英文單字辨識的語音促發歷程：功能性核磁共振造影的研究

Phonological Priming in Visual Word Recognition for English Words: An Event-Related Functional MRI Study

此篇研究採用功能性核磁共振（fMRI）來探討閱讀英文單字時，字形、字音、與字義如何交互影響閱讀的歷程。實驗的刺激嘗試是英文的字對，以促發的程序來安排，受試者閱讀連續出現的兩個刺激嘗試，並要判斷第二個刺激嘗試是否為一個合法的英文字。當兩個刺激嘗試為同音字對時，實驗者觀察第一個刺激嘗試如何去影響受試者對第二個刺激嘗試的判斷，並檢視其對應的神經機制。此外，第二個刺激嘗試並根據字的形音對應關係，分為規則字與不規則字，藉此探討在促發的實驗設計下，字的規則性如何去影響受試者對第二個刺激嘗試的判斷。三個主要的實驗的結果如下：第一，當英文字對包含不規則字時，由於字形與字音的轉換困難導致字義的涉入，在左腦半球的顳葉中區（BA 21）產生大腦神經活動增加的現象。第二，當英文字對包含規則字時，由於字形與字音的轉換容易，在左腦半球的頂葉下區（BA 40）產生大腦神經活動減少的現象。第三，同音字對與控制組字對相比較，因為對字形的檢查處理以判斷字的合法性，在左腦半球的視覺聯結區（BA 37）產生大腦神經活動增加的現象；同樣地，非合法的英文字對與合法的英文字對比較，在相同的區域產生大腦神經活動增加的現象。這些實驗結果建議，在行為資料中所產生的同音促發效果，是由數種的處理歷程所構成，並且反映在增加與減少的神經活動上。

Functional magnetic resonance imaging (fMRI) was used to explore the nature of the mappings between orthography, phonology, and semantics in reading English words. Stimulus pairs were arranged in a priming paradigm with lexical decision to understand the neural correlates of phonological processes. Homophonic targets varied in the regularity of the mapping from spelling to sound (e.g., feet-feat, bare-bear). There were three main findings. First, the results revealed that the left middle temporal gyrus (BA 21) showed increased neural activity for phonologically primed irregular pairs consistent with increased semantic involvement in making lexical decisions when the mapping between orthography and phonology is made difficult. Second, the left supramarginal gyrus (BA 40) was associated with reduced neural activity for phonologically-identical pairs with regular spelling to sound correspondences, when the mapping between orthography and phonology is made easy. Third, the visual association cortex including the left fusiform gyrus (BA 37) showed more activation in the homophone pairs compared to the unrelated pairs and more activation for pseudoword targets compared to word targets, suggesting that this region may have been involved in a spelling check on lexical decisions. These three findings show how phonological priming effects on behaviour can result from a complex interaction of several processing phases involving both increases and decreases of activity.