Research

In the Language Development Lab we investigate many different facets of language development in children, with the goal of understanding how typically developing children learn from exposure to the language spoken around them and addressed to them by adults. The questions we explore range from how infants begin to figure out what sequences of sounds in their language are words, what the words mean, and how words combine to form grammatical sentences.  Our current studies involve monolingually exposed infants, as well as infants acquiring multiple languages.

The most immediate motivation for our research is to better understand the cognitive mechanisms that support the rich and uniquely human capacity of language acquisition, including the similarities and differences between these mechanisms and those that support learning and cognition in other domains, and other species.  The broader significance of our research is in gaining insight into what happens when normal language acquisition is impaired.

Below is a brief selection of some of the recent and ongoing studies with infants and children in the Language Development Lab. Although the primary focus of the lab is language development in infants and young children, our methods also involve experiments with adults, typically using minature aritifical languages that mimic certain properoties of natural languages.  These experiments yield insights into the kind of learning processes humans possess that may be relevant to language learning, and they also inform us as we design experiments for infants and young children. In addition, we use computer analyses to test our theories of language acquisition.

In our studies, infants listen to words or look at video displays, and we monitor what they like to listen to or look at most. Toddlers participate in play sessions with the experimenter which involve new, interesting toys or objects which we sometimes describe to the children using new words, and we see what they think the words mean.

Infants begin to show knowledge of the structure of their language by the time they are 12 months old.  Even though they are just beginning to produce their first words at that age, they already recognize some grammatical patterns in their language.  When and how do they start learning how the grammar of their language works?

In English and many other languages, a questions and statements order words differently.  For example, compare Anna likes chocolate with What does Anna like?: The question contains words that the statement version doesn’t have, and the words that occur in both sentences occur in different positions.  Because staements and questions have different structures, children learning a language like English must figure which utterances are statements and which are questions in order to figure out the rules for forming each sentence type.  We are exploring how early and by what means, child learners are able to make this critical distinction.  So far, we have found that by the time infants are just 12 months old (when they have barely started to walk and to produce their first words), infants can differentiate certain types of questions from statements.  Our ongoing experiments are probing whether this ability is present even earlier.

Some of the studies in the lab investigate infants’ developing knowledge of English (see above).  However, sometimes it is useful to use simple artificial languages that have grammars that we design to resemble real languages in particular ways.  We expose infants to brief passages of the language, and test what kinds of patterns they are able to detect.  In one set of studies, we use such languages to test theories about when and how infants are able to learn that certain words in a sentence are related, as in English where the verb form depends on the subject of a sentence (e.g., they walk but she walks).  From studies using artifiical languages we gain insights when and how infants can learn similar kinds of properties of real languages.

An important part of learning the grammar of a language is learning the grammatical categories of words, such as noun and verb.  It appears that infants between 12 and 18 months can use the grammatical structure surrounding an unfamiliar word to figure out its category.  We have designed experiments using artificial languages as well as English to investigate what kinds of information infants and young toddlers use to figure out the cateogries of words.