An Electrophysiological Dissociation of Encoding vs. Maintenance Failures in Visual-Spatial Working Memory

Abstract

Working memory (WM) performance varies substantially among individuals but the precise contribution of different WM component processes to these functional limits remains unclear. By analyzing different types of responses in a spatial WM task, we recently demonstrated a functional dissociation between confident and not-confident errors reflecting failures of WM encoding and maintenance, respectively. Here, we use event-related brain potentials to further explore this dissociation. Healthy participants performed a delayed orientation-discrimination task and rated their response confidence for each trial. The encoding-related N2pc component was significantly reduced for confident errors compared to confident correct responses, which is indicative of an encoding failure. In contrast, the maintenance-related contra-lateral delay activity was similar for these response types indicating that in confident error trials, WM representations-potentially the wrong ones-were maintained accurately and with stability throughout the delay interval. However, contra-lateral delay activity measured during the early part of the delay period was decreased for not-confident errors, potentially reflecting compromised maintenance processes. These electrophysiological findings contribute to a refined understanding of the encoding and maintenance processes that contribute to limitations in WM performance and capacity.

Tracking attentional states: Assessing the relationship between sustained and selective focused attention in visual working memory

“…Confidence ratings have been more broadly used in VWM research. Introspective confidence judgements track memory accuracy when recall is measured on a continuous scale (Mitchell et al, 2018;Peters et al, 2019;Rademaker et al, 2012), as well as in change detection (Berryhill et al, 2012;Mayer et al, 2020;Sahar et al, 2020). This indicates that trial-to-trial fluctuations in VWM for continuous features are accessible to introspection similar to memory for discrete colors (Adam & Vogel, 2017;Arnicane et al, 2021;Peters et al, 2019).…”

“…Introspection on attentional states is assumed to reflect knowledge about the state of preparedness to perform the task or of task focus more generally (Adam & Vogel, 2017;Unsworth & McMillan, 2014a, 2014b. Confidence ratings, conversely, request participants to predict or evaluate their performance in the memory test, which is assumed to be guided by the precision of the relevant memory representations (Mayer et al, 2020;Peters et al, 2019;Rademaker et al, 2012;Samaha & Postle, 2017;van den Berg et al, 2017;Vandenbroucke et al, 2014). Both attention and confidence reports have been found to relate to performance in VWM tasks.…”

“…Future studies are needed to assess whether attention fluctuations contribute to maintenance across longer retention intervals, which can be particularly relevant for testing proposals that VWM maintenance involves sustained visual attention to representations (Chun, 2011). Time-sensitive measures such as EEG could also be useful to disentangle the time period in which fluctuations occurred (Killebrew et al, 2018;Mayer et al, 2020), as reflected in the self-reports of low or high-levels of attention.…”

Working memory and sensory memory in subclinical high schizotypy: An avenue for understanding schizophrenia?

“…Additional effects likely arise from gamma‐band oscillatory activity during WM tasks that fail to increase with increased WM load in those with schizophrenia (Basar‐Eroglu et al, 2007; Cho et al, 2006). A second biomarker of encoding‐related WM deficit is the N2pc, which is also reduced in those with schizophrenia (Mayer et al, 2020). Broadly atypical frontal lobe activations in at‐risk youth (van Gool et al, 2022) and connectivity patterns are known across schizophrenia spectrum disorders (Briend et al, 2020; Schmidt et al, 2014) and at‐risk samples (Schutte et al, 2021).…”

Working Memory and Sensory Memory in Subclinical High Schizotypy: An Avenue for Understanding Schizophrenia?

“…Additional effects likely arise from gamma-band oscillatory activity during WM tasks that fails to increase with increased WM load in those with schizophrenia (Basar-Eroglu et al, 2007;Cho et al, 2006). A second biomarker of encoding-related WM deficit is the N2pc, which is also reduced in those with schizophrenia (Mayer et al, 2020). Broadly atypical frontal lobe activations in at risk youth (van Gool et al, 2022) and connectivity patterns are known across schizophrenia spectrum disorders (Briend et al, 2020;Schmidt et al, 2014), and at risk samples (Schutte et al, 2021).…”