Proceedings of the Annual Meeting of the Cognitive Science Society

Events appear to be represented distinctly in memory in large numbers at a fine grain, even in tasks in which memory retention is not a primary performance measure. In Experiment 1, participants classified character strings in sequences governed by randomly-alternating instructions. Response times were fastest near the start of a sequence, slowed gradually throughout the sequence, then sped up again near the start of the next sequence. This speedup and gradual slowdown were modeled in the ACT-R architecture as a combination of priming and interference effects in episodic memory. The model correctly predicts the absence of these effects in Experiment 2. in which the instruction must be inferred from the trial stimulus and hence is not a source of priming. These findings suggest (a) that episodic encoding is a pervasive side effect of cognitive performance; (b) that elements of episodic memory interact through priming and interference—effects traditionally associated with semantic memory; and (c) that brief interruptions of task performance have more complex effects than previously documented.