The mental age deficit: explanation and treatment.

Mildly and moderately retarded persons perform in many psychological tasks, by definition, at lower levels than do nonretarded persons of equal chronological age (CA), but they also perform often at lower levels than do younger nonretarded persons of equal mental age (MA). "MA deficit" appears to derive in large part from experience, especially in four domains: (a) behavioral incompetence; (b) deficient cognitive structures, including the special case of communicative incompetence; (c) relative task-extrinsic motivational orientation; (d) negative social ecology, i.e., unproductive person-setting matches. The very experience of being retarded makes one more so. Treatment designed at least to overcome the MA deficit should be focused on these domains.