THE WECHSLER INTELLIGENCE SCALE FOR CHILDREN- FOURTH EDITION (WISC-IV)
BACKGROUND : The Wechsler Intelligence Scale for Children (WISC) was first published in 1949. It represented a downward extension of the W-B and actually incorporated many items contemplated for use in the (never-published) W-B II. “A well-standardized, stable instrument correlating well with other tests of intelligence” (Burstein, 1972, p. 844), the WISC was not without its flaws, however. The standardization sample contained only White children, and some of the test items were viewed as perpetuating gender and cultural stereotypes. Further, parts of the test manual were so unclear that it led to ambiguities in the administration and scoring of the test.
A revision of the WISC, called the Wechsler Intelligence Scale for Children-Revised (WISC-R), was published in 1974. The WISC-R included non-Whites in the standardization sample, and test material pictures were more balanced culturally. The test’s language was modernized and “child-ized”; for example, the word cigars in an arithmetic item was replaced with candy bars. There were also innovations in the administration and scoring of the test.
The revision of the WISC-R yielded the Wechsler Intelligence Scale for Children III, published in 1991. This revision was undertaken to update and improve test items as well as the norms.
THE TEST TODAY : The WISC-IV is the latest version of this scale to measure global intelligence and, in an attempt to mirror advances in the understanding of intellectual properties, the WISC-IV also provides composite index (Wechsler, 2003). The original form of the WISC was based on Form 11 of the Wechsler–Bellevue scale, which provided a point scale measure of intelligence for children between the ages of 6 years and 16 years, 11 months. The WISC-IV contains 15 subtests, 10 of which were retained from the earlier WISC-III and 5 entirely new ones. Three subtests used in earlier versions- picture arrangement, object assembly, and mazes- were entirely deleted.
Related Topics :
List of subtests
As with the modern Binet, the modern WISC-IV has updated its theoretical underpinnings. In addition to the important concept of fluid reasoning, there is an emphasis on the modern cognitive psychology concepts of working
memory and processing speed. To add to its clinical utility, the test manual provides numerous studies of special groups, and the WISC-IV is linked to an achievement test (the Wechsler Individual Achievement Test, or WIAT-II),which is also published by the Psychological Corporation (2001).
memory and processing speed. To add to its clinical utility, the test manual provides numerous studies of special groups, and the WISC-IV is linked to an achievement test (the Wechsler Individual Achievement Test, or WIAT-II),which is also published by the Psychological Corporation (2001).
INTERPRETATION :
Interpretation of the WISC-IV also parallels that of the WAIS-III. The basic approach involves evaluating each of the four major indexes to examine for deficits in any given area and evaluate the validity of the FSIQ. To the extent that large discrepancies exist in the indexes, the validity of the FSIQ falls into question. The next step would be to consider the underlying functions measured by each of the subtests and again determine whether large discrepancies exist between one subtest and another, or between one subtest and the overall mean of the subtests. As a simple example, if all subtests are roughly average except for an extremely low score on working memory, the clinician would hypothesize a specific deficit in working memory.
Reliability of the WISC-IV
When the WISC-IV was revised, developers intended to maintain the strong psychometric properties of its predecessors , which they largely did. The procedure for calculating reliability coefficients for the WISC-IV was analogous to that used for the WISC-III and WAIS-IV. Split-half reliabilities for the WISC-IV composites range from .88 for processing speed to .97 for the FSIQ (Wechsler, 2003, p. 35). Naturally, reliabilities for individual subtests run lower, as in all forms of tests.
When the WISC-IV was revised, developers intended to maintain the strong psychometric properties of its predecessors , which they largely did. The procedure for calculating reliability coefficients for the WISC-IV was analogous to that used for the WISC-III and WAIS-IV. Split-half reliabilities for the WISC-IV composites range from .88 for processing speed to .97 for the FSIQ (Wechsler, 2003, p. 35). Naturally, reliabilities for individual subtests run lower, as in all forms of tests.
Validity of the WISC- IV
In a study published in 2012, using a population of 1100 children aged 6 through 16, using the WISC-IV core subtests, researchers investigated measurement invariance of the WISC-IV second-order factorial structure between normative and clinical samples. One fundamental aspect of validity is that of measurement invariance, i.e., that the assessment measures the same thing in different populations. In this study, results supported measurement invariance across normative and clinical samples (Chen & Zhu, 2012). Only coding and comprehension subtest intercepts varied slightly between groups. The hypothesized WISC-IV factor model described the data well. Factor patterns, first- and second-order factor
loadings, intercepts, residual variances of measured subtests, and disturbances of first-order factors of the WISC-IV were generally invariant. Results suggested that WISC-IV index scores and subtests have the same meaning for children in both normative and clinical groups (Chen & Zhu, 2012).
Another study asked whether the WISC-IV measured the same thing in a normative sample and in a sample of individuals with intellectual disabilities (Bowden, Saklofske, & Weiss, 2011). The model satisfied the assumption of invariance across samples with subtest scores reflecting similar construct measurement in both samples. The results demonstrate the generality of construct validity in measurement of cognitive abilities. Thus, there is much evidence of the validity of the
WISC-IV.
loadings, intercepts, residual variances of measured subtests, and disturbances of first-order factors of the WISC-IV were generally invariant. Results suggested that WISC-IV index scores and subtests have the same meaning for children in both normative and clinical groups (Chen & Zhu, 2012).
Another study asked whether the WISC-IV measured the same thing in a normative sample and in a sample of individuals with intellectual disabilities (Bowden, Saklofske, & Weiss, 2011). The model satisfied the assumption of invariance across samples with subtest scores reflecting similar construct measurement in both samples. The results demonstrate the generality of construct validity in measurement of cognitive abilities. Thus, there is much evidence of the validity of the
WISC-IV.
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