Event Segmentation Reveals Working Memory Forgetting Rate

Abstract

It is evident that past experiences are remembered as episodes although the world is encountered as a continuous flow of events. Working memory plays a key role in tracking and segmenting the flow of events during encoding. Despite that generally event segment is triggered by perception of a salient event, empirical data shows that the number of identified segments is variable across a tested population. It is yet unclear which aspect of working memory – capacity or forgetting rate - is related to individual variability in segmentation. Here, we used computational modeling to estimate the working memory capacity and forgetting rate of healthy adults performing an association learning task, and we determined a relationship between working memory and event segmentation that was determined of three movies with different storylines. The results revealed a U-shaped relationship between forgetting rate and event segmentation, so that the individuals who reported either a very low (coarse- segmenters) or a very high (fine-segmenters) number of events had a faster forgetting rate. The results from the long-term memory tests suggested that two different strategies were used by the fine- and coarse-segemneters. The coarse-segmenters had better recognition of temporal order of events and benefited from the storyline of the movie, specifically for temporally distant events, in contrast to the fine-segmenters, who performed better at free recall. Accordingly, the variability in event segmentation was related to the variability in utilizing working memory and long-term memory systems.