Constraints on Phonological Development
One of the issues we have been investigating is the nature of the constraints on the shape of children’s early Prosodic Words. This appears to be depending on the distribution of word and foot structures found in the target language. Recent research has also examined the development of syllable structures. Some of this work finds that coda consonants are more likely to be produced in stressed and final syllables, both of which exhibit increased duration, suggesting that this facilitates the articulation of more segments. Other research has focused on the acquisition of word-final clusters, raising questions about the competing contributions of frequency, morphology, and structural/sonority/articulatory factors in predicting the course of cluster acquisition across languages. These issues are currently being explored acoustically, examining children’s early representation of feature cues to segmental contrasts.

Interactions at the Phonology/Morphology Interface
One of the classic problems in language acquisition is variability in the production of grammatical morphemes. We have been investigating the possibility that much of the within-speaker variability in morphological production can be understood in terms of prosodic (contextual) constraints. Some of our research has shown that English learners are more likely to produced grammatical morphemes like the 3rd person singular –s in phonotatically simpler contexts, especially at the ends of phrases. Other research shows that French, English, and Sesotho learners are more likely to first produce determiners and noun class prefixes with monosyllabic nouns, and only later with nouns containing 2 or more syllables. These findings suggest that grammatical morphemes may be acquired earlier in contexts where they are prosodically licensed, pointing to a closer link between the acquisition of phonology and morphology than syntacticians typically assume.

Syntactic Generalization
We have long been interested in how and when children begin to make syntactic generalizations. Some of this research has been carried out in Sesotho, where the high frequency of passives appears to facilitate earlier acquisition of this construction than in English. On the other hand, Sesotho-speakers also exhibit generalization to low-frequency double-object applicatives, where word order is influenced by animacy rather than thematic role. Recent work on English dative shift also shows that 3-year-olds generalize new syntactic frames to novel verbs, and current research is examining syntactic generalization with intransitives. These findings point to an early ability for syntactic generalization, and the possibility of early syntactic priming.

The Nature of the Input and Implications for Learnability
The starting point for much of our research is determining the nature of the input children actually hear. This involves detailed study of child-directed speech corpora. Armed with this information we can better address the nature of the learnability problem. Much of this research examines the nature of the input at different levels of structure (i.e., syntactic, lexical, morphological, segmental, acoustic/phonetic) and makes predictions about the course of development of certain structures crosslinguistically. This is complemented with probabilistic modeling of the learning process, in an attempt to discover what types of procedures learners may use in solving the problem of language learning problem.

Research Opportunities
Graduate students or postdocs interested in pursuing any of these areas of research should contact Katherine Demuth. Undergraduates interested gaining research experience, or in summer UTRA research fellowships, should inquire by December 1.