Correlating cognitive effort and noun role in spoken Japanese

Abstract Models of language processing assume that the cognitive cost to integrate a noun with a verb depends on the distance between the noun and the verb. Such models predict that subjects require more cognitive effort than objects in SOV languages, such as Japanese. This study tests that prediction by investigating apparent cognitive effort differences in topic, nominative, accusative, dative, genitive, and predicative noun usage, using two corpora of spoken Japanese. A cognitive effort index score was determined for each text in the two corpora. The correlations between index scores and usage rates for each grammatical role were determined. Accusative, dative, and genitive noun usage significantly correlated with cognitive effort index scores, but topic, nominative, and predicate noun usage rates did not. These results suggest that the cognitive cost of noun integration depends not only on distance but also on the grammatical role of the noun.