Wechsler Intelligence Scale for Children, Assessment Example

Abstract

The Wechsler Intelligence Scale for Children, IV edition (WISC-IV) is a widely used intelligence test appropriate for children between the ages of 6 and 16. The current version, released in 2003, was renormalized to a traditional mean of 100 with a 15 point standard deviation. It is considered highly reliable and valid. It was also designed to reflect the demographics of the U.S. population as of the 2000 U.S. census. This intelligence test is considered the gold standard for intelligence testing of children, as well as being useful as a diagnostic tool for ADHD and learning disabilities.

Description of Test

The Wechsler Intelligence Scale for Children, IV edition (WISC-IV) is an intelligence test that is administered to individuals, specifically children between the ages of 6 and 16. It takes about an hour or an hour and a half to administer. The outcome of the assessment is an IQ score, thus the norm is a score of 100 and the standard deviation is approximately 15 points. The test was standardized using 2200 individuals ranging in age from 6 to 16. The developers attempted to use a sample that accurately represented the demographics of the 2000 U.S. census (Keith et al., 2006).

One issue, given the number of test scores from the WISC is whether a single low test score is indicative of clinical cognitive impairments that should be addressed clinically. Brooks (2010) studied this effect of the WISC-IV to determine the impact of such low scores. Brooks noted, for example, that if 5% of children score at or below the 5^th percentile on any given subtest, more than 20% of healthy, non-cognitively impaired children may have a score of the 5^th percentile or below on one subtest in an extended battery of tests such as the Children’s Memory Scale. Brooks (2010) thus studied the base rate of low scores on the WISC-IV to determine how clinically important a single low score on one subtest should be considered. In this study, nearly 80% of the healthy children had a score at or below the 25^th percentile. Brooks reported that about 20% of children had at least one subtest in which they scored two or more standard deviations below the mean.

Test-retest reliability of the WISC-IV in elementary and middle-school children was addressed by Ryan, Glass, and Bartels (2010). The sample size was small—only 43 students—and the test-retest was performed about 11 months apart. The stability of the test results reported varied widely from a low of 0.26 for picture concepts to 0.84 for vocabulary. More than 40% of the students showed a test-retest change of five points or more.

Development of Test

The fourth edition, WISC-IV, produced in 2003, was renormalized to reflect today’s population of children in this age group. In addition, the current edition attempts to make the test more multi-culturally friendly. The previous two-factor IQ levels of verbal IQ and performance IQ have been replaced by four factor indexes including verbal comprehension index (VCI), processing speed index (PSI), working memory index (WMI) and perceptual reasoning index (PRI) (Keith et al., 2006).

Keith et al. (2006) investigated whether the WISC-IV is truly age-invariant across the various age groups, but also found that that the various subtests do not appear to measure the stated constructs. Instead, Keith et al. found that modern learning theory such as Cattell-Horn-Carroll (CHC) theory provided a better theoretical model for the tested abilities.

Assessment of Test

The WISC-IV is considered the “gold standard” of intelligence testing in children (Keith et al., 2006). The focus on this latest version of the test was on maintaining continuity with earlier versions. It is used both to provide intelligence testing of children and as a clinical tool to diagnose issues like learning disabilities, ADHD, usually by looking for clusters of low test scores in various subtests of the WISC-IV.

References

Brooks, B. L. (2010). Seeing the forest for the trees: Prevalence of low scores on the Wechsler Intelligence Scale for Children, fourth edition (WISC-IV). Psychological Assessment, 22 (3), 650-656.

Keith, T. Z., Fine, J. G., Taub, G. E., Reynolds, M. R., Karanzler, J. H. (2006). Higher order, multisample, confirmatory factor analysis of the Wechsler Intelligence Scale for Children—Fourth Edition: What does it measure? School Psychology Review, 35 (1), 108-127.

Ryan, J. J., Glass, L. A., Bartels, J. M. (2010). Stability of the WISC-IV in a sample of elementary and middle school children. Applied Neuropsychology, 17 (1), 68-72.