Retrieved context and the accumulation of episodic memories

In the study of human memory, it is often useful to distinguish episodic memory from semantic memory. Whereas episodic memory is defined as information associated with its spatiotemporal context, semantic memory refers to longstanding knowledge and lacks an autobiographical component. In list learning experiments, it is assumed that participants begin with a rigid set of semantic memories and form new episodic memories over the course of the experiment. Presumably episodic memories accumulate over time and across presentations to give rise to semantic memories, but many questions remain concerning this process. This work examines how episodic memories accumulate across longer time scales and multiple presentations by extending classic work of within-list effects of lists comprised of once-presented items. The first two research chapters examine how memories accumulate at encoding by comparing presentations of once-presented and twice-presented items. The next chapter examines how memories accrue at retrieval to form compound cues in free recall. Then I examine how memories accrue during an experimental session by considering across-list interference, recency, and contiguity effects. Lastly, I consider the influence of episodic memories on time scales even longer than an experiment by examining the influence of frequency of usage in free recall of word lists. All of the results are consistent with retrieved-context theory, which posits that a slowly changing temporal context representation incorporates an item\u27s contexts from its previous presentations, and that context serves as a retrieval cue. Thus, this theoretical framework provides a comprehensive theory of the accumulation of episodic memories