Causal coherence improves episodic memory of dynamic events

“Episodes” in memory are formed by the experience of dynamic events that unfold over time. However, just because a series of events unfold sequentially does not mean that they are related. Sequences can have a high degree of causal coherence, each event connecting to the next through a cause-and-effect relationship, or be a fragmented series of unrelated occurrences. Are causally coherent events remembered better? And if coherence leads to better recall, which attributes of episodic memories are particularly affected by it? Past work has investigated similar questions by manipulating the causal structure of language-based, narrative stimuli. In this study, across three experiments, we used dynamic visual stimuli showing unfamiliar events to test the effect of causal structure on episodic recall in a cued memory task. Experiment 1 found that the order of three-part causally coherent sequences of events is better remembered than that of fragmented events. Experiment 2 extended this finding to longer sequences and further demonstrated that causal structure is not confounded with low-level characteristics of the stimuli: Reversing the order of coherent stimuli led to task performances indistinguishable from those on fragmented stimuli. Experiment 3 replicated the results of improved order recall from the previous experiments and additionally showed that recall of causally relevant details of coherent stimuli is superior to recall for details of focal events in fragmented sequences. In sum, these findings show that the episodic memory system is sensitive to the causal structure of events and suggest coherence usually leads to better recall.