The relationship between the right frontal old/new ERP effect and post-retrieval monitoring: Specific or non-specific?

Abstract

Post-retrieval processes are thought to be engaged when the outcome of an attempt to retrieve information from long-term memory must be monitored or evaluated. Previous research employing event-related potentials (ERPs) has implicated a specific ERP modulation – the ‘right frontal old/new effect’ – as a correlate of post-retrieval processing. In two experiments we examined whether the right frontal effect is specifically associated with processing of the products of an episodic retrieval attempt. During study, subjects in both experiments made one of two semantic judgments on serially presented pictures. In experiment 1, one study phase was followed by a source memory task, in which subjects responded ‘new’ to unstudied pictures and signaled the semantic judgment made on each studied picture. A separate study phase was followed by a task in which the studied items required a judgment about their semantic attributes. Robust right frontal effects were elicited by old items in both tasks, indicating that the effects are not selective for the monitoring of the content of information retrieved from episodic memory. In experiment 2, separate study phases were followed by test phases where semantic judgments were made either on old items (as in experiment 1), or on new items. Right frontal effects were elicited by whichever class of items, old or new, required the semantic judgment. Together, these findings indicate that the right frontal old/new effect reflects generic monitoring or decisional processes, rather than processing dedicated to the evaluation of the products of an episodic retrieval attempt.