Cumulative deficit: A testable hypothesis?

Abstract

Cumulative deficit is an hypothesis concerning the cause of lower mental test scores of groups considered environmentally deprived. It presupposes a progressive decrement in test scores, relative to population norms, as a function of age. Clarification of the theoretical issues and the methodological problems involved in establishing the progressive decrement phenomenon are discussed in relation to the relevant research on disadvantaged groups, especially American Negroes. In this group in particular there is no methodologically adequate evidence in the literature for a progressive decrement in IQ or other mental measurements. The present study,'using differences between younger and older siblings, which satisfies more rigorous methodological requirements for the detection of progressive decrement than have existed in previous studies, found a significant age decrement in verbal but not in nonverbal IQ among a large sample of Negro elementary school children, although the mean white-Negro difference is similar for nonverbal IQ and verbal IQ. The term cumulative deficit refers to one of the most fundamental concepts in the now vast literature of environmental deprivation and cultural disadvantage. It is also the keystone of the rationale for compensatory