Functional morphemes in Japanese mothers’ speech input to their infants

In Japanese, joshi or functional morphemes attached to nouns are often omitted in colloquial Japanese speech, while verbs never occur without functional morphemes, i.e., verb suffixes. The present study explored how frequently Japanese-learning infants hear joshi (or noun particles) and verb suffixes in the speech input. Twenty mothers’ speech to their infants aged 10 and 15 months was analyzed. The results showed that more than half of the noun tokens in mothers’ utterances were followed by no particle, and that the most frequent particle ga followed 12% of the noun tokens. Verbs were followed by a limited number of verb suffixes at an extremely high frequency, and the most frequent verb suffix -t-te-iru occurred more frequently than the most frequent noun particle ga. The occurrence of the remaining verb suffixes was quite infrequent. Influences of such distributions of functional morphemes on children\u27s learning of syntactic categories of nouns and verbs were discussed