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Discrepancy between Subset Scores on the WISC-IV

By Inderbir Kaur Sandhu, Ph.D

Q: My 9 year old son just took the WISC IV and the Stanford Binet Intelligence Scale section for Quantitative Reasoning and scored the following:

Weschler Intelligence Scale for Children - fourth edition

Full Scale score: 104 Percentile = 61

  • Verbal Comprehension Composite 100 Percentile = 50

  • Perceptual Reasoning Composite 90 Percentile = 25

  • Working Memory Composite 113 Percentile = 81

  • Processing Speed Composite 112 Percentile = 79

Stanford Binet Intelligence Scale

Quantitative Reasoning 103 Percentile = 60

His school is telling me that he is not qualified for excel classes. I do not understand their reasoning. I also feel there is a need for more testing due to the big difference between PRI, VCI and WMI, PSI. Through researching about this type of IQ test, I have found that when there is a big difference between the four categories (verbal, perceptual, working processing) that additional testing is needed. Am I correct?

Please help me help my son, who has lost interest in school and is bored. He has been since K. I have been battling school for a while now. This year they finally agreed to the above tests. I am a little concerned that the psychologist who administered the test is his school's psychologist.

PS: I have a meeting scheduled with the school's director of student services, principal, reg. teacher, excel teacher, psychologist and excel program director.

A: It is unclear on the kind of results you were expecting. Is your son showing signs of superior intelligence in an area but is not reflected in the scores? Based on the standard norms, his full scale IQ score is in the average range (90-109). His WMI and PSI are in the above average range; however brought down by his VCI and PRI scores.

It has been noticed that some of the Full Scale IQ scores on the WISC-IV are excessively lowered by either VCI and PRI or WMI and PSI scores. Due to the fact that intelligence is primarily abstract reasoning ability, emphasis on short-term auditory memory and processing speed on paper-and-pencil tests is less helpful.

In general the VCI is considered one of best predictors of overall intelligence. Sometimes a low score occurs because the child has acquired the information but does not have the expressive language to demonstrate it. His WMI is high though which is the ability to temporarily retain information in memory, perform some operation or manipulation with it, and produce a result It also involves attention, concentration, mental control, reasoning. This is an essential component of other higher order cognitive processes and is closely related to achievement and learning and frequently affected in learning disability. He also showed high PSI which is the ability to quickly and correctly scan, sequence, or discriminate simple visual information, short-term visual memory; attention and visual-motor coordination. Therefore he is showing clear strength in WMI and PSI and weakness in VCI and PRI.

You are right to suspect that the huge gap between the scores should warrant for further testing. However, the GAI (General Ability Index) should only be used in this case instead of the Full Scale IQ (FSIQ), if the four composite scores vary by 23 or more points - which is not the case here.

You indicated that your son is bored at school since preschool years but did not indicate the reason. This has been going on for a while now; perhaps there is another underlying concern that has not been attended to. About the school psychologist, I believe even if there is some sort on favouring or otherwise, the scores should not be too far off. However, if you suspect something, it is best to speak to someone in authority from the school. Do voice out your concern clearly and ask or suggest what may be best for your son. If you are still unhappy, see an educational psychologist who may be able to further test your son and suggest suitable learning interventions to help him with his weak areas and enhance his abilities. Good luck!


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