关键词: 短时记忆, 编码, 记忆保持, 记忆提取, 负性情绪, 厌恶

Abstract:

Emotional memory enhancement effect has been verified in various memory studies using negative material. So far as we know, four studies demonstrated that disgusting stimuli are associated with a higher recognition accuracy in memory task, compared to fearful stimuli. However, the underlying neutral mechanism is still unclear. Since emotional arousal and valence are two important factors showing emotional memory enhancement effect, they should be counterbalanced between disgusting and fearful material when the latter two emotions are compared in memory.
The current study used event-related potential (ERP) to investigate different effect of disgust and fear on memory encoding, retention and retrieval. In particular, the following ERP components were examined: the P1, N170 and P3 both during memory encoding and retrieval, and the negative-going slow wave (NSW) during memory retention. A total of 60 healthy adults were recruited to participate a delayed recognition task, among whom ERP data were collected from 30 participants.
It is found that the recognition performance was better for disgusting faces than fearful faces. During memory encoding, fearful faces evoked larger P1 amplitudes while disgusting faces evoked smaller P1 amplitudes, both compared to neutral faces. Similar ERP pattern was found in N170, i.e., fearful faces evoked larger N170 while disgusting faces evoked smaller (but not significant) N170. In contrast, the P3 component during encoding showed largest amplitudes in disgusting condition. During memory retention, the NSW was the largest for disgusting faces, smaller for fearful faces, and the smallest for neutral faces. During memory retrieval, the P1 pattern was the same as during encoding period. However, the N170 showed comparable amplitudes for fearful and disgusting faces, while the N170 evoked by neutral faces was the smallest. More importantly, the P3 was larger in the disgusting condition than in the fearful condition. In addition to emotion effect, this study also found the effect of memory load. High memory load resulted in lower recognition accuracy, longer response time, smaller P3 (both during encoding and retrieval) and N170 (during encoding), as well as larger N170 (during retrieval) and NSW (during retention), as compared to low memory load. Furthermore, the emotion effect on recognition accuracy, the P1, N170 and P3 during encoding was enlarged at high memory load.
This study demonstrated that three mechanisms may contribute to the enhanced memory for disgusting than fearful stimuli. The first is that increased attention is allocated by top-down control system to elaborately evaluate disgusting stimuli at the stage of memory encoding (reflected by encoding P3). The second is that extra cognitive resources are employed for disgusting stimuli during memory rehearsal and retention (reflected by retention NSW). The third is that increased effort is made to retrieve the memory regarding disgust (reflected by retrieval P3). The current finding could help to further understand the cognitive mechanism underlying emotional memory enhancement effect.

Key words: short-term memory, memory encoding, memory retention, memory retrieval, negative emotion, disgust