Pronoun case overextensions and paradigm building.

Pronoun case errors, or overextensions, like *me want it are characteristic of English child language. This paper explores a hypothesis that the morphological structure of a pronoun influences the pattern of these errors. The Language Acquisition Device (LAD) attempts to analyse English pronoun case forms into stems and affixes, but cannot because of their irregularity. Nevertheless the LAD extracts a phonetic core for each pronoun (e.g./m-/ for the 1st sg.,/h-/ for the 3rd masc. sg.). The phonetic core blocks the overextension of suppletive nominative forms like I and she. This hypothesis predicts strong differences in the frequency and types of errors between pronouns with suppletive nominatives and those without. Evidence for this hypothesis was found in a transcript database of twelve children, with data collected in one hour samples every month from 1;0 to 3;0. 20,908 pronouns were examined, 1347 of which were errors. Statistical analyses of these data provide support for this hypothesis.