Remember to forget: ERP evidence for inhibition in an item-method directed forgetting paradigm

The present study examined the electrophysiological correlates of intentional forgetting using the item-method directed forgetting paradigm. Participants (N = 23) studied a series of words each followed by either a “remember” cue (TBR) or a “forget” cue (TBF) and then undertook an old/new recognition memory test for which they were requested to endorse studied items regardless of original remember/forget status. Event-related potentials time locked to the cues were examined as a function of subsequent recognition-memory accuracy. Results showed that TBR and TBF cues elicited Dm or subsequent memory effects that differed in scalp distribution and polarity, suggesting activation of fundamentally different encoding operations for the respective sets of items. Additionally, analyses that examined the processes underlying successful implementations of intentions to forget (i.e., TBF-miss vs. TBR-miss) and intentions to remember (i.e., TBR-hit vs. TBF-hit) revealed that in case of unwanted information a frontal inhibition mechanism is engaged to stop processes associated with intentional memory formation. These results counter the possibility that directed forgetting reflects only the more elaborate encoding of TBR than TBF words and, instead, implicate the existence of an active inhibitory mechanism directed at TBF words once the forget cue is presented.

Research highlights
► Dm effects for remember and forget cues differ in scalp distribution and polarity.
► Intentional but not unintentional forgetting elicits a sustained left-frontal positivity.
► Directed forgetting implicates an active inhibitory mechanism that stops memory formation.