Patterns of early lexical and cognitive development in premature and full-term infants.

The linguistic and cognitive development of 26 premature and 27 full-term infants was studied longitudinally over the first 3 years of life. Infants in the premature population included 12 who were below 1500 g in birthweight and an even larger number with "at risk" signs. Language samples were collected in the home approximately every other month, the children were given experimenter-designed tests periodically, and mothers were asked to keep diaries of their children's lexical development. The children were given standardized tests as they exited the study. Cognitive development was also measured periodically. The patterns of lexical and cognitive development of the prematures did not differ markedly from those of full-term infants. There were no significant differences between the prematures as a whole and the full-term infants on standard language test measures as they exited from the study. There were significant differences between the very low birthweight and full-term infants on two of the exit measures. However, the performance of the very low birthweight infants was well within the range of normal on these two measures. The nature of the study and the factors that might have led to lack of differences between the two groups are discussed.