Title: Disassociating maturation and language development
Description: Typically language development in children closely coincides with development in many other areas. This makes it difficult to determine whether observed correlations are coincidental or causal in nature. The three studies presented here explore these relationships by looking at two populations of learners who are delayed in exposure to English, but not in other areas of maturation--internationally adopted children and deaf children with cochlear implants. The first study tracks the earliest stage of English acquisition in fourteen preschoolers adopted from China. The study finds that despite the cognitive advantage, these children show the same relationships between vocabulary size and the grammatical complexity of speech that are observed in infant learners and they also show similar vocabulary composition. The second study examines the patterns of lexical and syntactic development in 3 to 9 year old cochlear implant (CI) users. The CI users show a general advantage in vocabulary ability relative to syntax and show a pattern of syntactic development which appears to be consistent with their perceptual limitations.

The third study compares English language abilities and theory of mind (ToM) performance of internationally adopted children who are passed the typical age of ToM mastery but have limited English skills. Current language ability is found to be critical to performance on standard verbal ToM tasks and also influential on visually presented ToM tasks. This group of studies demonstrates that many of the patterns within language development and between language and ToM development remain even when maturational constraints are removed. Rate of acquisition is a notable exception, mature child learners are able to proceed through the typical stages of language development more rapidly than infant learners.