Electrophysiological correlates of individual differences in strategic retrieval processing.

Processes engaged when information is encoded into memory are an important determinant of whether that information will be recovered subsequently. Also influential, however, are processes engaged at the time of retrieval, and these were investigated in four experiments using event-related potentials (ERPs). Contrasts were made between ERPs elicited by new (unstudied) test items in distinct tasks, the assumption being that these contrasts index operations that are engaged in service of retrieval and which vary according to the demands of different retrieval tasks. Functional accounts of these retrieval processing operations, termed throughout as strategic retrieval processes, assume that they influence the accuracy of memory judgments. The experiments reported here comprise the first direct tests of this assumption. In Experiment 1, the magnitude of the differences between new item ERPs from retrieval tasks with distinct retrieval requirements were correlated positively with response accuracy. This pattern was interpreted as indicating that participants who made relatively more accurate responses did so by prioritising the recovery of different types of information in each of the two retrieval tasks. Encouraging participants to adopt this approach in Experiment 2, however, did not lead to changes in response accuracy, or to ERP modulations comparable to those obtained in Experiment 1. In Experiments 3 and 4, ERP evidence for the degree of strategic retrieval processing was again related to response accuracy. These two experiments had different retrieval requirements, and the scalp distributions of the differences between the new item ERPs differed across the experiments. These findings therefore provide further support for a relationship between strategic retrieval processes (as indexed by differences between new item ERPs) and response accuracy, whilst also emphasizing that the specific retrieval processes engaged vary according to task demands. These findings provide new insights into how and when strategic retrieval processes are engaged in service of accurate memory judgments