汉语句子和语篇韵律层级边界的认知加工及其ERP效应

The aim of the present study was to explore whether the CPS (Closure Positive Shift) which reflected prosodic processing will be elicited when listeners perceived different hierarchical prosodic boundaries in Chinese sentence and discourse (Quatrain). In addiction, the similarity and difference in amplitude, onset latency and scalp distribution between these CPS were investigated. The nature of the CPS and its relationship to acoustic parameters was also explored systematically. The main results and conclusions of the present study were: (1) Phonological phrase boundaries and intonational phrase boundaries in Chinese sentences both elicited the CPS; however, phonological word boundaries can't evoke it. The CPS induced by phonological phrase boundaries was earlier than the one related to intonational phrase boundaries in onset latency, and the amplitude was also somewhat lower. When the pauses in the vicinity of these two boundaries were removed, the onset latency difference disappeared while amplitude in the new conditions was also lower. This indicates that whenever listeners segment sentence into phrases, the CPS will be elicited. Besides, pause was not the decisive factor to elicit the CPS, but can modify its onset latency and amplitude effectively. (2) The different hierarchical prosodic boundaries in seven character quatrain including phonological phrase boundaries, intonational phrase boundaries and sentence pair boundaries elicited the CPS respectively. Furthermore, just like in the sentence level, onset latency of the CPS induced by the prosodic boundaries in the discourse was also influenced by the length of pause: the shorter the pause was, the earlier the onset latency. For the comparison between the CPS evoked by the same and different hierarchical prosodic boundaries, its amplitude was influenced by the extent to which prosodic representations were activated. Thus, the condition of the CPS elicitation was extended to the prosodic bounaries in discourse, and further indicated that it was influenced by acoustic parameters. (3) No matter what task the participants completed, just like word detection or rythem matching task, the CPS will be evoked. However, its amplitude was larger in the anterior region, when listeners completed the word detection task which needed more attention and higher load of working memory. The present result indicated that the elicitation of the CPS was not influenced by the task the participants completed, but different task influence its scalp distribution. (4) The final syllable of the sentence and quatrain can't elicit the CPS, but a P300-like positive component. Although the scalp distribution was similar to the CPS, it was much higher in amplitude. The present result suggested that only the prosodic boundaries reflecting not only the closure of the former prosodic unit but also integrating the later one will elicit the CPS.

本研究采用ERP技术，利用汉语中存在大量同声异形字的特点以及特有的语篇绝句考察听者在加工汉语句子和语篇不同层级韵律边界时，是否能够诱发反映韵律边界加工的特定性ERP成分CPS (Closure Positive Shift), 并考察不同边界诱发脑电效应在波幅，开始潜伏期和头皮分布等方面的异同。系统探讨了CPS的诱发本质及其它与声学线索之间的关系。 本研究得到的结果和结论主要有： （1）在句子水平上的研究发现，语调短语边界和韵律短语边界都能诱发CPS，但是韵律词边界不能诱发这个成分。韵律短语边界诱发的CPS在开始潜伏期上早于语调短语边界诱发的CPS，波幅也略低。然而，将两种边界处的无声段切掉以后，两者的开始潜伏期差异消失，波幅也有所降低。本研究表明，听者只要将句子切分成短语即可诱发这个成分；无声段虽然不是诱发CPS的决定性因素，但是可以影响它的开始潜伏期和波幅。 （2）七言绝句内部不同层级的韵律边界包括音系短语边界，语调短语边界和句对边界都能诱发CPS，并且各级韵律边界无声段越短，开始潜伏期越早。此外，对比同一层级和不同层级韵律边界诱发的CPS，一致表明其波幅受到韵律激活程度的影响。本研究将CPS的诱发条件扩展到了语篇水平上的韵律边界，并进一步说明CPS受到声学参数的影响。 （3）被试在加工七言绝句过程中，不论完成节奏匹配任务还是词汇探测任务都会诱发CPS。但是，受到词汇探测任务需要被试分配较多注意力和更大工作记忆负荷的影响，其波幅在前部较大。本研究由此表明CPS的诱发不受被试完成任务的影响，但是任务难度会影响其头皮分布。 （4）句子和绝句末尾不能诱发CPS，而是一个类P300的正波；在头皮分布上与句内边界诱发的CPS类似，但是波幅要显著高于它。从而表明，只有在句子或者语篇内部既包括对韵律单元中止又整合的边界才能诱发CPS。