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Discrepancies in Scores on the WISC IV

By Inderbir Kaur Sandhu, Ph.D

Q: I would greatly appreciate any insight and advice into my daughter's test scores. These were taken a couple of years ago and she is now just turned 13. She manages to squeak by at school and get OK grades, but every day is a huge struggle of organization and frustration.

She has always seemed 'smart' but reluctant to do the work. As I understand it this profile doesn't show that she is 'gifted' but the gap between verbal skills and processing speed are the major source of the problem. However no one has been able to explain to me the huge differences in her individual scores (eg in Perceptual Reasoning from a 5 to a 15) and Verbal Comprehension (from 8 to 16).

Are there any clues here for what is really going on, and if so what should be our strategy in trying to help her reach her potential?

Verbal Comprehension -- 119
Similarities: 16
Vocabulary: 13
Comprehension: 11
(Information): 12
(Word Reasoning): 8

Perceptual Reasoning -- 92
Block Design: 6
Matrix Reasoning: 15
Picture Concepts: 5
(Picture Completion): 14

Working Memory -- 91
Digit Span: 8
Letter-Number Sequencing: 9
(Arithmetic): 10

Processing Speed -- 85
Symbol Search: 7
Coding: 8
(Cancellation): 12

Full Scale IQ -- 99

Thank you for any advice.

A: The WISC-IV consists of 10 core subtests and five supplementary subtests that can be combined in various ways to generate a full scale intelligence quotient (IQ). For instance, scores from three of the core subtests (Similarities, Vocabulary and Comprehension) are combined to calculate a Verbal Comprehension Index (VCI), which is said to be a measure of a child's ability to learn and reason with words. There are also two supplementary subtests that fit within the VCI domain. These are Information and Word Reasoning. If these subtests are administered, the scores obtained do not generally contribute to the calculation of the Verbal Comprehension Index score unless there is a clinical reason to it.

It appears that every supplementary subtest was used to assess your child but none were substituted (two substitution is allowed with caution). The five supplementary tests in fact add flexibility; however only two substitutions are allowed in different composite areas in deriving FSIQ scores (based on a clinical judgement). In your child's case, none of the substitution was used. You may want to check with the administrator of the test. For example, if your child has difficulties with her fine motor skills (a possible reason due to the lower scores in processing speed), the PSI score may be unfairly impacted because the core subtest Coding requires a degree of fine motor coordination. Therefore, Cancellation (supplementary subtest) can be used to substitute the Coding score. This is because Cancellation score does not rely as heavily on fine motor skills and may therefore provide a better measure of processing speed for this a child with fine motor difficulties.

Her verbal scores are actually similar – the supplementary subtest was used perhaps to strengthen the evidence. However, the difference is still within the normal range. The PRI requires visual perception and organization and reasoning with visually presented, nonverbal material to solve the kinds of problems that are not normally taught at school. Block Design requires visual-motor coordination and the ability to apply all skills in a quick, efficient manner. It tests visuospatial reasoning and visuo-constructional ability. The highest scores reflect both accurate and very quick responses. Low scores suggests poor perceptual abilities, difficulties with visual integration, and likely problems with maintaining a sustained effort. For picture concept as well, her score was lowest compared to the other subtests under Perceptual Reasoning indicating perhaps poor nonverbal concept formation, rigid thought processes and poor abstract reasoning.

The Matrix Reasoning subtest requires nonverbal reasoning and concept formation, which your daughter did very well. Matrix Reasoning is about problem solving/reasoning and Block Design and Picture Completion are about perception/sensory processing. So once the data is in the brain it gets processed well, but getting it in may be difficult.

As for the scatter, there is not diagnostic indication but it could like a pattern in children within the Autism Spectrum. Especially for children with Asperger's Syndrome, scatter in sub-test scores is characteristic, and a verbal vs. performance IQ gap is not uncommon. Having said that, not all autistics have large subscores gaps. It is true that many do and it could point to a sign that autism can be considered; but it is not required for nor diagnostic of autism. They can be useful in determining concerns such as a possibility of NVLD/AS though, especially when you look specifically at the pattern of subtest scores that children with disorders often exhibit.

It is best to seek professional advice and perhaps take further diagnostic tests to eliminate some of the conditions and if any concern is diagnosed, it is not late at all to start intervention. Do seek further help. All the best.


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