Can We Retrieve the Information Which Was Intentionally Forgotten? Electrophysiological Correlates of Strategic Retrieval in Directed Forgetting

Abstract

Retrieval inhibition hypothesis of directed forgetting effects assumed TBF (to-be-forgotten) items were not retrieved intentionally, while selective rehearsal hypothesis assumed the memory representation of retrieved TBF (to-be-forgotten) items was weaker than TBR (to-be-remembered) items. Previous studies indicated that directed forgetting effects of item-cueing method resulted from selective rehearsal at encoding, but the mechanism of retrieval inhibition that affected directed forgetting of TBF (to-be-forgotten) items was not clear. Strategic retrieval is a control process allowing the selective retrieval of target information, which includes retrieval orientation and strategic recollection. Retrieval orientation via the comparison of tasks refers to the specific form of processing resulted by retrieval efforts. Strategic recollection is the type of strategies to recollect studied items for the retrieval success of targets. Using a “directed forgetting” paradigm combined with a memory exclusion task, our investigation of strategic retrieval in directed forgetting assisted to explore how retrieval inhibition played a role on directed forgetting effects. When TBF items were targeted, retrieval orientation showed more positive ERPs to new items, indicating that TBF items demanded more retrieval efforts. The results of strategic recollection indicated that: (a) when TBR items were retrieval targets, late parietal old/new effects were only evoked by TBR items but not TBF items, indicating the retrieval inhibition of TBF items; (b) when TBF items were retrieval targets, the late parietal old/new effect were evoked by both TBR items and TBF items, indicating that strategic retrieval could overcome retrieval inhibition of TBF items. These findings suggested the modulation of strategic retrieval on retrieval inhibition of directed forgetting, supporting that directed forgetting effects were not only caused by selective rehearsal, but also retrieval inhibition.

Direct electrophysiological evidence for the maintenance of retrieval orientations and the role of cognitive control

“…Retrieval orientations have been linked to the cognitive control of episodic retrieval via the presence of stimulus-locked orientation effects in conjunction with neural evidence of ‘strategic retrieval’ ( Herron and Rugg, 2003 , Dzulkifli and Wilding, 2005 , Dzulkiflil et al., 2006 , Morcom and Rugg, 2012 , Rosburg et al., 2013 , Mao et al., 2017 ). Strategic retrieval refers to the controlled recollection of task-relevant contextual details alongside a reduction in the recollection of less-relevant memories.…”

“…Neural evidence for strategic retrieval takes the form of significantly larger neural correlates of recollection for targets than for nontargets, these being the ‘left parietal old/new effect’ in ERP studies (i.e. a positive-going shift at left parietal electrode sites for recollected items; ( Herron and Rugg, 2003 , Dzulkifli and Wilding, 2005 , Rosburg et al., 2013 , Mao et al., 2017 )) and left angular gyrus activation in the fMRI parallel ( Morcom and Rugg, 2012 ). The fact that all of these studies reported neural correlates of strategic retrieval in conjunction with stimulus-locked neural correlates of retrieval orientation indicates that strategic retrieval may be enabled by the maintenance of target-centric retrieval orientations which facilitate the recollection of target memories at the expense of nontarget memories.…”

Cognitive control depletion reduces pre-stimulus and recollection-related measures of strategic retrieval

“…Second, pre-stimulus ERPs also differ according to target designation 11, 27 . Third, ERP measures of recollection associated with nontargets are significantly smaller than those associated with targets, this being the parietal old/new effect in ERP studies 12, 22, 35, 36 and activation in angular gyrus in their fMRI counterpart 18 . This third aspect is termed ‘strategic retrieval’ and there was evidence for this in control participants here, with target ERPs eliciting greater positivity than both nontargets and new items .…”

“…‘Strategic retrieval’ refers to the prioritised retrieval of goal-specific contextual information, and manifests as larger recollection effects for targets than for nontargets. The ERP correlate of recollection is enhanced positivity at parietal electrode sites between 500–800ms, and this is often significantly larger for targets than for nontargets 12, 22, 35, 36 . Elward et al 33 found that participants with high working memory capacity (measured using O-span performance) showed ERP evidence of strategic retrieval, but that this was eliminated following the Stroop task.…”

Can self-referential information improve directed forgetting? Evidence from a multinomial processing tree model

“…The present study does not involve a discussion of emotions and personality traits. Because Mao et al (2017) found that participants also experienced DF of specific nouns under a self-referential condition [8, 24], we chose specific nouns that were related closely to daily life as materials.…”