Neural Distinction between Chinese Nouns and Verbs in the Grammatical Context: An ERP Study

Abstract

Many current researches in neurolinguistics focus on the different possible neural representations of nouns and verbs.Evidence from neuropsychological and neuroimaging studies suggests different neural representations of nouns and verbs in Indo-European languages.Specifically,verbs are represented in the frontal region,while nouns are represented in more posterior brain areas.This is consistent with the results of electrophysiological studies.In contrast to other Indo-European languages,Chinese is characterized by the lack of inflectional morphology.Some investigators argued that nouns and verbs in Chinese are not dissociable with regard to grammatical classes but rather are differentiated by their semantic properties.The current study aims to investigate whether noninflectional nouns and verbs in Chinese could be dissociated at the neural level and whether the dissociation reflects their grammatical roles. All the nouns and verbs used in the experiments were all words that were not characterized by inflectional morphology.There were three sets of stimuli used in the experiments:(1)disyllabic unambiguous nouns,(2)unambiguous verbs,and (3)noun-verb ambiguous words.These stimuli were combined with a priming word to construct two contrastive phrase contexts,namely,noun-predicting(e.g.,"yi Q +_") and verb-predicting(e.g.,"bu M +_").The subjects were asked to decide whether the presented phrase represented a legal or illegal phrase.ERPs in response to the three sets of stimuli in different contexts were recorded.The ERPs were then analyzed using a repeated-measures ANOVA. We observed significant ERP differences between nouns and verbs in intervals of 145~225ms,250~400ms,and 450~650ms.Unambiguous nouns elicited a larger P200 than did unambiguous verbs.When the context completely matched their role,unambiguous verbs elicited a larger N400 and a smaller P600 than unambiguous nouns. Similarly,ambiguous words used as nouns elicited a larger P600 than did ambiguous words used as verbs. Our results do not support the claim that nouns and verbs in Chinese are not dissociable in terms of grammatical classes.On the contrary,the results demonstrated clear ERP responses that reflect a grammatical process.We argue that although the Chinese language lacks inflectional morphology,grammatical features are embedded in nouns and verbs and function regardless of whether there are explicit grammatical signs in these words.Grammatical features play an important role in the neural processing of Chinese nouns and verbs.