P3 response during short-term memory retrieval revisited by a spatio-temporal analysis

► ERPs during Sternberg tests with 3 and 5 memory set elements are investigated. ► P3 wave was split into two subcomponents in conditions with higher memory load. ► The early component had a right lateralized topography with onset at 200 ms. ► Late component had the typical P3 topography with a latency parallel to reaction times. ► Early component reflects the start of the memory scanning followed by the decision.