研究生姓名 : 黎引真
學年度 : 101
論文題目 : 以行為及腦造影證據探討英文字音及字形相似效果對中英雙語使用者之短期記憶的影響
英文論文題目 : Behavioral and fMRI investigations on the effects of phonological and visual similarity of English words on short-term memory in unbalanced Chinese-English bilinguals
指導教授 : 吳嫻
系所名稱 : 認知與神經科學研究所
論文頁數 : 117
中文關鍵字 : 言語短期記憶、探針序列回憶派典、字形相似度、雙語、fMRI
英文關鍵字 : verbal short-term memory、the probed serial recall paradigm
中文摘要 :
過去研究拼音語言讀者的文獻顯示,言語的訊息主要以語音表徵維持在短期記憶內,而非視覺表徵。相對的,中文讀者的短期記憶則同時展現來自語音和字形表徵的貢獻。為了探討雙語使用者的短期記憶是受其母語特性或受刺激材料影響,此研究分別檢視英文母語者和中英雙語使用者的英文字音、字形相似效果。另外,此研究也透過功能磁振造影,比較英文短期記憶中語音和視覺表徵相關的神經機制,在此兩種語言使用者之間的異同。
此研究包含兩個實驗。實驗一由兩個使用探針序列回憶作業 (probed serial recall task) 的行為實驗組成。行為實驗結果顯示,英文母語者的英文短期記憶只受到字音相似度干擾、而不被字形相似度影響;另一方面,中英雙語使用者的英文短期記憶則同時受到字音和字形相似度影響。另外,雙語使用者的英文能力似乎也會調節字形相似效果的強度。實驗二是功能核磁共振腦造影 (fMRI) 實驗,使用類似前一實驗的探針序列再認派典 (probed serial recognition paradigm)。腦造影結果大致於言語短期記憶作業時呈現左側化的額顳頂葉活化網絡,且在字音相似效果下呈現左側化的額頂葉活化網絡。另一方面,視覺相似效果的活化則在英文讀者和中英雙語使用者分別呈現右側及雙側額頂葉網絡。大致上,與字音和字形相似效果相關的腦部活化在英文母語者較側化,而在中英雙語使用者顯得較平均雙側化。
本研究結果指出,雙語使用者的言語短期記憶表徵,同時受到其母語的特性及第二語言的能力影響,並且行為觀察到的字形相似效果可能與雙側化的額頂葉活化有關。
英文摘要 :
Previous findings from readers of alphabetic languages demonstrate that verbal information in short-term memory (STM) is mainly retained by phonological but not visual representation. In contrast, our previous findings from Chinese readers demonstrate the contribution from both phonological and orthographic representation. To investigate whether bilinguals’ STM is delineated by characteristics of the native language or by the to-be-remembered materials, the effects of phonological and visual similarity of English words in native English speakers and in Chinese-English bilinguals were examined. The neural substrates underlying the phonological and visual representations of English words during STM tasks are also compared between native English speakers and Chinese-English bilinguals.
Two experiments were conducted in this study. Experiment 1 consisted of two behavioral experiments using a probed serial recall task. The results of the behavioral experiments showed that English speakers’ STM was only hindered by phonological but not visual similarity of English materials, while the STM of Chinese-English bilinguals was affected by both phonological and visual similarity. Furthermore, bilinguals’ proficiency in English seemed to modulate the effect of visual similarity. Experiment 2 was an fMRI experiment employing a similar task with the probed serial recognition paradigm. The neuroimaging results generally showed a left lateralized fronto-temporo-parietal network of verbal STM and a left lateralized fronto-parietal network of the phonological similarity effect (PSE). On the other hand, the results showed a right lateralized and bilateralized fronto-parietal network of the visual similarity effect (VSE) in native English readers and Chinese-English bilinguals, respectively. In general, the activations associated with the PSE and the VSE were more lateralized in the native English participants while being more bilateralized in the Chinese-English participants.
The present findings suggest that the representation underlying bilingual verbal STM is jointly determined by features of the first language and proficiency of the second language, and that the behaviorally observable VSE might be associated with the bilateralized fronto-parietal activations.
 
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