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Processing Speed Index of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV)
Processing Speed Index of the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV)
| Availability |
Please visit this website for more information about the instrument:
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| Classification |
NeuroRehab Supplemental - Highly Recommended
Recommendations for Use: Indicated for studies requiring a measure of processing speed.
Basic: Acute, Moderate and Mild Traumatic Brain Injury (TBI)
Supplemental: Epidemiology TBI
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| Short Description of Instrument |
Publication Date: 2008
Ages/Grades: Individuals 16-90 years
Scores: VIQ, PIQ, and FSIQ scores
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| Comments/Special Instructions |
Description
This index is based on 2 subtests of the Wechsler Adult Intelligence Scale 3rd and 4th Editions. For Coding, examinee must accurately fill in symbols, according to matched number-symbol pairs in a key in 120 seconds. For Symbol Search, examinee determines whether either of two target symbols match any of the symbols in a search group; examinee must respond to as many items as able in 120 seconds.
Permissible Values
The 2 subtests yield scaled scores adjusted for age with a mean of 10 and standard deviation of 3. The WAIS-III/IV PS Index is based on the 2 subtests with a mean of 100 and standard deviation of 15 adjusted for age.
Procedures
Requires trained examiner to administer and neuropsychologist or psychologist to interpret. Administration time is 10 minutes.
Comments
This is a performance-based measure which requires the subject to understand what is required and participate in the testing. It requires a functional level in the severe disability or above on the GOS/GOSE.
Rationale
Good psychometric properties. Sensitive to TBI and its severity. Legacy measure for NIH Toolbox Processing Speed Subdomain.
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| Comments |
DESCRIPTION
This index is based on 2 subtests of the Wechsler Adult Intelligence Scale. For Digit Symbol, examinee must accurately fill in symbols, according to matched number-symbol pairs in a key in 120 seconds. For Symbol Search, examinee determines whether either of two target symbols match any of the symbols in a search group; examinee must respond to as many items as able in 120 seconds.
PERMISSIBLE VALUES
The 2 subtests yield scaled scores adjusted for age with a mean of 10 and standard deviation of 3. The WAIS PS Index is based on the 2 subtests with a mean of 100 and standard deviation of 15 adjusted for age.
PROCEDURES
Requires trained examiner to administer and neuropsychologist or psychologist to interpret. Administration time is 10 minutes.
COMMENTS
This is a performance based measure which requires the subject to understand what is required and participate in the testing. It requires a functional level in the severe disability or above on the GOS/GOSE.
RATIONALE
Good psychometric properties. Sensitive to TBI and its severity. Legacy measure for NIH Toolbox Processing Speed Subdomain.
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| Scoring and Psychometric Properties |
Scoring
For Symbol Search - Scoring includes the total number of correct responses minus the items completed incorrectly to get a total score. A skipped item is not scored as incorrect.
For Coding - Score one point for each correct response.
Psychometric Properties
Psychometric properties for both scales are presented in detail in the WAIS-IV technical manual.
Coding: Split-half reliability = 0.86; Test-retest reliability = 0.86
Symbol Search: Split-half reliability = 0.81; Test-retest reliability = 0.81.
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| Rationale/Justification |
Strengths: Part of well-validated WAIS-IV, brief to administer, broad utility, comprehensive norms with demographic corrections and applicability across many different populations that are common in rehabilitation. Good measures of pure processing speed.
Weaknesses: Motor dependent and no oral versions available. These subtests are part of a battery that requires a purchase of the entire program to use.
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| References |
Lichtenberger EO & Kaufman AS. (2012). Essentials of WAIS-IV assessment (Vol. 96). John Wiley & Sons.
Wechsler Adult Intelligence Scale III. Letter-Number Sequencing Subtest. Pearson Education Inc, San Antonio, TX.
Wechsler Adult Intelligence Scale IV. (2008). Letter-Number Sequencing Subtest. Pearson, San Antonio, TX.
Document last updated January 2022
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