Profound developmental retardation: descriptive and theoretical utility of the Bayley Mental Scale.

Although infant developmental tests have been available for decades, their employment in the analysis of profound developmental retardation has been limited to the prediction of later retardation and the global evaluation of intervention effects. This report summarizes a descriptive study of a sample of profoundly retarded, organically impaired children and adults (IQ less than 15), all of whom were administered the Mental Scale of the Bayley Scales of Infant Development (BSID). One purpose was to promote a more empirically based as well as developmentally oriented treatment of profound retardation, one that bears a closer relationship to the study of normal intellectual development. Another purpose was to examine the reliability of the Mental Scale as tool for assessing behavioral repertoires and for evaluating the effects of intervention with the profoundly retarded. With several qualifications related to test-retest reliability, the Bayley Mental Scale appears capable of serving both descriptive and theoretical functions, and thus of assisting in the organization of new approaches to intervention with profoundly retarded and organically impaired individuals.