Relationship among scores on the Stanford Binet Form LM (SBLM) and Wechsler Intelligence Scale for Children - Third Edition (WISC-III) for gifted children

The aim of the research was to investigate the relationship between scores for gifted children on the Wechsler Intelligence Scale for Children - Third Edition (WISC-III) and the Stanford Binet Form LM (SBLM). Various criticisms have been raised regarding the validity of the WISC-III for assessing the abilities of gifted children, primarily the presence of ceiling effects and the use and interpretation of composite scores. In response to these criticisms, the SBLM has been advocated for use as a supplementary test for this population. The current study was the first to examine how the performances of gifted children differ on these two tests, with the purpose of determining under what conditions the SBLM may serve as a useful supplementary measure to the WISC-III.

The sample (N=46) was drawn from the clientele of a private psychological assessment clinic. Children (six to fifteen years) were identified to be gifted by achieving an IQ score of 125 or greater on either the verbal, performance or full scales of the WISC-III. They were subsequently assessed on the SBLM, and the results of both assessments were analysed using a multiple regression model. Results of the analyses indicated that the SBLM has a higher ceiling than the WISC-III which allows for a greater scatter of scores for gifted children. The size of the difference between SBLM IQ score and WISC-III Full Scale IQ score is significantly predicted by both the child's age and the size of their Verbal-Performance discrepancy on the WISC-III. Younger children (about 6- 10 years), and children with larger verbal-performance discrepancy scores (with verbal dominance) were significantly more likely to experience an increase in score on the SBLM relative to the WISC-III than older children, or children with lower verbal-performance discrepancy scores.

It was concluded that the WISC-III scores of gifted children should be interpreted with much caution. Particularly, the Full Scale IQ score of the WISC-III should not be taken as a global measure of the gifted child's intellectual functioning, nor should it be used as the sole criteria for the provision of gifted services. The SBLM may serve as a useful supplementary test due to its higher ceiling relative to the WISC-III. Children are most likely to experience an increase in score on the SBLM, compared with their WISC-III Full Scale IQ score, when they are younger, and also when they display stronger verbal than nonverbal skills, as indicated by their verbal-performance discrepancy score on the WISC-III.

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