What lexical acquisition has to say about a non-lexicalist architecture of grammar – and vice-versa

Abstract

Distributed Morphology (DM) predicts that the units of syntactic derivation are smaller than words. This paper explores the implications of this prediction for language acquisition research and questions if DM is descriptively and theoretically sound when faced with acquisition phenomena. We first introduce independent evidence supporting sub-word units in acquisition: results from a computational model of lexical acquisition show that slightly more morphologically complex input data, such as Brazilian Portuguese when compared to English, cause a substantial decrease in the model’s performance; children’s early productions when acquiring polysynthetic languages reveal they are attempting to find these languages’ morphological units, instead of relying on chunks of non-analysed material; and words are shown to lack explanatory power in describing language acquisition in terms of storage, bootstrapping, or production. We then bridge the gap between DM and earlier proposals for the identification of words and formal features, briefly outlining a strategy for acquiring morphemes. Finally, we present accounts for two prevalent phenomena linked to language acquisition through the lens of DM: the overregularisation in acquiring irregular verbs, a step observed in children acquiring different languages; and the Brazilian Portuguese verbal paradigm shift, an example of morphological diachronic change. Our findings support the non-lexicalist derivation of words, highlighting that words are incompatible with acquisition from multiple perspectives. This suggests that understanding language acquisition benefits from considering the smaller, morpheme-based units predicted by Distributed Morphology.

Keywords

• lexical acquisition
• Distributed Morphology
• overregularisation
• diachronic change