An electrophysiological investigation of factors facilitating strategic recollection

Episodic memory is thought to be mediated by executive processes that facilitate the retrieval of task-relevant information at the expense of irrelevant information. The exclusion task [A process dissociation framework: Separating automatic from intentional uses of memory. Journal of Memory and Language, 30, 513-541, 1991] can be used to explore these processes. In this task, studied items from one source ("targets") are endorsed on one response key, whereas new and studied items from another source ("nontargets") are rejected on another key. Herron and Rugg [Strategic influences on recollection in the exclusion task: Electrophysiological evidence. Psychonomic Bulletin and Review, 10, 703-710, 2003] reported that nontargets elicited the ERP correlate of recollection (the "left parietal old/new effect") when target accuracy was low, but not when it was high. Their explanation for this was that participants only focused exclusively on the recollection of target information when the likelihood of target recollection was high, as under these conditions this strategy is one that that will give rise to accurate task performance. The fact, however, that targets were encoded in different tasks in the high- and low-accuracy groups means that the results can also be explained in terms of the encoding operations performed at study rather than in terms of target accuracy. This study was designed to distinguish between these competing accounts. All targets were encoded elaboratively. Target accuracy was reduced in one condition with a 40-min study-test interval. Nontargets elicited no left parietal effect in either condition, suggesting that target-specific strategic retrieval is facilitated by certain classes of encoding operations rather than simply high target accuracy per se.