Children's gradual acquisition of singular and plural

By two years of age children are using singular and plural words appropriately in their speech (Brown 1973), yet it is unclear whether their early representations are adult-like. It is not known how and when children develop the understanding that a word such as cats is composed of the lexical root cat and the plural morpheme -s (i.e., cat+s). The aim of this thesis was to therefore to explore some of the factors that potentially affect young children's understanding of the marking of nominal number in English. The studies presented in chapters two and three examined children's early comprehension of singular and plural using a novel-word Intermodal Preferential Looking task (Kouider, Halberda, Wood & Carey, 2006). In chapter two, the results found that 24-month-olds had an understanding of plural morphology that was limited to the voiceless plural allomorph /-s/ (e.g., cat + /s/), which is longer in duration and more perceptually salient than the voiced allomorph /-z/ (e.g., dog + /z/). However, the results presented in chapter three suggested that perceptual salience was not the only factor to play a role in children's acquisition of plural morphology, as 36-months-olds, but not 30-month-olds, were found to understand the most perceptually salient syllabic allomorph /-əz/ (e.g., bus + /əz/). The studies presented in chapters four and five examined pre-schoolers' understanding of singular and plural using a novel-word forced choice task. In chapter four, the study found 3- to 5-year-olds' comprehension of novel plurals, yet not novel singulars, improved with age. The study in chapter five examined children with hearing loss, which is known to affect children's acquisition of English plural and tense inflections, likely due to difficulty perceiving fricatives (Koehlinger, Owen Van Horne, & Moeller, 2013). Overall, the children with hearing loss were no better than chance at identifying novel plurals and singulars. However, comprehension of novel plurals improved with age. The thesis concludes with a discussion of the acquisition of morphological representations more generally.