Test of the Definition of Learning Disability Based on the Difference between IQ and Achievement

Abstract

A learning disability is commonly defined as a discrepancy between IQ and achievement. This has been criticized for identifying too many children as having a learning disability who have high IQs and average academic achievement. Such overidentification as actually occurred was assessed in 473 referred children (8–16 years, M= 10, SD = 2) with normal intelligence. Learning disability was defined as a significant discrepancy ( p<.05) between predicted and obtained achievement in reading, mathematics, or written expression on the Wechsler Individual Achievement Test. Predicted achievement was based on the child's WISC-III Full Scale IQ. Overidentification was considered to occur when a child scored at or above age level in reading, mathematics, and writing but still had a significant discrepancy between predicted and obtained achievement by virtue of a high IQ. Learning disability was diagnosed in 312 (66%) of the children. There was no overidentification because all children had one or more WIAT scores below the normative level for their age, i.e., < 100. Further, only 7% of the children were identified with a learning disability based on a WIAT score in the 90s. These children had a mean IQ of 123 and were rated by their teachers and parents as having learning problems.