Research-Based Guidelines for Use of the
WISC-IV in Gifted Assessment

By Barbara Gilman and R. Frank Falk

A presentation for the Symposium: A Comparison of Assessment Techniques
in the Identification of Gifted Learners

16 th Biennial Conference of the World Council for Gifted and Talented Children

August 7, 2005
New Orleans, Louisiana

The Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV), released in 2003, boasts stronger adherence to theory, extended ceiling (more difficult items at the high ends of subtests), enhanced assessment of visual-spatial abilities with less timing, and increased emphasis on processing skills (working memory and processing speed with paper-and-pencil tests). With these modifications, is the full test a successful instrument for gifted identification? Are certain portions better indicators of giftedness than others? What guidelines are warranted for use of the WISC-IV with gifted children?

The gifted group in the WISC-IV normative sample earned discrepant Composite/Index scores when compared with the control group. While scores of the Control Group varied by less than four points across the Index areas, scores for the Gifted Group varied by over 14 points. Scores were as follows:

WISC-IV Normative Sample, N=63

(WISC-IV Technical Manual, p. 77)

Large scoring variances raise concerns about subtest selection and the weighting of the four Indices in the Full Scale IQ. When the 15 subtests are ranked from highest to lowest according to mean scores, four of five subtests in the top 10 are supplemental (not used in calculation of the Index or Full Scale IQ scores), while the four core (used in calculation of global scores) subtests from the Working Memory and Processing Speed Indices are among the five lowest scoring in the gifted sample (Flanagan & Kaufman, p. 223). Working Memory and Processing Speed subtests now account for 40% of core subtests on the WISC-IV, up from 20% on the WISC-III.

The evaluation of 103 children at the Gifted Development Center in Denver sheds further light on the effectiveness of changes in the WISC-IV and offers guidance for both testers assessing the gifted population and gifted program administrators using the WISC-IV to meet admission criteria. Scores are as follows:

Gifted Development Center (GDC) Study, N=103

*Arithmetic was substituted for Letter-Number Sequencing in 102 of 103 cases (for all children unless mathephobic).

**The GAI is calculated from mean VCI and PRI scores for illustration.

GDC scores reflect even greater disparity, with Verbal Comprehension, Perceptual Reasoning, and Working Memory Index scores rising and Processing Speed falling relative to the Gifted Group in the normative sample. Working Memory scores in the GDC sample reflect the substitution of Arithmetic for Letter-Number Sequencing. This was done to include a more meaningful memory task in the Working Memory Composite, to help identify mathematically talented children, and because Arithmetic has one of the highest g-loadings and is highly correlated with intelligence.

Overall variance of Index scores exceeded 27 points—almost two standard deviations. Flanagan & Kaufman advise against the use of the Full Scale IQ score as a global estimate of ability when the disparity between Index scores is equal to or greater than 1.5 standard deviations or 23 points (p. 128). How frequently does this happen? In 79% of GDC cases, the Full Scale IQ score was uninterpretable due to extreme discrepancies between Index scores. In such cases the General Ability Index (GAI) is recommended, provided that the Verbal Comprehension and Perceptual Reasoning scores differ by less than 23 points. How frequently did they exceed 22 points? Sixteen children (16%) were not qualified for either the GAI or the Full Scale IQ.

When significant disparities exist, what approach should be taken to summarize abilities or otherwise identify gifted children for programs? Results of the Gifted Development Center study indicate that the four Composite or Index areas of the WISC-IV yield scores too divergent for the Full Scale IQ score to be relied upon as a valid global estimate of ability. Requiring gifted-level WISC-IV Full Scale IQ scores for admission to gifted programs is, therefore, not recommended. Alternate subtest choice (e.g., substituting Arithmetic for Letter-Number Sequencing or Digit Span) and use of the General Ability Index (GAI), instead of the Full Scale IQ, can improve identification of gifted children when applied appropriately. Administering only the WISC-IV Verbal Comprehension and Perceptual Reasoning subtests for gifted identification is also a reasonable alternative. The Verbal Comprehension and Perceptual Reasoning Indices are each powerful indicators of giftedness, sufficient to warrant placement of a child in a gifted program.

Guidelines for Use of the WISC-IV in Gifted Assessment

• Recommend children for gifted programs based on a score of 130 in either Verbal Comprehension or Perceptual Reasoning. These scores are excellent indicators of advanced reasoning abilities.
• Alternatively, require a General Ability Index (GAI) score in the gifted range (130) or somewhat lower (e.g., 125), a more cautious choice.
• If WISC-IV Full Scale IQ’s are mandated for program admission, require scores no higher than 123.

References

Falk, R. F., Silverman, L. K., & Moran, D. (2004, November). Using two WISC-IV indices to identify the gifted. Paper presented at the 51 st Annual Convention of the National Association for Gifted Children, Salt Lake City, UT.

Flanagan, D. P., & Kaufman, A. S. (2004). Essentials of WISC-IV assessment. Hoboken, NJ: John Wiley & Sons.

Silverman, L. K., Gilman, B. J., & Falk, R. F. (2004, November). Who are the gifted using the new WISC-IV? Paper presented at the 51 st Annual Convention of the National Association for Gifted Children, Salt Lake City, UT.

Wechsler, D. (2003). The WISC-IV technical and interpretive manual. San Antonio, TX: Psychological Corporation.