以事件相關電位研究情緒預測在句子處理中的影響

文獻顯示當實驗材料為圖形刺激時，大腦在能預測情緒事件時呈現較活化的反應。然而，以語言為媒介所建構的情緒預測是否能引發相同的效果仍不清楚。在本篇研究中，我們提出量化的方式來計算以語言為情境所產生的情緒預測—藉由把某些字詞作為某一特定句子結尾的克漏字機率(cloze probability)乘以每一字詞的正負向性，加總後得到此一句子在情緒預測上的數值。我們採用強烈或微弱情緒預測的語境，以情緒詞或中性詞作為結尾，產生通順或不通順的句子。我們讓27位受試者以單字詞呈現在電腦螢幕上的方式閱讀這些句子，同時記錄大腦對句子結尾字詞的事件相關電位反應。與先前大腦事件相關電位研究上典型的通順效果(plausibility effect)相同，不通順的字詞比通順字詞引發較大的N400及晚期正波(late positivity)反應，顯示在處理不通順的句子時所產生的整合困難及後續再分析的效果。此外，與先前研究一致，情緒詞比中性詞引發較大的晚期正波反應，且不受句子通順程度及情緒預測程度的影響，顯示出情緒詞由於動機上的重要性引發較多的注意力以及對眼前情勢進行更深入的評估。而針對本篇研究的主要重點—以語言為媒介所建構的情緒預測對後續字詞的影響，我們的結果顯示語境的情緒預測程度的確影響了情緒詞與中性詞在N400及晚期正波的反應：不論後續字詞是情緒詞或中性詞，強烈情緒預測的語境皆引發較小的N400與較大的晚期正波，再次指出對於情緒的預期能透過動機機制(motivation system)引發較多的注意力及較大的腦內活動，進一步對之後的情緒事件做較好的準備。更重要的是，我們發現情緒詞在強烈和微弱情緒預測的通順句子下對於情緒詞所引發的腦波差異能被受試者的同理心分數所預測—分數較高的受試者引發的腦波差異較小。總體而言，本篇研究擴展了我們對情緒處理的認識: 藉由語言塑造出的情緒預測也能調節對即將面臨的事件的注意力以及動機機制，且此項能力與察覺並理解他人情緒的能力有正相關。

關鍵字

情緒預測；語言；事件相關電位；同理心；晚期正波

並列摘要

Previous research using pictorial stimuli has shown that emotional expectations enhance brain activations to emotional events. However, whether emotional expectations built up through linguistic means similarly modulate brain responses to subsequent emotional events is still unknown. Here we propose a metric for quantifying emotional expectations in linguistic context by summing over valence values of possible endings of a sentence weighted by their cloze probability in that particular context. Sentential contexts with strong or weak valence constraints were then completed with plausible or implausible emotional or neutral words. Event-related brain potentials were recorded while 27 participants read these sentences word by word from a computer screen and responses time-locked to the sentence final words were analyzed. Replicating the classical ERP plausibility effects, implausible critical words elicited larger responses on the N400 and the late positivity components (LPC) than did plausible words, reflecting the integration difficulty and subsequent reanalysis in the implausible sentences. In addition, consistent with past findings, emotional words also elicited larger LPCs than did neutral words, regardless of sentence plausibility and valence constraints, reflecting additional attention resources and deeper assessment of the immediate situation due to motivational significance. Of central interest to this study, sentential valence constraints modulate the processing of the upcoming word in that responses to both emotional and neutral words in both the N400 and LPC time windows were found to be more positive to critical words in strong versus weak valence constraint sentences, again indicating the engagement of motivation system that allocates attention resource and interior tension as a preparation for the subsequent emotional events. More importantly, our results showed that response differences to plausible emotion words in strong versus weak valence constraint sentences can be predicted by individuals’ empathy scores, with higher scores associated with smaller response differences. Over all, the current findings extend our understandings about emotion processing by demonstrating that emotional expectations established based on linguistic means also enhance responses from the attention and motivation systems to the imminent events, and that this ability positively correlates with individual’s ability to recognize and understand others’ emotions through non-verbal cues.

並列關鍵字

emotional expectation ； language ； event-related potential ； empathy ； late positivity component

參考文獻

Bayer, M., Sommer, W., & Schacht, A. (2010). Reading emotional words within sentences: The impact of arousal and valence on event-related potentials. International Journal of Psychophysiology, 78(3), 299–307. http://doi.org/10.1016/j.ijpsycho.2010.09.004

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以事件相關電位研究情緒預測在句子處理中的影響

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