Researchers in the Language Program investigated the nature of language development in children from 2- to 13-years-old, exploring the acquisition of language contrasts in sound patterns, in word formation, in sentence structure and in sentence interpretation, both in typically developing children and in children developing bilingually. The findings of our studies have provided a much more comprehensive understanding of preschoolers’ language abilities in each of these domains, and the factors that influence development over time. Professors Stephen Crain and Rosalind Thornton, and Dr Loes Koring were invited to provide a critical assessment of the biolinguistics approach to celebrate the 50th anniversary of Eric Lenneberg’s foundational work (Crain, Koring, & Thornton, 2017). Fifty years ago, Lenneberg’s The Biology of Language advanced a new approach to language acquisition, now called the ‘biolinguistics’ approach. Although Lenneberg’s proposal was mostly based on impressionistic observations, there is now much experimental research on the acquisition of language. Professor Noam Chomsky comments, “Crain, Koring and Thornton develop a comprehensive and careful comparison of the two major approaches to language acquisition, the biolinguistic and usage-based approaches, and identify critical issues on which they differ in their predictions. They then demonstrate that experimental studies of language acquisition uniformly rule in favor of the biolinguistics approach […]. A very valuable contribution to the study of the nature of human language and how it is uniformly acquired.”
Another long-standing issue in child language is why children are delayed in their use of the syllabic plural allomorph –es, as in bus+es (Brown, 1973). It was unclear whether the delay was due to the lack of a grammatical representation (e.g., taking the ‘s’ at the end of bus as a marker of the plural (Berko, 1958)), or due to articulatory problems in producing fricative-schwa-fricative sequences, or because this form of the plural requires an unstressed additional syllable at the end of the word. An elicited imitation study indicated that both allomorphy and utterance position influenced the use of plural morphology: 2.5-year-olds had more problems in general producing syllabic plurals as compared to segmental plurals (e.g., cat+s), and these problems were especially acute for words in utterance medial position (Mealings, Cox, & Demuth, 2013).