以個體差異觀點探討句法、語意及論旨角色所引發之晚期正波

Individual Variation in the Late Positive Complex to Syntactic, Semantic, and Thematic Anomalies

莊勻(Yun Ingrid Chuang)

指導教授 ： 李佳霖

國立臺灣大學/文學院/語言學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104401

摘要

近來研究發現論旨角色顛置之語意不通順的句子引發「語意P600」效果。因為皆明顯分佈於頭皮中後區並皆為晚期正波，一些理論支持「語意P600」和被語法錯誤或語法處理困難引發之「語法P600」反映類似之功能與神經基礎。這個看法頗具爭議，因為另有理論認為「語意P600」與語意不通順引發之亦分佈於頭皮中後區的晚期正波「LPC」效果功能相當。有些研究更認為這三種晚期正波反映了類似的處理機制。
為了討論這個爭議，我們採取比較個體差異的進路，關注擁有「家族左利史」與否（指個體有無慣用左手之生理親屬）對語言處理的影響。我們假設若某變因會調節一事件相關電位效果之引發，那麼此變因也將以類似方式調節另一反映類似歷程之事件相關電位效果的引發。過去研究指出家族左利史對語法P600和LPC之引發具不同的影響：與沒有家族左利史之受試者相比，有家族左利史之個體傾向不對語意不通順之刺激引發LPC；而不管有無家族左利史，受試者皆會引發語法P600，但是有家族左利史的人會引發額外的N400效果。
根據這些家族左利史影響語言處理的發現，本研究旨在檢驗家族左利史是否以及如何影響語意P600效果之引發，以釐清語意P600效果反映之功能和其本質。本研究招募了32位無家族左利史和32位具家族左利史之年輕、右利並且臺灣華語具母語程度的受試者。受試者們閱讀了語法、語意、論旨角色通順和不通順的句子（句子拆為字詞呈現於螢幕中央），並按鍵回答閱讀之句子通順與否。 和預期一致，不具家族左利史之受試者對於語法、語意、論旨角色的操弄分別引發了語法P600、LPC以及語意P600效果。本研究亦複製了過去研究中家族左利史影響語言處理的發現：具家族左利史之受試者產生了語法P600，但對於語意異常並沒有引發LPC效果。另外，家族左利史影響論旨角色處理的方向和其影響語法處理之方向顯著不同，但是和其影響語意處理的方向沒有顯著差異。本研究之結果可為家族左利史會影響語法P600和LPC效果之引發背書；並且，本研究不認同宣稱語法P600和語意P600為同一事件相關電位效果之假說，亦不支持認為此三種晚期正波皆反映類似神經與認知功能之假設。

關鍵字

家族左利史 ； 個體差異 ； 事件相關電位 ； 語法P600 ； 語意P600 ； 晚期正波

並列摘要

Sentences involving semantic reversal anomalies have recently been shown to elicit the “semantic P600” effects. With similar central-parietal scalp distributions and late time courses, the “semantic P600” is assumed by some theories to reflect similar functional and neural underpinnings as a more well-established effect--“syntactic P600”, that is elicited by syntactic errors or syntactic processing difficulties. This view, however, is not without controversy, as an alternative hypothesis holds that semantic P600 may be functionally equivalent to the late positive complex (LPC)—another late central parietal positive deflection that is usually seen to semantic anomalies. Furthermore, some studies postulate that all three late positivities reflect similar processing mechanisms.
To shed light on this debate, we turn to an individual difference, familial sinistrality (FS, whether or not one has left-handed biological relatives), assuming that variables known to affect an ERP effect should similarly modulate other ERP effects that share similar cognitive-neural underpinnings. Past findings demonstrated non-identical modulatory influences of FS on LPCs and syntactic P600s. Compared to FS- individuals, FS+ individuals are less likely to elicit LPCs to semantic anomalies. FS+ individuals elicit similar syntactic P600s to syntactic anomalies like FS- individuals do but are more likely to show additional N400 responses. In light of these findings, the present study set out to examine whether and how FS might modulate semantic P600s to help delineate the functional correlates of the semantic P600. 32 FS- and 32 FS+ young right-handed Taiwan Mandarin speakers were recruited to read sentences with or without sentence-final semantic, syntactic, or thematic anomalies. Participants read these sentences one word at a time from the center of a computer screen and judged if the sentences were plausible by pressing hand-held buttons.
As expected, FS- participants showed significant positive responses to all three types of anomalies. Replicating prior findings of FS influences, FS+ participants showed significant syntactic P600s to syntactic anomalies, but no LPCs to semantic errors. In addition, the pattern of FS influences in thematic anomalies is significantly different from that of syntactic incongruence and has no apparent distinction from that of semantic inconsistency. These results endorse differential influences of FS on syntactic P600 and LPC. Furthermore, our data do not support the idea that syntactic P600 and the semantic P600 are the same effects, as well as that all late positive components reflect similar functional mechanisms.

並列關鍵字

familial sinistrality ； individual difference ； ERPs ； syntactic P600 ； semantic P600 ； LPC

參考文獻

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