Effect of Childrearing Practices on Development of Differential Cognitive Abilities1

Individual differences in cognitive development have come to be considered the result of interactions between a child's life experiences and the set of genes with which he has been endowed. Relations have been found between cognitive abilities and perceptual and cognitive style on one side and personality traits on the other side, and some investigators have made efforts to identify antecedent conditions in the home which might be responsible for differences in children's personality as well as cognitive development. Thus democratic homes (I, 2), maternal acceleration (18), and a warm, positive family atmosphere (17) have been reported to increase the rate of of children's intelligence, especially verbal ability. Results of investigations of the effect of institutionalization and prolonged hospitalization of infants, summarized by McCarthy (15, pp. 584-585), uniformly indicate retardation in language development. On the other hand, there has been suggestive evidence that certain conditions favor disproportionately the development of verbal ability and possibly impede the development of nonverbal skills, like numerical and spatial ability. Suggested as antecedents for such differential development in favor of verbal ability were growth restricting childrearing practices (24), such as parental overlimitation and excessive control, maternal overprotection (14), on verbal accomplishment (13), and a demanding discipline with emphasis on academic achievement (1r). Similarly, overanxious discipline (11) and tense parent-child relationships (io) were postulated to be responsible for low nonverbal, especially spatial, ability in children. While the consistently found superiority of boys over girls in spatial ability may be considered innate (5, 6, 8, 9), there has been suggestive evidence that this may be the result of differences in roles assigned to males and females in our culture (4, 7, 19, 22). Most of these studies, while yielding intriguing leads, failed to measure children's verbal and nonverbal abilities with relatively pure tests. Also, these studies investigated primarily parents' present-day childrearing behavior and did not attempt to investigate the very early mother-child rela-