PMID 10877468 - "Prorating Wechsler Adult Intelligence Scale-III summary scores"
