ERP Responses to Violations in Japanese Verb Conjugation Patterns

要旨

ERP Responses to Violations in Japanese Verb Conjugation Patterns Yuki Kobayashi (ykobayashi@ecs.c.u-tokyo.ac.jp) Center for Evolutionary Cognitive Sciences, The University of Tokyo 3-8-1 Komaba, Meguro-ku, Tokyo, JAPAN Yoko Sugioka (sugioka@sfc.keio.ac.jp) Faculty of Economics, Keio University 4-1-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, JAPAN Takane Ito (ito@boz.c.u-tokyo.ac.jp) Graduate School of Arts and Sciences, The University of Tokyo 3-8-1 Komaba, Meguro-ku, Tokyo, JAPAN Abstract same mechanism can deal with both “regular” and “irregular” inflection. Few studies have been conducted on Japanese in this context: a notable exception is Hagiwara et al. (1999), who argue for the Dual-Mechanism processing in Japanese derivational morphology. The present study places its focus on the processing of Japanese inflectional morphology, which has so far attracted little attention (cf. Vance 1991, Yu et al. 2011). ERP (Event Related Potential) measurement using the violation paradigm of Japanese verb conjugation was conducted in order to investigate the mental and neural mechanisms involved in the processing of different conjugation patterns. A LAN-like component followed by a P600 was elicited for the anomaly of using a tense-bearing form with the negative ending, while only P600 was observed for the anomaly of using an infinitive form in the same environment. The non-application of morpho-phonological changes of verb roots (“onbin”) yielded an N400 component and a P600. The P600 components observed in all types of errors reflect the cost of processing morphological and/or syntactic anomalies, while the difference in the negativities suggest that two different mechanisms of rule-based computation and lexical memory are involved in the processing of Japanese verb conjugation. ERP Components Related to Language Processing Keywords: verb conjugation; inflection; N400; LAN; P600; Dual Mechanism Model; rule; memory Introduction The aim of the present study is to elucidate the mental and neural mechanisms involved in the word-level language processing, exploiting the technique of ERP (Event Related Potential) measurement. More specifically, we investigated the processing of Japanese verb conjugation by recording ERP responses to different types of errors in the conjugation patterns. In doing so, we addressed the question of whether verb inflection involves more than one mechanism of processing in a language typologically different from European languages. There has been heated debate since 1980’s concerning the mental mechanisms involved in word-level processing, with the focus on inflectional morphology in European languages. On the one hand, Dual Mechanism Model (Pinker 1999, Ullman 2001, among others) argues that two qualitatively different mechanisms, namely, rule-based computation and associative memory, are involved; English “regular” -ed past forms, for instance, are dealt with by the former, while “irregular” forms like sing/sang are by the latter. On the other hand, Single Mechanism Model (Joanisse and Seidenberg 1999, among others) contends that one and the Three components, N400, LAN, and P600 are known to be related to language processing. The N400 is a negativity which peaks at around 400 ms after the onset of stimuli with wide, often posterior-centered distribution (Kutas and Hillyard 1980). The component is known to reflect semantic or pragmatic anomaly. It is likely to be related to the search of lexical memory as well, since its amplitude is known to reflect the frequency of the stimulus word (Kutas & Federmeier 2000), and it is observed in word-specific argument structure violation, namely, anomaly with respect to lexical information (Friederici & Frisch 2000, Friederici and Meyer 2004). The LAN (Left Anterior Negativity) component is also a negativity observed at around 300-500 ms after the onset of stimuli: it is distinguished from the N400 in its distribution, which is limited to the left anterior region. This compo

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