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New Method of Scoring IQ Tests Benefits Children With Intellectual Disabilities

Typical intelligent quotient (IQ) tests are scored according to the mean performance of children without disabilities. The result is that the raw scores of many children with intellectual disabilities are converted into the lowest normalized score, typically a zero. An IQ report with a score of zero tells parents a little to nothing about the long-term learning potential of their children.

David Hessl, an associate professor of clinical psychiatry and a researcher at the UC Davis M.I.N.D. Institute, and a team of collaborators have devised a new system of scoring IQ tests taken by children with fragile X syndrome, a genetic disorder that causes intellectual disabilities, including autism. The details of the new method are described in a study published by the Journal of Neurodevelopmental Disorders.

According to Hessl, there is a lot of meaningful variability in the performance of these children on IQ tests. "We believe that this variability is important information about the relative strengths and weaknesses that these children have," Hessl explained. Frustrated by the lack of sensitivity of IQ tests, Hessl set out to devise a scoring method that would reveal the strengths and weaknesses of each child.

"If this new method becomes widely available, we will be able to tell parents something more useful and more accurately diagnose and treat young children who are learning disabled," said Hessl.

On the new scale, children scored as low as minus 10 on 14 subtests. These included verbal, arithmetic, picture completion and object assembly. Like normalized scores of children without disabilities, the frequency of the new normalized scores for children with fragile X syndrome followed an expected, bell-shaped distribution.

"These new scores tell us more precisely how a child with fragile x syndrome deviates from the normal population in every sub-test area," Hessl said.

"I think we've made a good case for the makers of the Wexler IQ test and others to release raw data to researchers so that this method can be applied to other populations with intellectual disabilities," Hessl said.

For more details about this study, click here.