General maturational lag as an essential correlate of early-onset psychosis.

Evidence for the increasing recognition of maturational lag in addition to intellectual impairment, associated with the syndrome of early-onset psychosis, is presented to indicate that developmental variables play a central role in the behavioral profile of autistic children. The failure of research to give methodological consideration to control of these variables is discussed, and implications for the interpretation of results from experimental studies are outlined. It is suggested that the distinction between controlling not only for mental age but also for chronological age to facilitate the delineation of specific deficits in this syndrome.