| 其他摘要 | When we communicate vocally, it is often not just what we say - but how we say it - that matters. The latter, which is termed emotional prosody or vocal emotion, is the way to communicate emotion vocally that beyond verbal content by modulating acoustic cues such as pitch, intensity, rhythm, and vocal qualities. The neuro-cognitive mechanisam of vocal emotion processing has got increasing interests as there has been abundance of studies exploring the time course and brain areas responsible for vocal emotion perception and two quite sophiscated models recarding emotional prosody processing has been put forward. However, almost all the previous researches ignored the modulation of its own feature and task demands during emotional prosody processing. Therefore, the present thesis investigated the impact of stimulus features and task demands in the perception of vocal emotion from three aspects by taking the advantage of the high time resolution of ERP technique. The main findings are listed as following: 1. The brain detects the expectancy violation rapidly, indexed as an early negativity （N2） elicited by emotional prosody deviation, whose peak latency varied with deviation pattern. Moreover, a late positivity (P3) was specifically induced by the deviation and was modulated by both deviation pattern and task-relevance, reflecting a process of raising vigilance and and then integrating with the context for comprehension. The expectancy violation effects cannot be simply attributed to the change in non-emotional acoustic properties and the emotionality plays a role of speeding up the perception and enhancing vigilance.The vocal emotion processing follows the general rule of auditory perception, that is, it is based on predictive representation of temporal regularities, which are continuously generating expectations of the future behavior of sound sources. 2. Sound intensity, the frequently ignored acoustic cue, also plays an important role in vocal emotion communication, that is, athough it cannot categorically affect emotionality conveyed in emotional prosodies, it contributes to emotional significance quantitatively, implying that it should be cautious to take sound intensity as a control parameter in vocal emotion studies. 3. The possibility to be rated as happy increased gradedly as the morphing level increases, while the amplitude and peak latency of P200 decreased gradedly, suggesting the neutral and emotional vocal stimuli might be processed continuously in the early stage. However, the amplitude and latency of P300 changed categorically when the morphing level changes, implying a categorical processing of vocal emotion in explicit and high level cognitive processing. Moreover, these effects cannot be simply attributed the acoustic changes. 4. Neutral and happy vocal stimuli can be distinguished within 200 ms under implicit and explicit task demands and then differentiatd at 400ms under explicit task condition. The temporal lobe and frontal lode were significantly activated during the two stages respectively. These results suggest that the brain can differentiate neutral and emotional vocal stimuli when performing implicit and explicit task, but only explicit processing can apply the emotional significance to higher cognitive processing in later time point. Therefore, the current study suggested that it should take the genereal role of auditory processing into consideration in the study of vocal emotion perception. Moreover, the context, single acoustic cue and emotion intensity have salient impact on such process. In addition, taking the advantage high time resolution of EEG technique, the current data provide more evidence for the hierarchy model of emotional prosody. |
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