|Alternative Title||The effect of stress on attention bias towards emotional stimuli|
|Thesis Advisor||张侃 ; 张亮 ; 吴健辉|
|Place of Conferral||北京|
|Keyword||注意偏向 急性应激 慢性应激 创伤后应激障碍 事件相关电位|
研究一中主要采用事件相关电位技术（ERP）考察急性应激了对注意偏向的影响。61 名男性在校大学生参与了实验。他们被随机分配到应激组（40 人）和控制组（21 人）。特里尔社会应激测试（Trier social stress test，TSST）被用来诱发被试的心理社会性应激，主观的正性负性情绪量表和客观的唾液皮质醇、心率用来作用应激反应的指标。点探测任务被用来测量负性注意偏向。研究结果发现，TSST 成功诱发了个体的应激反应，体现在应激组比控制组的负性情绪得分更高，唾液皮质醇浓度更高，心率更快。在行为正确率上，控制组被试表现出对愤怒面孔的注意偏向，在应激条件下负性注意偏向受到了抑制，被试表现出注意回避模式。脑电结果表现出与行为结果相似的模式。控制组在一致条件的P100 潜伏期短于不一致条件，表现出对愤怒面孔的注意偏向；而在应激条件下，这种注意偏向消失了，表现为一致和不一致条件的P100 潜伏期没有差异。另外，研究还发现急性应激会损害个体对面孔线索的加工，同时还能影响个体的注意定向和注意控制，这主要体现在应激组被试的N170 和P300 波幅更小。
研究二主要通过ERP 技术探索了慢性应激对注意偏向的影响。该研究中，共有60 名男性在校大学生参与了实验。根据被试在知觉压力量表上得分的中位数将被试分成高应激组（32 人）和低应激组（28 人）。研究二采用了与研究一相同的点探测任务来评估个体的注意偏向。结果发现，个体对威胁刺激的注意偏向不受慢性应激水平高低的影响。另外，研究二也发现高应激组的P300 波幅显著小于低应激组，说明慢性应激也会损害个体的注意控制和注意定向。
研究一和研究二针对的都是健康的普通人。研究三则旨在通过ERP 技术考察经历过重大应激事件（地震）后出现临床生理病理症状的人群的注意偏向特点。93 名经历过2008年汶川地震的被试参与了实验，其中PTSD 组44 人，non-PTSD组49 人。情绪Stroop 任务用来评估个体的注意偏向。结果发现闯入症状和回避症状都能显著预测个体对负性面孔的注意偏向，主要体现在这两个维度都与N200 差异波相关显著。另外，研究三还发现与non-PTSD 组相比，PTSD 组的P200 波幅更大，N200 波幅更小。
|Other Abstract||People always have shorter response time to negative or threatening stimuli and their attention isalso allocated to these stimuli much more when compared to neutral stimuli.This phenomenon is called attentional bias to negative or threatening stimuli. Many factors can influence attentional bias. Stress is common in our daily life and puts profound influence on emotional processing and cognitive functions. Different stress, such as short-term and mild stress, long-term and chronic stress, as well as major stressful event (e.g. earthquake) and so on, may had different effect on cognitive function. Previous studies had examined the effect of stress on attentional bias to threat with behavioral method. But, how and at which stage did these different stresses affect attentional bias was still unknown. The present study wanted to address these questions referred above.|
Study 1 aimed to investigate the effect of acute stress on attentional bias with both event related potentials (ERPs) and behavioralmethods. Sixty-one undergraduate male students were randomly allocated to a stress (Trier Social Stress Test, TSST) or nonstressful control condition and then administered a modified dot probe task. Behavioral results demonstrated the control group had a higher accuracy in the valid condition than invalid condition, while the stress group showed a reverse pattern. For ERP data, the stress group showed a less negative N170 evoked by face pair onset than the control group. For ERPs evoked by target onset, shorter P100 latencies for valid trials than invalid trials only appeared in the control group, suggesting a rapid, adaptive response to potential threats. This effect, however, disappeared in the stress group, suggesting suppressed attentional bias under acute stress. In addition, the stress group showed a decreased P300 amplitude to target for both valid and invalid condition in contrast to the control group. These results suggested that acute psychosocial stress suppressed negative attentional bias as revealed by both ERP and behavioral data, and reduced engagement of attention orienting and attentional controlto targets.
Study 2 aims to explore how chronic stress affected attentional bias with ERP and behavioral methods. Sixty male undergraduate students participated in this study. The division of high stress (N = 32) and low stress ( N = 28) was according to the median score on perceived stress scale(PSS). The same modified dot probe task as study 1 was adopted to assess individual’s attentional bias to threat. For behavioral results, we found significant validity effect, showing valid condition had higher accuracy on nogo trials than invalid condition, meaning attentional bias to angry faces. This effect was unrelated to group difference. For ERP data, the present study didn’t found any significant group difference or validity effect, as well as interaction of the two variables, on P100 component. But we confirmed the finding of study 1 that the engagement of attentional orienting and attentional control were impaired under stress, as revealed by reduced P300 amplitude in high stress group compared to low stress group.
Only healthy individuals were included in Study 1 and study 2. Study 3 wanted to examine the time course of attentional bias in participants with post-traumatic stress disorder (PTSD) using ERP. Emotional Stroop task was used to evaluate attentional bias to threat. Participants experienced Wenchuan earthquake, including participants with PTSD (N = 44) and without PTSD (non-PTSD, N = 49), were included in study 3. The results found that intrusion symptoms was negatively related to N200 difference wave and avoidance symptoms was positively related to N200 difference wave. In addition, this study also found that PTSD group had enhanced P200 and attenuated N200 amplitude relative to non-PTSD group. These findings suggested that the severe of PTSD symptoms correlated to individual’s attentional bias to threat.
|蒋彩虹. 应激对注意偏向的影响[D]. 北京. 中国科学院研究生院,2015.|
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