本文透過操弄雙字詞詞首的語意(sense)多寡和左右視野，試圖探討中文雙字詞的語意表徵和左右大腦對於多意詞(polysemy)的處理機制。實驗一顯示的左右腦結果和Pylkkänen等人在2006年的MEG研究相似，也就是左腦的多意詞促進效果，支持多意詞單一表徵的型態；然而，右腦卻呈現多意詞抑制的效果。這樣的現象產生兩者可能解釋：(1) 右腦還是屬於單一語意表徵，但由於右半腦處理語意的特性，導致和左腦得到不同的結果；(2)右腦的結果是來自於右腦屬於語意多重表徵(separate entries)的因素。為了要釐清這些說法，實驗二進一步的改變作業深度，讓受試者做詞類判斷作業，企圖讓受試者進行比較深層的語意處理。實驗二結果顯示，在改變作業深度之後，我們的確得到右腦語意促進效果，所以證明右腦的語意屬於單一表徵，在比較深層作業處理階段，因為左右腦處理語意的特性，使得右腦有機會呈現實驗預期的結果。另外，在動詞、名詞事後分析的結果中，我們也發現動詞、名詞的語意效果在大腦有不同的分布區位。名詞的語意效果分布在大腦中間偏後的位置；動詞則是主要分布在大腦前額一帶 總結以上發現，本研究的發現支持過去學者所提出的多意詞單一表徵的說法；第二、本研究對左右半腦處理語意特性，也符合過去的假設，也就是左腦擅長主要、細微的辨識，右腦則擅長維持次要、普遍語意。第三、本研究額外的發現是，動詞、名詞的語意效果在大腦有不同的分布，意味著不同的詞類在大腦可能有不同的表徵。 / Acknowledgements …………………………………………………………iv Tables…………….……………………………………………………………ix Figures …………………………………………………………………………x Chinese Abstract …………………………………………………………xii English Abstract ………………………………………………………xiii CHAPTER 1. INTRODUCTION ……………………………………………………..……1 1.1 What are senses? Homonymy vs. Polysemy …………………….1 1.2 English words vs. Chinese compounds ………………………….3 1.3 Hemispheric processing of semantic ambiguity ……………4 2. REVIEW OF RELATED PSYCHOLINGUISTIC RESEARCH ………………6 2.1 Neighborhood size effect in English …………………………6 2.2 Neighborhood frequency effect …………………………….……9 2.3 Event-related potentials (ERPs) vs. neighborhood size effect....11 2.3.1 Event-related potentials ………………………………….11 2.3.2 The advantages of electrophysiological techniques …12 2.3.3 Language-related ERP components ……………………….…12 2.3.4 The neighborhood size effect and. ERPs ……………..14 2.4 Neighborhood size effect in Chinese ……………………….16 2.5 Lexical ambiguity in English—homonymy vs. polysemy……… 22 2.5.1 Mixed results of ambiguity effects ………………………23 2.5.2 Polysemy—separate entries or single entry? …………25 2.5.3Some evidence for single entry hypothesis of senses…27 2.6 Lexical ambiguity in Chinese …………………….……………26 2.7 Hemispheric asymmetry in lexicon processing ……………33 3. EXPERIMENT 1 ………………………………………………………………38 3.1 Experiment 1... ..……………………………………….….....39 3.1.1 Participants …………………………………………………………39 3.1.2 Materials ……………………………………………………………39 3.1.3 Procedure ……………………………………………………………40 3.2 EEG recording parameters …………………………………………41 3.3 EEG data analysis procedure …………………………….....42 3.4 Results ……………………………………………………………………43 3.4.1 Behavioral data of sense effect ……………………………43 3.4.2 Behavioral data of lexicality effect ……………………44 3.4.3 Event-related potentials ………………………………….…45 N170 (150- 180 ms) …………………………………………………46 Frontal P200 (220-260 ms) …………………………………….……47 N400 …………………………………………………………………48 3.5 Discussion ……………………………………………………………51 4. EXPERIMENT 2 ……………………………………………………………57 4.1 Experiment 2 …………………………………………………………58 4.1.1 Participants ………………………………………………………58 4.1.2 Materials …………………………………………………………58 4.1.3 Procedure ……………………………………………………………59 4.2 Results …………………………………………………………………60 4.2.1 Behavioral data ……………………………………………………60 4.2.2 ERP data ……………………………………………………………61 N170 (150-180 ms) ………………………………………………....62 Frontal P200 (220-260 ms) …………………………………………63 N400 (350-500 ms) …………………………………………………63 4.3 Discussion …………………………………………………………………….65 Nouns and verbs ………………………………………………………67 4.4 Re-analyses …………………………………………………………69 4.4.1 Behavioral data ……………………………………………………69 4.4.2 ERP data ……………………………………………………………....71 Nouns …………………………………………………………………71 Verbs …………………………………………………………………74 4.5 Discussion 2 ………………………………………………………77 5. GENERAL DISCUSSION AND CONCLUSIONS ………………………81 5.1 Separate entries or single entry? …………………………81 5.2 Hemispheric processing of polysemy in different depth of tasks ………....82 5.3 Nouns and verbs ………………………………………………………84 5.4 Conclusions …………………………………………………………….85 References ……………………………………………….……………………86 Appendixes ………………………………………………………….…….94 / The current study used the manipulation of visual field and the number of senses of the first character in Chinese disyllabic compounds to investigate the representation of senses and the hemispheric processing of semantic polysemy. The ERP results in experiment 1 revealed crossover patterns in the LH and RH, which resembled the MEG data in Pylkkänen et al.’s study (2006). The sense facilitation in the LH was in favor of the assumption of single entry representation for senses. However, the inhibition in the RH yielded two possible interpretations: (1) the nature of hemispheric processing in dealing with semantic ambiguity; (2) the semantic activation from the separate-entry representation for senses. To clarify these possibilities, the depth of the task was changed. Experiment 2 was designed to push subjects to a deeper level of lexical processing through the word class judgment task. The results revealed the sense facilitation effect in the RH and suggested that in a deeper level, the RH had more possibility to observe the sense facilitation due to different efficiency of cerebral hemispheres in dealing with ambiguity. By chance, planned comparisons of the sense effect in different word classes suggested different distributions of the sense effects for nouns and verbs. For nouns, the sense effects were located in central-to-parietal areas while for verbs, the sense effects mainly were from the frontal area. In sum, the current study was in support of the account of single entry representation for senses, which was consistent with previous findings proposed by Beretta et al. (2005), Pylkkänen et al. (2006), and Rodd et al. (2002). Second, the research demonstrated that cerebral hemispheres played a role in semantic activation in a complementary way in which the LH was engaged in fine and focused semantic coding while the RH was more sophisticated in coarse coding and maintaining alternate meanings (e. g. Beeman & Chiarello, 1998; Burgess and Simpson, 1988). When the depth of tasks was changed, the RH advantage for the processing of semantically related senses was observed. Third, different distributions of the sense effects for nouns and verbs implied the distinct representations for different parts of speech in the brain.