ERP Correlates of Encoding Success and Encoding Selectivity in Attention Switching

Abstract

Long-term memory encoding depends critically on effective processing of incoming information. The degree to which participants engage in effective encoding can be indexed in electroencephalographic (EEG) data by studying event-related potential (ERP) subsequent memory effects. The current study investigated ERP correlates of memory success operationalised with two different measures—memory selectivity and global memory—to assess whether previously observed ERP subsequent memory effects reflect focused encoding of task-relevant information (memory selectivity), general encoding success (global memory), or both. Building on previous work, the present study combined an attention switching paradigm—in which participants were presented with compound object-word stimuli and switched between attending to the object or the word across trials—with a later recognition memory test for those stimuli, while recording their EEG. Our results provided clear evidence that subsequent memory effects resulted from selective attentional focusing and effective top-down control (memory selectivity) in contrast to more general encoding success effects (global memory). Further analyses addressed the question of whether successful encoding depended on similar control mechanisms to those involved in attention switching. Interestingly, differences in the ERP correlates of attention switching and successful encoding, particularly during the poststimulus period, indicated that variability in encoding success occurred independently of prestimulus demands for top-down cognitive control. These results suggest that while effects of selective attention and selective encoding co-occur behaviourally their ERP correlates are at least partly dissociable.

Prediction errors indexed by the P3 track the updating of complex long-term memory schemas

“…Thus, it is likely that participants accepted a certain degree of noise in the consistent categories (based on their experience of the same level of noise on day 1), but in the inconsistent conditions, they were able to recognise that the change in locations could not only be explained by noise, and thus these new locations elicited an increased surprise signal, evident in a larger P3a. This finding of increased P3a amplitude is consistent with the idea that frontal areas are recruited in the face of novel, unexpected stimuli (Soltani & Knight, 2000), that attract attention, which again might aid later memory (Richter & Yeung, 2016). Importantly, in the current study the source of this novelty or surprise signal is solely based on a consolidated memory schema, and not on recently encountered information.…”

“…The EEG analysis focused on two clusters of interest: the fronto-central and centro-parietal electrodes. These locations had been shown to display beliefupdating effects (Bennett et al, 2015;Jepma et al, 2018Jepma et al, , 2016Kolossa et al, 2015), in previous studies, and have displayed differential involvement in subsequent memory effects (Richter & Yeung, 2016). In a first step, I tested the prediction that the P3 should be more pronounced in the inconsistent than the consistent condition during day 2 learning.…”

“…However, behavioural evidence suggests that PE-based learning also works on longer time-scales (Greve et al, 2019;Pine et al, 2018), and for some types of memory (e.g., semantic knowledge) it has been shown to rely on similar mid-brain regions that are also thought to underlie the updating of more short lived beliefs (Garrison, Erdeniz, & Done, 2013;Pine et al, 2018). Moreover, the P3a and the P3b have been linked to better encoding such that larger amplitudes of either potential are associated with better memory in a subsequent test (Azizian & Polich, 2007;Knight & Scabini, 1998;Richter & Yeung, 2016). Therefore, the P300 might also index updating in long-term memory.…”

Environmental rhythms orchestrate neural activity at multiple stages of processing during memory encoding: Evidence from event-related potentials

“…For these later N2/P3 attentional components, analysis focused on more frontocentral electrodes (Cz, Fz) given the topography of post-perceptual attentional effects previously observed in the literature [32,36,46,50]. Mean amplitudes of the frontal slow wave were calculated across a cluster of frontal electrodes (Fz, FP1, FP2) during a time window ranging from 450-750ms based on the timing and topography of prior subsequent memory effects observed in the literature [47][48][49][50][51][52][53][54].…”

“…Electrophysiological studies have identified a more sustained frontal slow wave (FSW) occurring later in time (>500ms after stimulus presentation) that predicts whether or not a stimulus will be later remembered or forgotten (subsequent memory) [45][46][47]. This ERP subsequent memory effect is most commonly observed over frontal electrodes in task contexts that strengthen memory encoding (e.g., deep vs. shallow processing, semantic vs. non-semantic classification) and has been linked to more elaborative, frontally-mediated cognitive processing that leads to the formation of a more durable memory trace [47][48][49][50][51][52][53][54]. Although there has been little research into the effects of temporal orienting on electrophysiological responses occurring during this later time window, modulations of this more sustained frontal response may be particularly relevant to effective memory encoding.…”