Stuck in the past: neural events that predict intrusions from prior trials

Neurologically intact adults perseverate in immediate serial recall, intruding items from a previous trial into the current response. We applied the electroencephalogram/event-related-potential subsequent-memory paradigm to immediate serial recall to investigate the causes of these errors. In line with previous studies using this paradigm, results revealed that words that were correctly recalled elicited a greater frontal positivity during encoding when compared with words that were either perseverated over or not produced for some other reason. More surprisingly, differences were also found at encoding between the words perseverated into the subsequent response and words that were not perseverated. These findings support a theory stating that abnormalities in both how the current target and the previous trial are processed can contribute to perseveration errors. These results inform existing theories of immediate serial recall and theories of the control of irrelevant information.