Differences in the intellectual profile of children with intellectual vs. learning disability.
A big GAI-CPI split on the WISC-IV tips the scale toward learning disability, even when full-scale IQ is low.
01Research in Context
What this study did
Cornoldi et al. (2014) looked at WISC-IV scores from kids with learning disabilities and kids with intellectual disability.
They checked two numbers: the General Ability Index (GAI) and the Cognitive Proficiency Index (CPI).
The goal was to see if the gap between these numbers helps tell the groups apart.
What they found
The SLD group had a high GAI and a low CPI. The ID group had both scores flat and low.
Even when the child’s full-scale IQ was under 85, the pattern still held.
A big GAI-CPI split points toward learning disability, not intellectual disability.
How this fits with other research
Laugeson et al. (2014) meta-analysis shows kids with ID have large deficits in behavioral and interference inhibition, but not in cognitive or motivational inhibition. Cesare’s work adds that the WISC-IV profile, not just inhibition, helps separate ID from SLD.
Wright et al. (2024) found globally low adaptive skills in SYNGAP1-ID. Cesare’s data remind us that low IQ alone does not rule out SLD; check the index gap before assuming ID.
van Tilborg et al. (2018) report that phonological awareness predicts early literacy less in ID than in typical kids. Cesare’s study supports the wider point: use specific cognitive patterns, not just total IQ, to guide decisions.
Why it matters
When you see a low full-scale IQ, pause before labeling ID. If the GAI is markedly higher than the CPI, think learning disability first. This small check can stop misdiagnosis and keeps you targeting the right goals in your treatment plan.
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02At a glance
03Original abstract
The WISC-IV was used to compare the intellectual profile of two groups of children, one with specific learning disorders (SLDs), the other with intellectual disabilities (ID), with a view to identifying which of the four main factor indexes and two additional indexes can distinguish between the groups. We collected information on WISC-IV scores for 267 children (Mage=10.61 [SD=2.51], range 6-16 years, females=99) with a diagnosis of either SLD or ID. Children with SLD performed better than those with ID in all measures. Only the SLD children, not the ID children, revealed significant differences in the four main factor indexes, and their scores for the additional General Ability Index (GAI) were higher than for the Cognitive Proficiency Index (CPI). Children with a diagnosis of SLD whose Full-Scale Intelligence Quotient (FSIQ) was <85 showed a similar pattern. Our findings confirm the hypothesis that children with SLD generally obtain high GAI scores, but have specific deficiencies relating to working memory and processing speed, whereas children with ID have a general intellectual impairment. These findings have important diagnostic and clinical implications and should be considered when making diagnostic decisions in borderline cognitive cases.
Research in developmental disabilities, 2014 · doi:10.1016/j.ridd.2014.05.013