Emergent properties of Japanese verbal inflection

Abstract

This study investigates how speakers of Japanese mentally represent and process verbal inflection. Japanese exhibits an agglutinating inflectional typology, however, morpheme boundaries are not always transparent and there is considerable stem allomorphy. Furthermore, there are no bare stems. The stems of consonant-stem verbs never appear in isolation because they are unpronounceable phonotactic violations. This feature of Japanese presents two problems to a rule hypothesis of verbal processing, whereby regular verb forms are produced by the combination of stem and inflection: 1) How do Japanese speakers compute stems? 2) Are speakers of Japanese able to mentally represent and process forms that they cannot pronounce? An alternative to a rule hypothesis is Bybee's Schema Model, which allows for the mental representation of fully inflected forms. In this study, Schema Model and rule hypothesis predictions about errors and productivity are compared. First, it is shown that the native analysis of inflection reflects phonological and orthographical constraints consistent with the notion that native speakers do not segment verbs into stems and endings. Second, results of a search of the Miyata database show that: 1) Japanese children under three years of age do not overregularize. 2) Most verb errors are stem errors. 3) There are many more errors with regulars than with irregulars. 4) There is no default error pattern. Third, a written test asks fifty adult native speakers and fifty adult instructed (L2) learners to choose appropriately inflected nonce forms. The learners outperform the native speakers. 76% of the learner group responses are correct, but only 53% of the native group responses. No evidence is found that learners or natives make use of a default rule. Finally, an oral response, nonce probe test with Japanese children (five and six years of age) finds that the children cannot productively inflect novel verbs. It is concluded that the lack of default error patterns and the inability of native children and adults to productively inflect novel verbs is best explained by a Schema Model whereby inflectional morphology emerges from use (including verb type and token frequency) and not from the manipulation of abstract verbal stems.