It is important to know whether the major instruments in the field, such as the Wechsler scales and Stanford-Binet Test of Intelligence, adequately assess intelligence in a given case. If they do not, clinically acceptable and programmatically workable alternative instruments should be explored. This may entail identifying other instruments (including nonverbal intelligence assessment instruments as well as instruments available in languages other than English) that have sufficient reliability and validity to adequately diagnose mental retardation. Of course, any additional instruments identified should have the potential for wide use in clinical practice settings.
A number of research areas have produced reliable findings that are relevant and ready for implementation in practice. Advances in the assessment of developmental functioning have expanded the examination of intelligence from a dependence on verbal and performance intelligence scores to a broader view that incorporates measures of process as well as product. Multiple components that comprise intellectual functioning can now be more easily separated, for example, attentional processes, computational processes, problem-solving skills, and performance processes.
In the area of developmental assessment, standardized preschool measures of competence (Bayley, 1993) are required to assess multiple domains of functioning. These include fine motor, gross motor, cognitive, communication, and social skills. Impairment judgments based only on verbal and performance IQs may not reflect current intelligence testing practices for preschool children. The committee was charged with determining if other instruments better assess young children’s intellectual functioning.
For individuals with an intelligence score greater than 59, SSA requires documentation of deficits in adaptive behavior and functioning in order for a classification of mental retardation to be made, as long as no other serious medical condition is present. This may include the results of standardized tests (e.g., Scales of Independent-