The Effect Of Expectation Violation On Short-term Source Amnesia

Source amnesia means that people often have complete memory of the content of an event,but lack the memory of the source information associated with it.It is traditionally believed that source amnesia could only be observed in the context of long-term memory,but not in working memory(WM)or short-term memory,as we share the intuition that the source information of an item that we just encountered is always available.However,a recent study(Chen,Carlson,& Wyble,2018)challenged this common sense by showing the source amnesia for visual stimuli in the context of working memory.The results showed that participants could not accurately report source information in the surprise test if they did not expect to be asked to report it before.It was indicated that WM was highly selective for processing information and the task-irrelevant source information of visual stimuli was not automatically encoded into WM.A subsequent study(Chen,Yan,Zhu,Wyble,Eitam,& Shen,2019)established a double-surprise paradigm and found that after the expectation violation,the selectivity of information storage in working memory was weakened and the task-irrelevant item information was also automatically stored in WM.However,it is not clear whether the expectation violation would cause the source information to be automatically stored in WM.Moreover,Chen and his colleagues(2019)only used the surprise test to induce the expectation violation,and it has not been clear whether this method was specific.Therefore,the present study adopted a variety of methods to induce the expectation violation,such as the surprise test,color change,location change,and tone change of background sound,in order to systematically investigate the moderating effect of the expectation violation on short-term source amnesia,and reveal its underlying mechanism.The following five experiments were included:(1)Experiment 1 repeated short-term source amnesia phenomenon.This experiment was used as a control experiment to compare with other expectation violation experiments.(2)On the basis of Experiment 1,Experiments 2-4 used double surprise tests,color change,and location change respectively to induce the expectation violation,in order to investigate the effect of the expectation violation on short-term source amnesia.The results showed that compared with control experiment(Experiment 1),the source memory performance in the surprise trials of Experiments 2-4 was significantly improved,indicating that the expectation violation weakened the information selectivity of WM,which caused that the task-irrelevant source information was automatically stored in WM and the source amnesia phenomenon was erased.(3)For the results of the above experiments,a possible hypothesis was that the improving source memory performance of the target stimulus in the surprise test was due to the fact that the expectation violation manipulation in Experiments 2-4enhanced the participants’ attention level to the target stimulus,rather than caused by the expectation violation itself.To separate the effect of attention and expectation violation,Experiments 5a and 5b used the sudden change of task-irrelevant auditory stimuli to induce the expectation violation.This manipulation drew attention away from the target stimulus while inducing the expectation violation.The results showed that compared with the control group,the expectation violation still had a significant moderating effect on short-term source amnesia,which indicated that this moderating effect was caused by expectation violation itself,rather than by the increase of attention.In conclusion,the present study showed that the short-term source amnesia was a robust effect and demonstrated that this phenomenon was moderated by the expectation violation.The expectation violation weakened the information selectivity of visual WM and allowed task-irrelevant source information to store into WM.