Not all memories make people comfortable. People can forget unwelcome memories by retrieval suppression, that called suppression-induced forgetting. The Think/No-think paradigm employed to investigate suppression-induced forgetting includes Think, No-think, and Baseline conditions, respectively. If the recall accuracy of No-think cue-target word pairs is reduced significantly compared to Baseline cue-target word pairs, means suppression-induced forgetting is induced. As for the mechanism of suppression-induced forgetting, interference theory indicates that, suppression-induced forgetting is due to new association created with cue items interferes with the retrieval of old association. In contrast, inhibition theory claims that, suppression-induced forgetting is the result of impaired retention and accessibility of target memory by participants inhibit unwanted memories from entering consciousness. Based on inhibition, executive deficit hypothesis believes that, the differences of suppression-induced forgetting among individuals deserve from variant executive control ability. At present, the stability of suppression-induced forgetting is still controversial. For the purpose, the current paper summarizes prior papers and finds that, suppression-induced forgetting effect is mainly affected by the suppression parameters, valence and arousal level of experimental materials, anticipatory effect and individual differences and so on.
Firstly, the suppression parameters consists of suppression duration and suppression times. Specifically, in terms of suppression duration, when the duration of Think/No-think phase is proper, if duration of a NT trial is set within 5s, suppression-induced forgetting may be detected, and it maybe increasingly enhance follow suppression duration increases. As far as suppression times is concerned, the number of suppression may need to set as at least 8 or more, only in that case, suppression-induced forgetting will tend to be stable. Secondly, the suppression-induced forgetting effect of negative emotional memories is stronger than neutral emotional memories. The possible reason is due to negative emotional memories are more susceptible to stronger inhibitory control compared to neutral memories. For the positive emotional memories, it can also induce suppression-induced forgetting. However, it is harder to forget those memories associated with positive emotion. Interestingly, positive emotional memories with high arousal are easily suppressed, while negative emotional memories are suppressed difficultly regardless of arousal. In addition, suppression-induced forgetting effect can be increased by means of participants make the preparation for retrieval suppression of target memory when anticipatory cue appears. Finally, suppression-induced forgetting is increasingly improved from children (8 years old) to adults, even not reduced markedly in old age. However, for the impaired memory suppression ability, depression and post-traumatic stress disorder patients forget negative emotional memories hard. Notably, stronger the executive control ability is, stronger the suppression-induced forgetting is. Therefore, executive control ability deficit maybe the reason why suppression-induced forgetting effect disappear for depression and post-traumatic stress disorder patients, too. In future, researches should investigate the effect of connective strength within memory control network on suppression-induced forgetting, especially for post-traumatic stress disorder and depression patients. Beyond that, researches should further examine the effects of emotional arousal and all kinds of negative emotions on suppression-induced forgetting, to explore whether insomnia and sleep deprivation can improve suppression-induced forgetting effect, and illustrate the relationship between inhibitory control and REM sleep duration and so on.
Key words
Suppression-induced forgetting /
experimental factors /
individual differences /
memory control network