從腦傷病人之研究簡介語文材料中的單字處理歷程

Single Word Processing: Insights from Research on Brain-damaged Patients

認知神經科學研究的主要目標，在於闡釋人類大腦與行為之間的關係。在數種使用於此一領域的先進技術中，對於腦傷病人的研究具有長久的歷史，同時有其獨特的貢獻。某些腦傷病人的選擇性認知能力損傷，說明了和該作業相關的認知成分在功能上的獨立；兩個功能的雙重分離，更顯示其組成成分可能在行為功能和生理解剖上有不同的機制，以致其中一者單獨被腦傷所影響、而另一者則保存完整。在此文獻回顧中，首先簡介主要根據腦傷病人的失常行為所建構出的Wernicke-Lichtheim理論，並簡介對此傳統模式的評論和修正。本文接著將扼要地彙整神經心理學研究中，關於單一詞彙理解和產生歷程的實驗結果，同時對於部分支持詞彙具有獨立語法及語意表徵的證據，也作一簡要的討論。從此認知神經心理學的文獻回顧，我們不難發現：自Wernicke-Lichtheim理論提出之後，認知心理學家對於單一詞彙處理的各項功能以及所牽涉到的各種表徵，已有相當程度的瞭解。特別是在過去的二十幾年中，我們對於單一詞彙在口語及文字處理中所經過的歷程，也累積了相當豐富的知識。腦傷病人之正常和失常的行為表現，為許多在文獻中備受爭議的問題，點出了重要的研究方向，也為不同的假說提供了重要的佐證。此一領域應奠基於既有的知識，增加對語句層次之語言處理歷程的探討，以助完整之語言處理理論的發展。

The relationship between the brain and behaviors has been the focus of the research in cognitive neuroscience. In addition to linking different neural substrates to different cognitive abilities, studies in this field have provided valuable information on the mechanisms underlying human cognition. Compared with other advanced techniques employed in cognitive neuroscience, studies on brain-damaged patients have a long history and unique contribution to the field. Specifically, the selective disruption of some task performance signifies the functional independence of a cognitive component subserving that task. The double dissociation between two functions further suggests the dissociation, possibly both functionally and anatomically, of two components. In the current overview, I first introduced the Wernicke-Lichtheim model, which is mainly constructed from brain-damaged patients’ behavioral impairments. I also reviewed the criticisms and modifications to this traditional view. Next, the neuropsychological findings regarding the processes involved in single word comprehension and production were summarized. Evidence for separate lexical, syntactic, and semantic representations of a word was briefly discussed. Among lexical representations, further segregation between input and output phonological and orthographic representations was demonstrated by case reports on single patient’s selective deficits. The organization of semantic and grammatical representations was also proposed to account for patients’ performance. From this overview of cognitive neuropsychological findings, we can conclude that our understanding of the functional organization of single word processing has progressed considerably since the Wernicke-Lichtheim model was proposed. In particular, considerable knowledge has accumulated concerning the organization of the systems involved in single word processing for both speech and writing during the past two decades. The data-collected have had important implications for various issues that have been greatly debated in the normal literature. More work is needed to elucidate the linguistic processing/representations at the sentence level and to contribute to the development of theories of language processing.