Parents' report of vocabulary and grammatical development of African American preschoolers: Child and environmental associations

This study examined how child and family factors affect individual differen ces in the language development of African American children between 18 and 30 months of age. Participants were 87 African American children, primaril y from low-income families. Children's vocabulary and grammatical skills we re assessed at 18, 24, and 30 months of age using the short form of the Mac Arthur Communicative Development Inventory (CDI), a standardized parent rep ort tool. Standardized language tests were administered repeatedly between 1 and 3 years of age. Results showed that children's vocabulary and utteran ce length grew linearly over time between 18 and 30 months of age. Children from more stimulating and responsive homes were reported to have larger vo cabularies, to use more irregular nouns and verbs, and to use longer uttera nces, in addition to having more rapid rates of acquisition of irregular fo rms and longer utterances over time. Girls used longer utterances than boys and more irregular forms. Girls also had larger vocabularies in a secondar y analysis that eliminated children whose parent report of their vocabulary was substantially lower than children's scores on a standardized language test. There are indications that some parents may be under-reporting their children's early vocabulary and grammatical development, with a high propor tion of the parents reporting their child's 30 month vocabulary and grammat ical development as being at or below the 10th percentile according to the CDI norms.