Dyslexia and Giftedness – By the Numbers
A new study by Italian researchers suggests that the rate of intellectual giftedness among students with dyslexia and related learning disabilities may be almost double the rate among typically developing children. However, these talents may often be hidden by the way that educators and other professionals evaluate findings from commonly used measures of intelligence.
The researchers examined a database of more than 1400 children who had been found to have learning disabilities based on measures of achievement of below the 5th percentile in at least one academic area. They then looked for students who had also had IQ scores of above 130 on the WISC-IV, and compared their scores with a database of 2200 typically developing students.
The WISC-IV consists of a number of subtests and typically is interpreted to yield a “full scale” IQ (FSIQ) score, based on a combination of scores in all areas. However, some of the subtests are also strongly associated with weaknesses that are also symptomatic of dyslexia and similar learning disabilities, particularly measures of Working Memory and Processing Speed. That means that when these criteria are included within the calculation of full scale IQ, children with learning disabilities will be scored lower overall because of the disability.
However, as an alternative, evaluators can optionally use a General Ability Index (GAI) which is a composite WISC score that does not include the Working Memory and Processing Speed measures, but is based only on the core Verbal Comprehension and Verbal Reasoning subtests. This approach is recommended by many educators, especially for evaluating children for giftedness, as it may more accurately reflect cognitive ability, especially among students with learning disabilities.
The Italian researchers found that when using the GAI, the rate of giftedness among the LD students was twice as high as among typically developing students. (3.75% compared to 1.85%). They also found that while the GAI scores of typically-developing children were only marginally higher than the FSIQ, there was a mean gap of almost 12 points between FSIQ and GAI among students with learning differences. Among the study group, reliance on FSIQ would fail to identify more than 80% of the students who would qualify as gifted based on GAI scores of 130 or above.
This study both confirms anecdotal reports of high rates of intellectual giftedness among students with learning differences, and provides guidance to educators as to appropriate standards for assessing giftedness among such students.
It should also be noted that the Italian standard for identifying students with learning disabilities, requiring achievement scores at or below the 5th percentile, is particularly strict. This standard is based on identifying only students who score two standard deviations below average as having a specific learning disability, which would tend to under-identify students with above-average IQs. The alternative IQ discrepancy model would identify learning disabilities based on specific achievement scores two standard deviations below the level that would be expected based on the student’s IQ. It is likely that a far greater percentage of students with IQ’s above 130 would be found to also have specific learning difficulties based on that model, which would in turn suggest an even higher concurrence of giftedness with learning differences.
Einstein and dyslexia: Is giftedness more frequent in children with a specific learning disorder than in typically developing children? Enrico Toffalini, Lina Pezzuti, Cesare Cornold. Intelligence . In Press, 2017 | DOI: https://doi.org/10.1016/j.intell.2017.04.006
https://blog.dyslexia.com/dyslexia-and-giftedness-by-the-numbers/Davis TheoryDyslexia ResearchDyslexic Talents