The WISC-III: A reality check

Journal ofshoor Prychologv,Vol. 3 I, pp. 541-545, 1993 Pergamon Press Ltd. Printed in the USA.

The WISC-III:

0 1993 The Journal

00X?-4405/93/$6.00 + .OO of School Psychologi, Inc.

A Reality Check

Kristine R. Post and Harold R. Mitchell Richmond

(Virginia) Public Schools

Although the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) is arguably the best instrument currently available for assessing students’ intelligence, its use will present practitioners, especially school psychologists, with some unique challenges. Recent research suggests that significant reductions in special education students’ WISC-III Verbal, Performance, and Full Scale IQ scores will be found, compared with their previous WI%-R results. This finding will have a profound impact on special education placement decisions. Specifically, students who were previously found eligible for learning disability programs may now no longer evidence the significant discrepancies necessary in order to receive continued services. Conversely, students earlier identified as “slow learners” may now be eligible to receive services for those classified under the category of educably mentally handicapped. In addition, the notion that the WISC-III may underestimate the ability of certain populations of students requires further exploration. This article will address these issues as well as implications for practitioners presently administering the WISC-III.

While the introduction of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) is a welcome addition to the school psychologist’s collection of tools, there are some practical issues regarding its use that practitioners are likely to face. Kaufman’s (1993) high regard for the WISC-III is well justified. The updated norms, sound psychometric properties, and modern packaging combine to create a state-of-the-art intelligence test. Although the WISC-III

is an obvious improvement

in illuminating “school-related

over the WISC-R,

Kaufman

is accurate

some of the instrument’s shortcomings. He stated that the and culture-saturated Verbal tasks” may underestimate the

ability of minority and learning-disabled children. It is possible that children who fall into these categories will be unduly penalized, as may be reflected in a decline in their WISC-III scores. Extending this line of reasoning, the current review will discuss relevant research that has examined the differences between special education students’ WISC-R and WISC-III scores, in which the latter instrument was utilized for the triennial review. In addition, the adequacy of the WISC-III as an intelligence test and implications for professionals utilizing this instrument will be explored. The WISC-III manual (Wechsler, 1991) reported a decline in students’ Verbal (VIQ), Performance (PIQ) and Full Scale IQ (FSIQ) scores, when compared with their previous WISC-R results. Research conducted by Dumont and Faro (1993), Post (1992), and Hager (1992) also revealed similar declines. Dumont and Faro administered the WISC-III to 41 learningdisabled children who were undergoing triennial review. The results indicated Address Richmond

correspondence and reprint requests to Kristine R. City Schools, 301 N. Ninth St., Richmond, VA 23219. 541

Post,

Psychological

Services,

542

Journal of School Psychology

more substantial fluctuations than those discussed in the manual. While the manual states that differences between WISC-R and WISC-III mean scores were found to be 5, 2, and 7 points for the FSIQ VIQ and PIQ respectively, Dumont and Faro (1993) found mean score differences of 7.7 for the FSIQ 6.7 for the VIQ and 8.2 for the PIQ. Similarly, Post’s (1992) study compared current WISC-III scores with previous WISC-R scores for 68 special education students. The sample consisted of 27 learning-disabled (LD), 18 seriously emotionally disturbed (SED), and 23 mentally handicapped (MH) students undergoing triennial evaluations. Of these students, 47 were male and 21 were female. The subjects were elementary, middle, and high school students from a medium-sized, innercity public school district located in the southeastern mately 95%

of the students

United States. Approxi-

in this district

are blacks. Data revealed mean scores that were statistically WISC-III VIQ(6.4), PIQ(6.5), and FSIQ(7.0) significantly (p < ,001) lower than those obtained on the previously administered WISC-R for all three special education categories. Hager’s (1992) study also analyzed differences between WISC-R and WISCIII mean score for special education students undergoing triennial evaluations. This study utilized a sample of 90 1 l- to 14-year-old learning-disabled students from two small, rural school districts (66%) and two medium-sized, urban districts (34%) in the southeastern United States. The results of this study indicated significant declines in mean scores, on all three IQ scales, from WISC-R to WISC-III administration. Specifically, scores from the WISC-R to WISC-III was 6.0 for the VIQ and 7.0 for the FSIQ(p race (44% blacks, 56%

the decrease in 7.1 for the PIQ

< ,001). Interestingly, when data were analyzed by whites), mean score changes (blacks: VIQ = 7.1,

PIQ = 8.4, and FSIQ = 8.1; whites: VIQ = 5.5, PIQ = 5.9, and FSIQ = 6.4) were significantly greater on all three IQ scales for the black sample. The three above-mentioned studies clearly demonstrated substantial declines in special education students’mean score results from WISC-R to WISCIII.

These

findings

coincide

with existing

literature

findings

that when an

instrument measuring intelligence is revised and the norms are updated, the resulting instrument produces IQ scores that are significantly lower than those obtained on the previous instrument (Larrabee & Holroyd, 1976). It should also be noted that the authors of the present article and their colleagues, using the WISC-III, have collectively conducted hundreds of reevaluations and have repeatedly found a decline in VIQ PIQ and FSIQ scores equal to and often much greater than those reported in the studies cited above. The implications of such findings will undoubtedly influence school psychologists who make wide use of the Wechsler scales in helping to determine special education placement decisions. The use of the WISC-III and the difficulty associated with transition from prior use of the WISC-R will naturally have a great impact on special educators, administrators, parents, and especially children. Special educators and

543

Reviews and Critiques of School Psychology Materials administrators

will be confronted

whose children had previously

with the responsibility

been enrolled in learning

now no longer qualify for the program.

(For example,

of addressing

parents

disability classes, but a child who previously

scored in the low average range of intellectual ability on the WISC-R may likely fall into the borderline to “slow learner” range on the WISC-III, resulting in less of a discrepancy between ability and achievement.) In many cases, their new profile might result in their being found ineligible for continued special education services. The authors have participated in numerous eligibility decisions in which they have witnessed child after child being denied continued special education services, on the basis of the fact that they no longer exhibited a significant discrepancy between ability and achievement. Consequently, if the discrepancy model (percentage of discrepancy between ability and achievement) that is presently used in many states to determine eligibility WISC-III

for learning disability programs remains in effect, the use of the will likely decrease the number of children who are found eligible

for LD programs. This scores than the WISC-R,

trend may occur, since the WISC-III yields lower and therefore discrepancies between a child’s ability

and achievement in school will decrease for most students. Thus relying primarily on the results of an intelligence test to obtain the necessary abilityachievement discrepancies may in fact compromise the identification process. Effective alternatives to the sole use of the ability-achievement discrepancy may include closer scrutiny of perceptual processing difficulties as well as curriculum-based measurement techniques. Conversely, the use of the WISC-III may have an opposite effect on programs for the mentally handicapped. This trend will be observable through the increase in the number of students identified as mentally handicapped, compared to those previously found eligible with the WISC-R. Students who were formerly classified as slow learners (i.e., Full Scale IQ of 70-79) may be classified as mentally handicapped with the use of the WISC-III. Subsequently, practitioners will have the obligation of explaining to parents such a child suddenly qualifies for a program for mentally handicapped dents, at least on the single criterion Although this may offer a needed as slow learners, in making them services, an inevitable concern that

how stu-

of IQ. solution for children previously classified eligible for receipt of special education will arise is the likelihood of overcrowding

in classrooms for the mentally handicapped. Kirk (1978) suggests that 1520 % of schoolchildren are slow learners. However, we estimate that the population of inner-city slow learners falls beyond these percentages. Thus, the issue of overcrowding will be of special importance and present unique challenges for school psychologists employed in this type of setting. In order to address this issue effectively, it is imperative that during the transition from the use of the WISC-R to the WISC-III those involved in placement decisions consistently use other forms of data, in addition to IQ scores, as a means of reliably identifying children for special services.

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Journal of School

Psychology

Kaufman’s (1993) review of the WISC-III highlighted the new four-factor system of interpretation, in contrast to the previous three-factor structure of the WISC-R. The newest factor, Processing Speed, is derived from Coding and the additional subtest Symbol Search. Consequently, the Freedom From Distractibility factor is now composed of the Arithmetic and Digit Span subtests. The Processing visual discrimination

Speed factor appears to be useful in assessing a child’s and visual processing speed. However, we agree with

Kaufman’s assertion that additional research will be required to determine its overall usefulness for practitioners. Until further research is compiled, it is likely that school psychologists will be hesitant in routinely administering the Symbol Search subtest and interpreting the Processing Speed factor. There is consensus among many professionals that the Verbal IQ is probably a more accurate predictor of a child’s academic success in school than the Performance IQ. As previously mentioned, however, the culture-laden subtests on the WISC-III may unfairly penalize certain populations dents, often resulting in a lower Full Scale IQ. Thus, using the FSIQ

verbal of stuwhich

the LD discrepancy model often employs, may hinder certain populations of children from receiving special education services. The present authors, who work primarily with minority and culturally disadvantaged children, have found that the Performance IQ of the WISC-III is often a more reliable estimate of their students’ abilities. Overall,

the WISC-III

will undoubtedly

prove to be the instrument

of

choice for the majority of school psychologists. The instrument’s updated norms, attractive packaging, solid psychometric properties, and user friendliness all combine to create one of the best measures of intelligence currently available. Nevertheless, we remain concerned that the utilization of the WISCIII will inevitably alter the educational placement of many children. The question of whether these changes will be beneficial or detrimental to those involved will remain unanswered for some time. In addition, the assumption that the WISC-III may penalize specific populations of students is an area that warrants further investigation. Kaufman’s (1993) creative suggestion for the inclusion of an additional WISC-III scale, composed of subtests that most fairly assess the intelligence of minority, culturally disadvantaged, and learning-disabled children, is noteworthy and deserves further consideration. We believe that such a scale would increase the overall utility of the WISC-III. It is important to be mindful, however, that fluctuations in the number of students found eligible for special education services with the WISC-III does not necessarily indicate misclassification. It may merely suggest that the WISC-R has overestimated the ability of the children tested. Consequently, use of the WISC-III may enable psychologists to more accurately assess most children? cognitive abilities, thereby correctly identifying them for special education

services.

Despite

some of the limitations

of the WISC-III,

lieve practitioners in the field will ultimately benefit from endorsing fending this intelligence test during its transition years.

we beand de-

Reviews and Critiques of School Psychology

Materials

545

REFERENCES Dumont, R., & Faro, C. (1993). The WISC-III: Almost two years old; proceeding with caution-practitioners’concerns. Communique, 21(7), 12-15. Hager, V. (1992). A study of WZSC-ZZZscores in 11- to Zl-year-old learnins disabled children. Unpublished educational specialist thesis, James Madison University, Harrisonburg, VA. Kaufman, A. S. (1993). King WISC the third assumes the throne. Journal of School Psychology, 31, 345-354. Kirk, S. A. (1978). Teaching reading to slow and disabled learners. Boston: Houghton Mifllin. using Larrabee, G. J., & Holroyd, R. G. (1976). C om p arison of WISC and WISC-R a sample of highly intelligent children. Psychological Reports, 38, 1071-1074. Post, K. R. (1992). A comparison of WZSC-R and WZSC-ZZZscores on urban special education students. Unpublished educational specialist thesis, James Madison University, Harrisonburg, VA. Wechsler, D. (1991). Manual for the Wechsler Intelligence Scale for Children-Third Edition (WZSC-III). San Antonio, TX: The Psychological Corporation.