Infants of 18 and 24 months acquiring English were tested in a preferential looking task on their ability to detect ungrammaticalities caused by manipulating a single function word in sentences. Infants heard grammatical sentences in which the determiner "the" preceded a target noun, as well as three ungrammatical conditions in which "the" was…

Patterns of speech from lower socioeconomic status mothers to their infants were analyzed to determine correlations with infant risk of mental retardation. Measures of maternal language included sentence form, amount of speech, and syntactic complexity. The proportion of imperatives was positively correlated with risk status and negatively…