负面身体自我女性对身体信息的记忆偏向： 来自ERP研究的证据

采用事件相关电位（ERPs）技术探讨了负面身体自我女性（大学生）对胖-瘦两类身体图片进行再认时的脑内时程动态变化。结果发现，相对于控制组（正常女大学生），胖负面身体自我女大学生在750~800ms的时间窗口内，“胖图”比“瘦图”诱发出一个更正的ERP波形，差异波的地形图显示该正成分在中前部有更强的激活。进一步对差异波作偶极子溯源分析，结果发现，该正成分主要起源于右侧枕叶附近。这似乎表明，右侧枕叶的激活与身体自我信息的出现有关，与负面身体自我图式的体验有关

Memory Bias toward Body Information in Women with Negative Physical Self: Evidence from an ERP Study

Behavior research evidence has shown that people with a negative physical self have a cognitive bias with a longer reaction time to body information than to neutral information. Chen (2005) indicated that participants with a fat negative physical self have a cognitive preference and selectively perceived body information; however, the underlying mechanism of this phenomenon has not been discussed further. Therefore, the aim of this study is to reveal the brain mechanism of negative physical self by using the event-related potential (ERP) technique. ERPs were recorded to examine the electrophysiologic correlates of the recognition of body pictures. After completing the Negative Physical Self Scale (NPSS), based on their scores on the NPSS-Fat, 28 participants were assigned to the control group (14 normal females) or experimental group (14 females with a negative physical self). During phase one, 288 pictures were presented to the participants. The participants were asked to respond when the target picture appeared. Phase two involved the random presentation of 576 pictures, which consisted of the 288 pictures already presented in phase one and 288 new ones. The participants were requested to judge whether or not the pictures had appeared in phase one. According to the participants’ responses, the electroencephalography (EEG) of the responses to “fat pictures,” “thin pictures,” and “neutral pictures” was separately overlapped. The averaged epoch for an ERP was 1200 ms including an epoch of 200 ms for the pre-answer baseline. ERP waveforms of both groups showed that both fat pictures and thin pictures elicited a more positive ERP deflection than did neutral pictures in the time interval of 250~1000 ms. Moreover, we found that the fat pictures elicited a more positive ERP deflection than did the thin pictures in the time interval of 750~800 ms only in the experimental group. A voltage map of the difference wave of the fat and thin pictures showed strong activity in the central frontal region. The dipole analysis (brain electrical source analysis (BESA) software) localized the generator of the difference wave (fat pictures minus thin pictures) in the right occipital lobe. In the current study, it is indicated that the difference wave of the fat and thin pictures mainly activated the right inferior occipital gyrus, which was consistent with Uddin et al.’s (2005) functional magnetic resonance imaging (fMRI) findings that the same brain region was activated by images of one’s own face. A possible interpretation might be that body information may have activated physical self-schema in participants with a negative physical self, which might be reflected by the activation of the right inferior occipital gyrus