Russian case inflection: Processing costs and benefits

Mechanisms underlying the processing and storage of morphological case are still debatable in psycholinguistics. The key questions concern the nature of the special status of the nominative, the homogeneity\slash heterogeneity of oblique case forms, the impact of case syncretism and paradigmatic relations on nominal processing and the organization of the mental lexicon. We investigate these issues turning to Russian nominal processing. We performed two experiments with feminine and masculine nouns in different cases (experiment 1: nouns in singular, experiment 2: nouns in plural) using the visual lexical decision task. In this task, we measure the speed and accuracy with which the participant classifies sequences of letters as words or non-words. Evidence from both experiments indicates that differences in processing exist not only between the nominative and the other case forms, but also among the obliques. Experiment 1 points to the influence of wordform and exponent ambiguity, while experiment 2 reveals effects that are specific for case per se. We discuss the role of zero vs. overt phonological form, grammatical features, (non-)accidental homonymy, context, frequency, inflectional and relative entropy in case recognition.