Differential WAIS/WAIS-R IQ discrepancies among institutionalized mentally retarded persons

Compared to the Wechsler Adult Intelligence Scale, the Wechsler Adult Intelligence Scale-Revised (WAIS-R) is generally reported to result in IQs that are somewhat lower for nonretarded subjects and unchanged for retarded subjects. In the present study these findings were replicated with subjects in a residential treatment center, except that the moderately retarded subgroup demonstrated significantly higher WAIS-R IQs (mean increase of 6 points in Full Scale IQ), with reclassification as mildly mentally retarded possible for 64% of these persons. Such differential, level-specific effects require careful interpretation of WAIS-R IQs of retarded persons in the context of actual adaptive skills.