Cognitive Development in Infants of Different Age Levels and from Different Environmental Backgrounds: An Explanatory Investigation.

Abstract

Recent years have seen a growing interest in the study of the relation ship of environmental stimulation to intellectual development. In particular, with the establishment of programs such as Head Start, the importance of early experience (defined here as the first two years of life) has been in creasingly stressed. In good part, this emphasis on experiences during the early years and their effects upon intellectual functioning is based on previous evidence relating early experiences to the growth and development of sensory structures (Riesen, 1961, 1965), central nervous system physi ology and biochemistry (Levine, 1962; Haywood & Tapp, 1966; Rosen zweig, Krech, Bennett, & Diamond, 1968), curiosity behavior (Sackett & Cory, 1965; White & Castle, 1965; White & Held, 1966; DeNelsky & Den enberg, 1967a, 1967b; Rubenstein, 1967), language (Irwin, 1948, 1960; Hess & Shipman, 1965), emotionality (Denenberg, 1964, 1967), and learning (Denenberg, 1964, 1967). The relevance of early experience for intellectual progress has been seen primarily in studies of orphanage-reared infants, who typically show decrements in measured intellectual functioning (Pasamanick, 1946; Gilliland, 1949; Dennis & Najarian, 1957; Kohen-Raz, 1968), and in successful attempts to modify early intellectual development through specific remediation measures (Skeels, 1936, 1938, 1966; Kirk,