Development of Mental Abilities

DURING the past three years increased emphasis was given to theoretical issues in the organization and development of mental abilities (11, 17, 30). Some continued progress was made in the study of environmental and organismic factors but without major advances in method. In longitudinal studies, research continued to be focused on patterns of mental growth. Berkeley Growth Study findings on the development of mental ability were summarized by Bayley (12, 13). In a subsequent paper (11) on mental development in late adolescence, she reported individual differences in reaching the ceiling of growth; some individuals failed to gain beyond age 18 and others were still gaining in mental ability after age 21. Cornell and Armstrong (20), using the intelligence test data of the Harvard Growth Study, found four different patterns of mental growth. They suggested several subdivisions within each of the descriptive categories. Since these intergrade, they are not to be regarded as types of mental growth. Sontag, Baker, and Nelson (63, 64), in studies considered later in this chapter, related patterns of growth to personality characteristics and parental variables.