閱讀中文時詞頻與位置對詞彙競爭歷程的影響初探

中文的書寫單位為字，詞之間沒有明顯的界線。讀者需從有詞界線曖昧性（ambiguity）的文句中認詞。本研究假設中文讀者認詞歷程的運作機制裡，高頻詞與位置在前方的詞具有辨認的優勢，且前詞的辨認優勢較高頻詞大。藉由認詞歷程形成的高頻詞與前詞辨認優勢，可幫助中文讀者迅速從有詞界線曖昧性的文句中認詞。實驗一探討加大詞間空格對讀者閱讀速率的影響。操弄文章的書寫方式。結果發現加大詞間空格的書寫方式反而減慢讀者的閱讀速度。顯示中文讀者不需明顯的詞界線，以自動化認詞歷程的運作機制即可迅速從文句中認詞。實驗二試圖了解高頻詞優勢和前詞優勢是否存在，及前詞是否較高頻詞有更大的辨認優勢。結果顯示受試者判斷爭字型字串裡劃有底線的目標字串是否為詞時，目標高頻詞的反應時間較目標低頻詞快，顯示高頻詞有辨認優勢。但非目標詞為高頻詞對反應時間卻沒有明顯影響。目標為後詞時反應時間較快，顯示後詞有被辨認的優勢。推測非目標高頻詞對反應時間沒有影響是因位置對詞彙競爭歷程的影響較詞頻大的緣故。實驗三探討以爭字型字串做為促發項時，目標項是爭字型字串的前詞或後詞，及其詞頻對促發效果的影響。結果發現目標詞的位置或頻率及非目標詞的頻率皆未影響促發效果。推測是因為詞頻與位置對詞彙競爭歷程的影響在促發項的呈現時間結束前已完成，所以才無法從促發效果的結果看到影響。此外，促發組與非促發組目標項的詞頻未有良好配對，使實驗敏感度受到影響。實驗四修改上述問題，反應時間結果顯示後詞在詞彙競爭歷程中贏得競爭的優勢大於高頻詞的優勢。促發效果的結果則同樣顯出後詞較具辨認優勢之趨勢。綜合各個實驗的結果可推論出，中文讀者自動化認詞歷程運作的結果，讀者會優先認出高頻詞及後詞。而透過先認出高頻詞及後詞，可幫助中文讀者迅速從有詞界線曖昧性的文句中認詞。

關鍵字

詞界線曖昧性；詞彙競爭歷程

並列摘要

In written Chinese, characters are spaced evenly. There are no physical word boundaries. During reading, readers must be able to identify words in a visual environment full of word identification ambiguities. How do Chinese readers accomplish such an apparently complex task so efficiently and effectively? This study assumed that when a reader fixates on the text, the characters within the perceptual span activate words containing them in the mental lexicon. The automatic lexical competition of activated words helps resolve the word identification ambiguities, much like the process of identifying words in speech. In this study, the effects of word frequency and position on the lexical competition process were examined. It was hypothesized that words with higher frequencies and those at the front parts of the ambiguous strings dominate the competition. Experiment 1 tried to find out whether obvious word boundaries in Chinese text increase reading speed or not. We manipulated different written units in Chinese text, then we measured subject’s reading speed. Experimental results indicated that the text with obvious word boundaries significantly decreased the reading speed. It appeared even word boundaries are unobvious in Chinese text, Chinese readers can still identify words from text by using the automatic word identification process. Experiment 2 manipulated word frequency and target’s position of ambiguous three-character strings to investigate the effect of word frequency and position on the lexical competition process. Subjects were asked to make a lexical decision on the first two or last two characters of ambiguous three-character strings, than we measured their reaction time. The results showed that the reaction time of words with higher frequencies and those consisting of the last two characters of the ambiguous string were faster. The results also indicated that the competitive domination of words at the back parts of ambiguous strings was greater than words with higher frequencies. In experiment 3, we used priming paradigm to investigate the effect of word frequency and position on the lexical competition process. The results showed that neither word frequency nor word position affected priming effects. This presumably is because the priming group and non-priming group didn't have a good enough word frequency matching, so the experimental sensitivity was affected. Experiment 4 modified the above problems, and the results showed the same results with experiment 2, specifically that the competitive domination of words at the back parts of ambiguous strings was greater than words with higher frequencies. In conclusion, the automatic lexical competition of activated words makes words with higher frequencies and those at the back parts of ambiguous strings dominate the competition, helping to resolve the word identification ambiguities.