Chapter 1. The development of third person singular present form -s
Verb semantics or input frequency?
Addressing two hypotheses, the Aspect Hypothesis (Andersen & Shirai 1994; Shirai & Andersen 1995) and the Verb-Island Hypothesis (Tomasello 1992), this study analyzed whether the acquisition of third person singular present -s (3S) follows the same path as other tense-aspect markers, such as -ing, past, whose acquisition is influenced by the verb semantic properties, or its acquisition is affected more by input frequency. The present study analyzed three children’s longitudinal data from CHILDES database (MacWhinney 2000) and investigated the developmental characteristics of 3S from three perspectives: the percentage of 3S co-occurring with stative verbs, the frequency correlation of mother’s input and child’s production, and the data comparison with the past tense marker. The results show that the children’s acquisition of semantically motivated morphemes, (i.e. past tense), was more affected by verb semantic properties than input frequency, supporting the Aspect Hypothesis. However, the acquisition of formally motivated features (i.e. 3S), was more affected by input frequency, supporting the Verb-Island Hypothesis.