| dc.description.abstract | When experiencing a perceptual or conceptual context shift (i.e., experiencing an event boundary), the continuous information we perceived is segmented into discrete events in our daily life. However, whether the change of emotional context also has the same process on our event memories remains unclear. To investigate this question, we manipulated the emotional context images and temporal breaks on our four study-test behavioral experiments and one EEG experiment. Participants studied a series of emotional context images with or without temporal break followed by an incidental recognition task. In experiment 1, participants experienced positive and negative context change along with temporal break. The result showed a significantly better recognition memory for the post-boundary items than the others, indicating that people would perceive an event boundary when they experienced an emotional context change with a temporal break. However, whether the pure emotional context shift or pure temporal break is sufficient for segmenting ongoing information into events remains unclear. Therefore, participants encountered only temporal break with the neutral context in experiment 2 and only positive and negative context shift in experiment 3. These results revealed no boundary enhancement effect when participants only experienced temporal break while the boundary enhancement effect for negative pictures was diminished when participants encountered pure emotional context shift. After comparing Experiment 3 with Experiment 1, we found that the difference between these two experiments was not caused by temporal breaks. Later, we considered whether disturbing encoding phase would impact the perception of event boundaries. In experiment 4, we increased the difficulty of the gap judgment task and found that there was no event boundary enhancement effect. However, after comparing Experiment 4 with Experiment 3, we found that the difference of the results between these two experiments was not caused by increasing the study difficulty. From two comparisons, we found the event boundary enhancement effect was specific to the positive context, thus, we consider whether this enhancement was influenced by the prior negative pictures. To address this issue, we replaced the positive pictures with neutral pictures to test in a more realistic way in EEG experiment. The behavioral results showed that there was no boundary enhancement effect, suggesting that the negative stimuli did not facilitate the later stimuli. For ERP results, we found a large N300 for both neutral and negative pictures, a late LPP started from 900 and lasted to 1900 ms, and a more negative waveform for post-boundary items than pre-boundary items in the time window from 200 to 1900 ms. Besides, the subsequent recognition memory was better for negative pictures than neutral pictures and there was a subsequent memory effect for post-boundary pictures in the time window from 1600 to 1900 ms but not for pre-boundary pictures. In summary, our behavioral results indicated that emotional context shift could be perceived as event boundaries in conditions that the context changed from negative to positive. Neural physiological results suggested that there might involve different processing for pre-boundary and post-boundary. | en_US |