Requirements at retrieval modulate subsequent memory effects: An event-related potential study.

Neural indices of memory formation can be acquired by contrasting activity during study for items that are remembered or forgotten on a subsequent memory test. These "subsequent memory" effects vary with the stimulus types that are encoded, how they are encoded, the correspondences between study and test materials, and the time intervals between study and test phases. We investigated whether event-related potential (ERP) subsequent memory effects also vary with the content people must retrieve. Participants saw words on the left/right side of fixation, and made a drawing difficulty or pleasantness judgment to each. In separate test phases, participants were asked to remember study screen location, or which task judgment had been made. The ERP subsequent memory effects from these two tasks were functionally distinct, demonstrating for the first time that ERP subsequent memory effects dissociate according to what people are trying to retrieve.