The goal of this dissertation project is to deepen our understanding of how language acquisition is related to the development of other cognitive abilities. Children seem to learn their first language effortlessly and rapidly. By three years of age, most children appear to speak in fully grammatical sentences and are able to learn up to ten new words every day. How language acquisition happens continues to be one of the driving questions in language research and an important one for all fields related to early childhood development. Knowing how children acquire a first language is crucial for understanding how a second language is learned and therefore is important for understanding how to more quickly integrate immigrant children into English-language schools in the US. This knowledge will also allow us to improve our toolkits for helping children who are challenged by language delays or by language impairments associated with developmental disorders such as Specific Language Impairment, Down Syndrome, and Autism Spectrum Disorders.
This project looks at the development of subject-verb agreement, which is the element of grammar that allows us to distinguish between "The sheep grazes" and "The sheep graze", for example. Research to date suggests that children can produce subject-verb agreement accurately before they comprehend it. This appears to be a paradox because it is generally assumed that children understand language structures before they begin to produce them in speech. This study will investigate how English-speaking preschoolers' brains process this grammatical feature, and how well children produce and comprehend it, to develop a model of the relationship between these abilities as they develop between the ages of 3 and 5 years. Children's number skills will also be measured to look at whether their conception of the number line influences how well they comprehend the singular-plural distinction of subject-verb agreement, which is marked on English regular verbs by "-s" or no "-s". This dissertation grant will support the first study to investigate this question with a comprehensive approach that takes into account neural processing, production and comprehension of the sentences, as well as cognitive maturational factors, including maturation of numeracy skills. The results of this study will help us to understand grammatical development in English-speaking children and validate an approach to research on child language development that can be extended to other languages in which the same apparent paradox has been observed, including, German, French, Spanish, and the Bantu language Xhosa.
