Critique of Wechsler Adult Intelligence Scale-Fourth Edition

Critique of Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV)

Critique of Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV)

WAIS-IV Purpose

The Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) is the latest iteration of the adult (ages 16 to 90) intelligence test first developed in 1939. Though WAIS-IV has a total of 15 subtests, 10 of them are core subtests, which are administered in a prescribed order to calculate six scores including FSIQ (Full Scale IQ) while endeavoring to measure general intelligence by evaluating four cognitive skill categories: “Verbal Comprehension (4 subtests), Perceptual Reasoning (5 subtests), Working Memory (3 subtests), and Processing Speed (3 subtests).” In the 77 years since the first edition of WAIS (then called the Wechsler-Bellevue Intelligence Scale), the instrument has retained “the same general theoretical and administrative structure” and remains rooted in Spearman’s g hierarchical model of intelligence as well as the two-factor theory of Cattell (Canivez, 2010; Schraw, 2010).

Mental Measurements Yearbook (MMY) Review of WAIS-IV

There are two reviews of WAIS-IV in the Eighteenth Mental Measurements Yearbook (MMY), written each by Canivez and Schraw. Canivez is the higher quality of the two articles, as its 23 references cover the full range of topics from the WAIS’s historical and current theoretical underpinnings, a thorough review of WAIS factors and subtests with pertinent associated measures, and (modern) research addressing measures of intelligence. By contrast, Schraw, which cited seven references and focuses more narrowly on the WAIS tradition and theory, while reviewing a smaller selection of modern work on the nature of intelligence (Canivez, 2010; Schraw, 2010).

Administering the WAIS-IV

The WAIS-IV is developed for individuals (not groups) 16 years to 90 years, 11 months (Benson, Hulac, & Kranzler, 2010; Spies, Carlson, & Geisinger). It takes 59-100 minutes to administer (Spies et al.) and requires additional examiner time to score and interpret results such that its use “may be most appropriate when high-stakes decisions are made” (Schraw, 2010). The WAIS-IV standardization sample included 2,200 Americans who were closely reflective of the demographic make-up of the United States when compared to the October 2005 US Census data (Canivez, 2010). There are no alternate WAIS-IV test forms; however, clinicians may substitute one or more of the core subtests with one of the optional subtests (as prescribed by the manual). Though FSIQ gets the greatest notice, it is but one of six total scores (the others are VCI [verbal comprehension index], PRI [perceptual reasoning index], PSI [processing speed index], GAI [general ability index]). All scores are determined by adding appropriate subtest scores (some of which must be scaled as prescribed in the manual) and normalized (if required) (Benson et al., 2010; Spies, et al.).

WAIS-IV Reliability

Canivez reports high reliability from reviews of the three reliability measures provided in the WAIS-IV technical and interpretive manual: “internal consistency, test-retest stability, and interscorer agreement.” “Internal consistency estimates across all 13 age groups ranged from .97-.98 for the FSIQ; from .87-.98 for the factor index scores (VCI, PRI, WMI, PSI); and from .71-.96 for the subtests.” Relatively stable short-term (average of 22 days) test-retest stability was measured for 298 participants; however, longitudinal research will be needed to assess long-term scoring stability. An evaluation using three WAIS-IV publisher-trained raters independently scored the four Verbal Comprehension subtests (where examiner judgment is required) and high “intraclass correlation coefficients” of .91-.97 were observed. The above measures provided above suggest high reliability/predictability of test results (Canivez, 2010).

WAIS-IV Validity

Relatively strong correlations between WAIS-IV and WIAT-II (Wechsler Individual Achievement Test-Second Edition) were observed in a study of ninety-three 16-19 year olds—specifically .65-.88 when correlating WAIS-IV FSIQ scores to WIAT-II composite scores and .42-.80 for WIAT-II subtests; similar results were observed in a smaller sample that reviewed the more recent WIAT-III (Third Edition). Additionally, several small sample group studies designed to evaluate the extent to which WAIS-IV reflected a number of conditions (including intellectual disabilities, reading or mathematics disorders, attention deficit-hyperactivity disorder, traumatic brain injury, autism, Asperger's disorder, major depression, mild cognitive impairment, and Alzheimer's dementia) and observed predicted shifts appropriate to the respective conditions (Canivez, 2010).

WAIS-IV Limitations

In the MMY, Benson, Hulac, & Kranzler offer a critique that WAIS-IV developers continue to favor adherence to the historical WAIS structure, only slowly introducing elements of contemporary advances in theory. This need for theoretical grounding is underscored by the irony that CHC (Cattell-Horn-Carroll) theory offers better explanations of WAIS-IV performance than does the instrument’s own scoring structure insofar as their review of scores for ages 16 years to 69 years, 11 months were concerned (ages 70 and above were excluded as three WAIS-IV subtests are non-applicable to individuals in this range), though CHC theory does not fully explain all aspects of WAIS-IV (Benson, et al., 2010).