Electrophysiological correlates of successful episodic retrieval were measured in an experiment where participants switched frequently between two different episodic retrieval conditions. They completed three trials of each condition before switching to the other condition. The key contrasts were between neural indices of successful retrieval that were separated according to the number of successive trials of the same condition that had been completed. An electrophysiological correlate of recollection--the left-parietal event-related potential (ERP) old/new effect--was smaller on the first and second trial than on the third successive trial that participants completed for each condition. This ERP old/new effect is assumed to index the extent to which recollection has occurred, and this outcome suggests that control over recovery of task-relevant episodic content is compromised when additional cognitive demands are imposed around the time of retrieval.