中文詞類訊息處理的腦側化現象：事件相關電位研究

Brain Asymmetry in Syntactic Processing of Word Class in Chinese: An ERP study

陳旻昕(Min-Hsin Chen)

指導教授 ： 李佳霖

國立臺灣大學/文學院/語言學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201603053

摘要

過去研究普遍認為人類處理句法的能力側化到左腦，近期研究則指出，右腦某些程度上也擁有同樣的能力。但對於句法資訊在同樣的句法單位但語意程度不同的語言中，右腦處理句法訊息的方式尚未有定論。因此，本篇論文以中文為媒介探討 (1)中文詞類訊息處理的歷程是否和英文的腦側化現象一致 (2)不同處理方式反應兩腦間何種合作和抑制關係。
本篇研究使用事件相關電位(Event-Related Potential, ERP)技術，收集28位慣用右手且擁有右利家族史(FS-)的年輕人之腦波。研究包含四個實驗，實驗一至二為腦波實驗，試圖回答研究問題一；實驗三至四則是針對研究問題二設計的行為實驗。實驗一探討中文詞類訊息處理的語言歷程，通順或不通順的中文詞組會呈現在螢幕正中央供參與者閱讀。實驗結果成功複製文獻中句法合理性的效果(grammaticality effect)，包括300-600毫秒的語意衝突效果(N400 effect)和600-1100毫秒的句法衝突效果(P600 effect)。實驗二使用分視野實驗方法(divided-visual field paradigm)，記錄目標詞呈現在左視野或右視野時，左腦和右腦優勢處理句法的歷程，結果顯示中文詞類訊息的處理歷程和英文一樣側化到左腦。
過去研究在解釋語言腦側化背後的神經機制時，指出機制下兩腦間的溝通關係可能為單側抑制關係(左腦對右腦的抑制)或者雙邊合作關係。實驗三和四，分別為雙向旁側抑制作業(bilateral flanker task) 和語意配對測驗(word-matching task)，測試參與者兩腦間的單側抑制和合作整合能力。在雙向旁側抑制作業中，螢幕上的左右視野會分別出現指向相同或不同的兩個箭頭。參與者必須注意被指示的其中一側，回答該側箭頭的指向，同時抑制對異側箭頭的反應。在語意配對測驗中，參與者在螢幕上閱讀呈現在單側或對側的兩個中文單字，並判斷兩者的語意匹配程度。結果發現語言腦側化的程度和兩腦間的合作關係(以語意配對測驗上的表現為指標)呈現顯著負相關，而和兩腦間的抑制關係(以雙向旁側抑制作業的表現為指標)較無相關，表示腦側化程度越高者，在雙邊合作的作業上越容易受到干擾。
綜觀腦電波和行為實驗的結果，本篇研究不但確立中文詞類訊息處理的腦側化現象，也顯示在語言腦側化程度較高的年輕人當中，兩腦合作關係和腦側化程度相關，並反映出大腦雙邊合作和訊息整合的緊密關係。

關鍵字

句法處理 ； 中文詞類訊息 ； 分視野實驗 ； 語言腦側化現象 ； 兩腦間抑制關係 ； 兩腦間合作關係

並列摘要

While recent evidence suggests that the right hemisphere (RH) is not as insensitive to syntactic information as previously thought, the extent to which the RH can engage combinatorial syntactic processes like the left-hemisphere (LH) does across languages that are lexically coded to different degrees is still poorly understood. The present study targeted Chinese native speaker to investigate (1) whether similar qualitative difference between two hemispheres during syntactic processing of word class information previously found in English can also be found in Chinese and (2) what kind(s) of the underlying mechanisms or inter-hemispheric communication are implied for such functional asymmetry of language.
We conducted four experiments collecting data from 28 right-handed young adults without familial sinistrality background (FS-) to research on these topics, the first two being ERP experiments seeking answer for question (1) and the last two behavioral tasks attempting to answer question (2). Experiment 1 investigated word class violation with central presentation, in which participants read either match or mismatch word pairs presented at the center of the computer screen. The results successfully replicated previous findings by showing grammaticality effects indexed by N400 (300-600 ms) and P600 (600-1100 ms). Experiment 2 then investigated word class violation with divided-visual field presentation, in which the targets were presented either in left-visual field or right-visual field, assessing the LH- and RH-biased responses respectively. The results showed a left-lateralized P600 effect, similar to what was reported in the English literature.
As suggested by past studies that interhemispehric communication of coordination between two hemispheres or unilateral inhibition (from LH on RH) to be the most possible mechanisms underlying the functional asymmetry of language, we designed experiment 3 and 4, bilateral flanker task and word-matching task, to assess the ability of interhemispheric inhibition and coordination for each participant. In the bilateral flanker task participants saw pairs of arrows presented across left and right visual fields. The arrows were either congruent or incongruent in direction. They were asked to attend to one of the visual fields and judge for the direction of the target arrow while ignoring the distractor from the other visual field. In the word-matching task, participants were shown two Chinese one-syllable words either bilaterally shown to each visual field or unilaterally within a same visual field. Participants were asked to make semantic relatedness judgment. The results revealed a negative correlation between the degree of language lateralization and the inerhemispheric coordination ability (assessed using the word-matching task), but not interhemispheric inhibition ability (assessed using the bilateral flanker task), suggesting that larger degree of language lateralization reflects greater interference between hemispheres during tasks requiring bilateral integration and thus results in worse interhemispheric coordination. Combining the results from both ERP experiments and behavioral tasks, the present findings established the functional lateralization patterns of brain responses during word class processing in Chinese. In addition, the present findings demonstrated that among young adults with stronger lateralization pattern in language processing, the degree of lateralization is related to interhemispheric coordination, pointing out the close relationship between parallel processing and bilateral integration.

並列關鍵字

syntactic processing ； word class information ； split-visual field paradigm ； hemispheric differences ； language lateralization ； interhemispheric inhibition ； interhemispheric coordination

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