Directed Forgetting Of Negative Emotional Memory

Intentional forgetting of emotional memories refers to the phenomenon that people attempt to actively put the unwanted memories which are emotionally disturbing out of awareness. The intentional forgetting the unnecessary or unwanted memories can not only enhance the utilities of the memory systems, but also play an important role in keeping people in fit. Directed forgetting refer to the memory fault resulted from the forgetting instructions. The directed forgetting can be dived into item-method and list-method based on how to represent an instruction. The theory of directed forgetting phenomenon consist dual processes theory, set differentiation-selective search, selective encoding theory and inhibitory control theory. Researchers inclined to use the inhibitory control mechanism to explain the phenomenon of list-method directed forgetting, however, there is always a controversy of the mechanism of item-method directed forgetting, and some experts support the selective encoding mechanism while some agree to the inhibitory mechanism theory. Thus, there was no consistent theory of the mechanisms under the directed forgetting of emotional memories, whether people can intentionally control and forget these emotionally dominant stimuli.In this study, the different emotional materials, negative words and pictures, were used to explore the directed Forgetting. The results showed that though participants can forget the negative materials intentionally, the forgetting effect was smaller than the neutral ones. The presenting time of the words affected the directed forgetting effect of them, so it is reasonable to conclude that the selective encoding mechanism may contribute to the directed forgetting of the negative words. However, the directed forgetting effect of the images was not affected by the presenting time of them, so we conclude that the inhibitory mechanism may play an important part in their directed forgetting. In the second experiment, the Event-related brain potentials (ERPs) were used to explore the neural mechanism of the directed forgetting of negative images. ERPs are small changes in the electrical activity of the brain which is recorded with a temporal resolution in the order of a few milliseconds from multiple scalp locations. ERP is closely related to human cognitive processes. Scientists have used measures of brain activity to gain insights into these processes and revealed the nature of event-related potentials completely. We found that both the selective encoding mechanism and inhibitory mechanism play important role in the directed forting in the second ERP study. The forget instructions elicited an N2component which was related to inhibitory control, and the remember instruction elicited a P3component which represented the memory encoding process. All the results suggest that both the selective encoding mechanism and inhibitory control mechanism contribute to the directed forgetting. In addition, because the proceed processing of the negative images before the instructions presented, participants must pay more cognitive resource to inhibit the negative to be forgotten images. The larger N2component was elicited by the negative TBF images gave this supported this assumption and conclude that it is hard to intentional forgetting the negative items.