Distinct Electrophysiological Signatures of Intentional and Unintentional Mind-Wandering Revealed by Low-Frequency EEG Markers

Martel, Adrien; Bruno, Nicolas; Dockree, Paul; Robertson, Ian; Sitt, Jacobo; Valero-Cabre, Antoni · 2023 · Crossref

DOI: 10.21203/rs.3.rs-2946669/v1

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Summary

This study investigates the distinct electrophysiological signatures of intentional and unintentional mind-wandering, addressing the need to differentiate these states due to their divergent clinical and functional outcomes. While mind-wandering is often treated as a uniform phenomenon, unintentional task-unrelated thought (uTUT) is linked to adverse effects such as psychopathologies, whereas intentional task-unrelated thought (iTUT) can support creativity and planning. The research aims to identify specific EEG markers that distinguish on-task states from off-task states, and further separate iTUT from uTUT, challenging the prevailing view that alpha band activity is a generic marker for all mind-wandering. The researchers employed a Sustained Attention to Response Task (SART) with 26 participants, collecting EEG data alongside multidimensional thought probes. Participants reported their attentional states via both probe-caught and self-caught methods, categorizing thoughts as on-task, distracted, iTUT, or uTUT. The analysis focused on 54 predefined EEG markers derived from recordings immediately preceding these reports, encompassing event-related potentials, spectral power, connectivity, and permutation entropy. Univariate and multivariate pattern analyses, including Extra Trees classifiers, were used to assess the discriminative power of these features across different attentional states. The findings revealed distinct neural signatures for each state. Normalized theta power was the most discriminative marker for distinguishing on-task from off-task states, with higher theta power associated with on-task engagement. Crucially, alpha band activity did not differentiate on-task from off-task states generally but significantly distinguished iTUT from uTUT. Specifically, iTUT was characterized by increased theta permutation entropy and greater alpha power compared to uTUT. Conversely, uTUT was associated with increased normalized delta power. Multivariate analysis confirmed that these patterns allowed for above-chance classification of intentional versus unintentional mind-wandering, with theta permutation entropy identified as the most important feature. These results challenge the assumption that increased alpha activity is a universal marker of mind-wandering, suggesting instead that it reflects the top-down inhibition of sensory input required for intentional internal focus. The study concludes that intentional and unintentional mind-wandering involve separate cortical architectures and unique brain activity patterns. This distinction supports the development of reliable, real-time EEG-based detection systems for mind-wandering, which could facilitate objective monitoring in clinical settings, such as for ADHD, and practical applications like enhancing focus in educational or occupational environments.

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Topics

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• mind wandering
• neuro workload indices