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认知与发展心理学论坛第六次讲座
作者: 认知与发展心理学研究室 ║ 日期: 2011/12/01 

报告题目:The role of accentuation in conveying semantic meaning and in modulating attention allocation
     during spoken language comprehension: Evidences coming from ERPs and brain oscillations
报告人:李晓庆
报告时间:12月6日 13:30-14:30
报告地点:东楼D104教室
报告摘要
Spoken language comprehension requires a timely coordination of a number of different information types: semantic, syntax, prosody. An important difference with written language is that spoken language carries prosodic information. The present study aimed to examine the mechanism by which one aspect of prosody, accentuation, influences spoken language comprehension. Mini Chinese discourses were used as stimuli, with a question or un-question context sentence preceding the target sentence. The critical words in the target sentences were highly expected new information or low expected new information, which were accented (consistent) or de-accented (inconsistent). The results revealed that, in both question and un-question context, for highly expected new information, inconsistent accentuation (de-accented) elicited a larger N400 than consistent accentuation (accented); further time-frequency analysis found that theta power (4-6 Hz) increased while processing inconsistent accentuation, indicating the difficulties in lexico-semantic retrieval while accentuation was inconsistent. However, for the low expected new information, N400 amplitude was larger for consistent accentuation (accented) than for inconsistent accentuation (de-accented); meanwhile, upper alpha power (11-14 Hz) decrease was found for consistent accentuation, suggesting more attentional resources allocated to the accented information. The results demonstrated that accentuation influences spoken language comprehension both by conveying semantic meaning and by modulating attention allocation. More importantly, the effect of accentuation on spoken language comprehension and its neural underpinning changed with the information stored in the long-term memory.
In another ERP experiment, we further investigated how, or even if, the attention captured by accentuation influences the depth of or the time course of the subsequent semantic processing; and how the degree of accentuation influences the role of accentuation. Isolated Chinese spoken sentences were used as stimuli. The critical word in the carrier sentence was either semantically congruent or incongruent to the preceding sentence context. Meanwhile, the critical word was de-accented (DeAccent), generally accented (Accent), or greatly accented (GreatAccent). Results showed that, relative to semantically congruent words, the semantically incongruent word elicited a parietal-occipital N400 effect in the Accent condition and a broadly distributed N400 effect in the GreatAccent condition; however, the N400 effect was reduced and didn’t reach significance in the DeAccent condition. Further onset analysis found that the N400 effect in the GreatAccent condition started around 50 ms earlier than that in the Accent conditions. In addition, in the GreatAccent condition, the incongruent words also elicited an early negative effect in the window latency of 110-190 ms after the acoustic onset of the critical word. The results indicated that, during on-line speech processing, accentuation can rapidly modulate temporally selective attention and consequently influence the depth or the speed of subsequent semantic processing; the effect of accentuation on attention allocation and semantic processing can change with the degree of accentuation gradually.

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