ABSTRACT
Historically, mental retardation has been defined in terms of cognitive and behavioral deficiencies. Currently, according to the American Association on Mental Retardation (1992):
Mental retardation refers to substantial limitations in present functioning. It is characterized by significantly subaverage intellectual functioning, existing concurrently with related limitations in two or more of the following applicable adaptive skill areas: communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academics, leisure, and work. Mental retardation manifests before 18.
From an etiological perspective, theories of mental retardation have stressed the critical influences of cognitive defects in limiting adaptive skills. Considerable attention has been placed on documenting and delineating the cognitive deficiencies of the mentally retarded, the neurological bases for these cognitive deficiencies, and how cognitive functioning influences behavioral functioning.