Study On The Cognitive Mechanism Of Chinese Polyphones' Phonological And Semantic Information In The Sentence Context

Chinese language cognition is an important branch in the field of cognitive neuroscience. Till now, the study on Chinese polyphones is few, and their mechanism remains unclear. Therefore, the main work reported in this study is the employment of event-related potential(ERP) with high temporal resolution and functional near-infrared spectroscopy(NIRS) with high spatial resolution to investigate processing of phonological and semantic information on polyphones in multi-modal sentence context.During the experiment, polyphones in Chinese are regarded as the critical characters placed at the final position of sentences, and the characters and speech signals are presented simultaneously. The materials are divided into four conditions according to the relations between polyphones' pronunciations and the context: pronunciation is correct and matches the context(P+M+); pronunciation is correct but mismatches the context(P+M-); pronunciation is incorrect but matches the context(P-M+); pronunciation is incorrect and mismatches the context(P-M-). In our study, all the critical characters under the four conditions induce P200, N400 and late positive shift. The results indicate that P200 is relevant to extract phonological information at an early stage of language comprehension, which is influenced by the matching degree between actual speech and expected phonology. Under P+M+, P+M-, P-M+, P-M- conditions, N400 are evoked, whose amplitude increases, that might be related to the discrepancy between actual speech and semantic prediction. Moreover, the late positive shift may reflect the re-analysis of phonological or semantic information when the visual information mismatches the audio information. The study using NIRS reveals that the concentrations of oxygenated hemoglobin(HbO2) will increase and the concentrations of deoxygenated hemoglobin(Hb) will decrease when there is a discrepancy between the actual critical character and the expected one. The activations distributed on the left and right inferior frontal gyrus, and the left middle temporal gyrus which are consistent with the results of topography in ERP. In summary, the present study with two experiments using ERP and NIRS confirms the polyphones' mechanisms from temporal and spatial dimensions, exploring that phonological information is important for characters' cognition, and the results are basically consistent in both dimensions.