a1 University of Memphis
Acquisition of regular inflectional suffixes is an integral part of grammatical development in English and delayed acquisition of certain inflectional suffixes is a hallmark of language impairment. We investigate the relationship between input frequency and grammatical suffix acquisition, analyzing 217 transcripts of mother–child (ages 1 ; 11–6 ; 9) conversations from the CHILDES database. Maternal suffix frequency correlates with previously reported rank orders of acquisition and with child suffix frequency. Percentages of children using a suffix are consistent with frequencies in caregiver speech. Although late talkers acquire suffixes later than typically developing children, order of acquisition is similar across populations. Furthermore, the third person singular and past tense verb suffixes, weaknesses for children with language impairment, are less frequent in caregiver speech than the plural noun suffix, a relative strength in language impairment. Similar findings hold across typical, SLI and late talker populations, suggesting that frequency plays a role in suffix acquisition.
(Received March 26 2010)
(Revised January 22 2011)
(Accepted September 15 2011)
(Online publication December 13 2011)
[*] This work was supported by a Department of Energy Computational Science Graduate Fellowship awarded to the first author. We thank Sarah Lowder, Rick Dale, the research teams and participants who contributed data for the Conti-Ramsden and Weismer CHILDES corpora, the CHILDES project, the R project, and the anonymous reviewers of this article.