Intentional forgetting might be more effortful than remembering: an ERP study of item-method directed forgetting

This study recorded ERPs while participants engaged in a procedure that combined semantic priming and item-method directed forgetting, aiming to investigate the issues of whether intentional forgetting demands cognitive efforts and modulates the semantic processing of to-be-remembered (TBR) and to-be-forgotten (TBF) items. Participants made lexical decisions to semantically related or unrelated prime and target words. A Remember/Forget cue, presented between the prime and target, designated the prime as TBR or TBF. When the cues were shown for 500 ms, targets preceded by Forget cues yielded a smaller P200 wave than those preceded by Remember cues. Furthermore, the topography of the N400 effect was different for targets preceded by Remember and Forget cues. The cues did not modulate the ERPs of the targets when they were shown for 1500 ms. Because P200 is sensitive to attention influence and the N400 effect reflects semantic processing, we conclude that forgetting is more effortful than remembering and that the semantic processing is different for TBR and TBF items. Nevertheless, there is a temporal limitation for the Remember/Forget cues to modulate the semantic processing and attentional resources in item-method directed forgetting.