【作者】 袁加锦；

【导师】 李红；

【作者基本信息】 西南大学 ， 发展与教育心理学， 2009， 博士

【摘要】 人类情绪活动不仅存在情绪类别和情绪极性(积极/消极)之分,也有情绪强度,即效价强度的差别。日常经验提示我们,不同强度的负性情绪状态对个体生存适应及认知活动的影响是不同的。本学位论文主要考察人类如何加工正,负情绪刺激的效价强度,以及效价强度变化条件下人类情绪感受性的个体特殊性。因此,采用适合情绪感受性研究的高生态效度双选择oddball范式(见第二章),本学位论文包括4个ERP研究。研究一通过两个oddball实验,考察人类对正,负情绪刺激效价强度的情绪感受性及初步探讨其神经基础。研究二考察不同效价强度的负性情绪对视觉新异性加工的影响及其时间特征。研究三通过两个层次的实验,考察效价强度变化条件下,男女两群体对情绪图片的情绪感受性差异,以此探讨负性情绪识别的女性优势,以及情绪障碍发生率男女差异的认知与神经机制。研究四通过两个实验考查,在效价强度变化条件下,外倾性人格特质如何影响个体对正,负刺激的情绪感受性,以此探讨外倾个体的情绪感受性特点以及外倾性与主观幸福感的关系。实验以正常大学生为被试,所用刺激材料来自国际情绪图片系统(International Affective Picture system, IAPS,Lang et al., 2001)和中国科学院心理研究所心理健康重点实验室开发的中国情绪图片系统(Chinese Affective Picture System, CAPS;白露等,2004)。在上述每个实验中,被试均只需通过两类按键反应对刺激图片进行标准/偏差判断,而不管刺激的情绪特点。所得结果如下:1.人类对负性情绪刺激的效价强度变化尤为敏感,而对正性情绪刺激的效价变化相对不敏感,本论文将该效应命名为情绪效价强度效应。相关溯源分析提示,人脑对负性情绪刺激效价强度的特殊敏感性可能与右内侧颞叶,尤其与海马/杏仁核神经核团密切相关。2.与情绪效价强度效应相一致,不同效价的负性情绪对个体视觉新异性事件加工过程具有显著不同的影响,极端负性情绪对新异事件加工过程的影响显著大于中等负性情绪。该影响不仅表现在早期对新异事物的觉察和注意指向阶段,也存在于晚期个体工作记忆情景更新和反应选择阶段。3.尽管情绪效价强度效应的存在具有稳定性,由于适应性机制及负性偏向的存在,男女群体对极端负性刺激具有相似且十分显著的情绪脑反应,而女性群体对中等负性刺激的情绪感受性显著高于男性。女性对中等负性刺激增强的情绪感受性与女性右侧眶回有关。因此,女性对中等负性刺激更强的情绪感受性可能是女性负情绪识别优势的认知机制,而女性更大的眶回体积以及更好的眶回-杏仁核神经联系可能是该优势现象的神经机制(Gur et al., 2002)。4.进一步研究显示,在本研究条件下,从极端负性到极端正性-在人类情绪活动的全效价空间内-人类情绪感受性的性别差异仅表现为女性对中等负性刺激更强的情绪感受性,而男女两被试群体对各效价强度水平的正性刺激及极端负性刺激均具有相似的情绪感受性。在主观报告层面,女性对负性刺激发生比率的主观评估显著高于男性。由此可知,女性具有更强的负性情绪易感性,这很可能是无论文化与种族,各类情绪障碍发生率女性更高的重要机制,该现象的存在可能与女性右侧眶回有关。5.高外倾特质的个体对各效价强度水平的正性刺激均具有显著的情绪效应,而该类人群对中等负性刺激未表现出显著的情绪效应。与此相反,非外倾的控制组被试对各效价正性刺激均无显著情绪效应,而控制组被试对中等负性刺激具有显著的情绪效应。因此,更强的正性情绪易感性与降低的负性情绪易感性是外倾个体更高主观幸福感的重要机制。综上所述,人类的情绪活动存在效价强度效应:人类对负性刺激的效价强度变化更为敏感,且不同效价强度的负性情绪对高级认知活动,如视觉新异性加工过程具有显著不同的影响。该效应的存在与右侧海马/杏仁核有关。该效应的存在在具有相对稳定性的同时,其表现也显著受性别,外倾性等个体差异因素的影响。相比男性,女性对中等负性刺激具有更强的情绪感受性,这可能是负情绪识别女性优势的重要机制。男女群体对正性情绪及其效价强度的感受性无显著差异,但女性具有更强的负性情绪易感性可能是女性高情绪障碍比率的重要原因。外倾性人格特质在显著影响个体正性情绪感受性的同时,也显著影响个体对中等负性刺激的情绪感受性。增强的正情绪及其效价强度感受性与降低的负情绪感受性可能是高外倾性个体更高主观幸福感的重要机制。更多还原

【Abstract】 In addition to differences in category and valence polarity, the emotion people experience in life settings are also diverse in valence intensity. Anecdotal evidence suggests that negative emotions of diverse strength have different impact on human life and cognitive processes. This dissertation investigated the human sensitivity to valence intensity differences in emotional stimuli, and individual differences in brain susceptibility to emotional stimuli of diverse strength by manipulating the valence strength of emotional stimuli. Using the two-choice oddball task that is famous for ecological validity of emotional susceptibility studies, this dissertation was composed of 4 ERP studies. Study 1 investigated the human sensitivity to valence differences in emotional stimuli and the neural substrates underlying the emotional valence intensity effect. Study 2 investigated the influence of negative emotion of diverse valences on visual processing of rare novel events and its related temporal features. Using two ERP experiments, Study 3 investigated the neural mechanisms underlying the female advantage in identifying negative emotions, and neurophysiological correlates of the females’higher prevalence of affective disturbances by focusing on gender differences in emotional susceptibility to emotional stimuli of varying valences. Study 4 investigated how extraversion, a personality trait that describes the degree to which a person is outgoing, sociable, and interactive with other people, influences the human brain sensitivity to emotionally positive and negative stimuli, and the neural mechanism underlying extraverted people’s higher degree of personal happiness. All subjects recruited for these studies were healthy college students, and stimulus materials were emotional images selected from International Affective Picture System (IAPS) and Chinese Affective Picture System (CAPS). The results were as follows.1.The human brain is in particular sensitive to valence intensity changes in emotionally negative stimuli, while is relatively insensitive to valence intensity changes in positive stimuli. This effect is termed by the dissertation as emotional valence intensity effect, whose generation is likely to be mediated by the right hippocampus and amygdala complex.2.Consistent with description of emotional valence intensity effect, negative emotional contents of diverse strength have distinct impact on visual processing of rare novel events. This influence is observable not only at early attentional orienting but also at later context updating and response decisional stages. This suggests that the emotional valence intensity effect, to some extent, is stably existent and may be an inherent characteristic of the human emotional activity.3.While the existence of the emotional valence intensity effect is relatively stable, its manifestation is obviously influenced by individual difference factors such as gender, and emotion-related personality trait like extraversion. While males and females, generally speaking, are similar in emotional susceptibility to highly negative stimuli and to positive stimuli of diverse valences, females are more susceptible to negative stimuli of lesser saliency compared to males. This may be associated with the female advantage in identifying negative emotions and with the females’higher prevalence of affective disturbances. The increased brain susceptibility of females to mild negative stimuli is likely to be mediated by the right orbitofrontal cortex.4.Extraverted people are more emotionally reactive to positive stimuli compared to non-extraverted individuals, irrespective of the valence intensities of positive stimuli. On the other hand, extraverts are less susceptible to negative emotional stimuli of lesser saliency compared to control subjects. Therefore, the increased brain bias for positive emotional events and decreased susceptibility to moderately negative stimuli may account for the higher levels of subjective wellbeing in extraverts.In summary, there is an emotional valence intensity effect in the human emotional activity that the human brain is in particular sensitive to valence differences in negative stimuli while the brain is relatively insensitive to those in positive stimuli. This effect, possibly as an inherent characteristic of the human emotional activity, is stably existent, and the negative emotion of different strength has distinct impact on visual novelty processing. Despite its stability, biological sex, as well as the trait of extraversion, influences the manifestation of the emotional valence intensity effect, in particular, through modifying the human sensitivity to mild negative stimuli or to positive stimuli of diverse valences.更多还原