重读对口语理解中时间选择性注意分配的影响

采用事件相关电位（ERP）技术来研究重读如何影响口语加工中早期的选择性注意分配。并进一步研究重读的这种注意调控作用是否受声调的影响。实验以单个句子为实验材料，结果发现重读比不重读条件下的关键词更早的引起一个早期负波（N1），并且引起更大的N400。在两个时间窗口重读的效应都不受声调的调控。这些结果表明，在自然的口语理解过程中，重读能够快速的调控早期选择性注意的分配，并影响接下来的语义加工的深度。

How Accentuation Influences the Allocation of Temporally Selective Attention during On-line Spoken Language Comprehension

Previous studies have found that accentuation plays a very important role in spoken language comprehension. However, the specific mechanisms of accentuation affecting spoken language processing remain matters of debate. One account is that accentuation is related to the focus distribution of the sentence, the other is that accentuation influences speech processing by modulating the allocation of selective attention. The purpose of the current study is to explore (1) how accentuation influences the allocation of temporally selective attention during on-line spoken language comprehension. In Chinese, different lexical tones’ pitch patterns are different when being accented, so we want to explore (2) how the effect of accentuation on attention allocation changes with lexical tones.To study temporally selective attention, the EEG technique and attention probe paradigm were used in the present study. A linguistic attention probe ‘ba’ was presented concurrently with the critical word in the sentence. The materials used in the present study were isolated Chinese spoken sentences, i.e. sentences presented without explicitly provided discourse-level contextual information. All the critical words were single Chinese words. The stimuli were presented through E-prime 1.1. The critical word in the carrier sentence was either accented (Accent) or de-accented (DeAccent). Meanwhile, its lexical tone was either tone three (Tone Three) or not (not Tone Three)（tone one or tone four）. Thirdly, the critical word in every sentence was added with a linguistic attention probe (a pure tone “ba” lasting 50ms) or not. Subjects were instructed to listen to the sentences carefully but ignore the probe. The brain electrical activity was recorded from 64 electrodes mounted on the participants’ heads with Neuroscan 4.3 software (NeuroScan, Herndon, VA, USA).Firstly, to estimate whether N1 effect was elicited by the attention probe, we analyzed the eight original ERP waveforms and found that, relative to the critical words without probe, the critical words with probe elicited a larger N1 effect. Secondly, to examine how accentuation and lexical tone modulated the N1 effect, difference waveforms (the condition with probe subtracts the condition without probe) in the four experimental conditions (Accent-Tone Three, Accent-not Tone Three, DeAccent-Tone Three, DeAccent-not Tone Three). The results showed that, relative to the DeAccent condition, the Accent condition elicited an earlier N1 effect [F（1,18）=7.75，P<0.001], and the N1 effect of accentuation was not changed with lexical tones. Furthermore, to examine how accentuation and lexical tone influenced the later stage of semantic processing, the original ERP waveforms elicited by the critical word that was not added with an attention probe was analyzed. The results showed that, in the time window of N400, accented critical words elicited a larger N400 than de-accented critical words [F(1，18)=27.84，P<0.001]. No significant interaction between accentuation and lexical tone was found. These results indicated that, during on-line speech processing, accentuation can modulate temporally selective attention （the information that was accented can attract more attention） and consequently influence the depth of subsequent semantic processing. The effect of accentuation on attention allocation was not affected by lexical tones. Combining the results of time window of N1 and N400 we speculate that accentuation can influence speech processing by modulating listeners’ selective attention.