知觉负载对负性分心面孔的知觉加工和记忆的影响

本研究采用视觉搜索和意外再认记忆任务,结合事件相关电位技术,考察知觉负载对负性分心面孔的知觉加工和记忆的影响。在视觉搜索任务中,行为上恐惧分心面孔在高负载下干扰任务。ERP结果上,恐惧比中性分心面孔诱发更大的N170和N250;在低负载下恐惧比中性分心面孔诱发更大的N700,在高负载下没有差异。在意外再认记忆中,个体对低负载下的恐惧分心面孔表现出记忆。这些结果说明负性分心物在早期是自动化加工;晚期加工受知觉负载的调节,负载越低对负性分心物的过滤越少,存在对负性分心物的记忆偏向。

The effect of perceptual load on processing and memorizing negative facial distractor

The processing of facial expression has been well studied. However, how facial expression is processed and memorized when it is presented outside the focus of attention is little known. Previous results of negative distractor processing were contradicted. Some studies found that processing of emotional distractor is resistant to perceptual load, whereas other studies found that emotional distractor processing is modulated by perceptual load. Interestingly, two recent studies have shown that the processing of emotional charged distractor are both automatically and depending on perceptual load. However, the temporal information of automatically and load depending processing of emotional charged distractor, is little known. Whether the individual can detect a distractor during early phase automatically, and suppress the distractor under high perceptual load at late phase of processing. To this end, we investigate how perceptual load affects facial expression distractor processing at different phase of encoding by using event-related potential methods. In ERP studies, the N170 and N250 are two early components which sensitive to the attentional resources and facial expression, while the N700 is a late component which related to saving stimulus into long-term memory when stimulus is disappear. According to previous studies and perceptual load theory, we hypothesized that facial expression distractor would process automatically in the early phase, while it modulates by perceptual load in the late phase. We expect that N170 and N250 would modulate by distractor valence but not perceptual load, while N700 would modulate by the interaction between perceptual load and distractor valence. Participants were asked to perform a letter search task which adopted from (Jenkins et al., 2005), followed by a surprise recognition task for facial expression distractor. In the letter search task, a letter string superposed on a facial distractor, participants were required to detect specific character and make response. Perceptual load (low, high) and distractor valence (neutral, fearful) were manipulated. In the surprise recognition task, participants were asked to judge whether the face was presented in the letter search task, half of the faces were presented in the letter search task, half of the faces were not presented before. In the letter search task, behavioral results showed that fearful distractor, relative to neutral distractor, interfere with visual search performance in the high perceptual load condition, while this interference effect was not significant in low perceptual load condition. ERP results showed that fearful distractor, relative to neutral distractor, elicit larger N170 and N250. The N170 and N250 were not modulated by perceptual load. In contrast, the N700 which related to post-stimuli processing and learning was modulated by the interaction between perceptual load and distractor valence. Fearful distractor elicited larger N700 than neutral distractor under low perceptual load, whereas there was no significant difference between fearful and neutral distractor under high perceptual load. The memory performance was mimic the N700 results, participant recognized fearful distractor better than neutral distractor under low load, whereas there was no significant difference under high load. These results suggest that the processing of facial expression distractor affected by perceptual load at different stage during encoding phase. In the early stage, the facial distractor is process automatically, whereas in the late stage, the post-stimuli processing is modulated by perceptual load and valence. Low perceptual load leads to less filtering of task irrelevant negative information, which induced a memory bias for negative distractor.