Characterizing the ERP Old-New effect in a short-term memory task

The early and late components of the event-related potential (ERP) Old-New effect are well characterized with respect to long-term memory, and have been associated with processes of familiarity and recollection, respectively. Now, using a short-term memory paradigm with verbal and non-verbal stimuli we explored the way that these two components respond to variation in recency and stimulus type. We found that the amplitude of the early component (or frontal N400, FN400) showed Old-New effects only for verbal stimuli, and increased with recency. In contrast, the later component (or late positive component, LPC) showed Old-New effects across a range of stimulus types, and did not scale with recency. These results are consistent with the way that these same ERP components have been characterized in long-term memory, supporting the idea that some of the same processes underlie long- and short-term item recognition. The sizeable literature on stimulus repetition’s effect on the event-related potential (ERP) shows that ERPs evoked by previously–experienced stimuli are more positive-going than ERPs evoked by new stimuli (for reviews, see Johnson, 1995