Distinct electrophysiological signatures of task-unrelated and dynamic thoughts

Julia W.Y. Kam, Zachary C. Irving, Caitlin Mills, Shawn Patel, Alison Gopnik, Robert T. Knight

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Humans spend much of their lives engaging with their internal train of thoughts. Traditionally, research focused on whether or not these thoughts are related to ongoing tasks, and has identified reliable and distinct behavioral and neural correlates of task-unrelated and task-related thought. A recent theoretical framework highlighted a different aspect of thinking—how it dynamically moves between topics. However, the neural correlates of such thought dynamics are unknown. The current study aimed to determine the electrophysiological signatures of these dynamics by recording electroencephalogram (EEG) while participants performed an attention task and periodically answered thought-sampling questions about whether their thoughts were 1) task-unrelated, 2) freely moving, 3) deliberately constrained, and 4) automatically constrained. We examined three EEG measures across different time windows as a function of each thought type: stimulus-evoked P3 event-related potentials and non–stimulus-evoked alpha power and variability. Parietal P3 was larger for task-related relative to task-unrelated thoughts, whereas frontal P3 was increased for deliberately constrained compared with unconstrained thoughts. Frontal electrodes showed enhanced alpha power for freely moving thoughts relative to non-freely moving thoughts. Alpha-power variability was increased for task-unrelated, freely moving, and unconstrained thoughts. Our findings indicate distinct electrophysiological patterns associated with task-unrelated and dynamic thoughts, suggesting these neural measures capture the heterogeneity of our ongoing thoughts.

Original languageEnglish (US)
Article numbere2011796118
JournalProceedings of the National Academy of Sciences of the United States of America
Volume118
Issue number4
DOIs
StatePublished - Jan 26 2021
Externally publishedYes

Bibliographical note

Funding Information:
Many thanks to our participants for their time and effort in our study. We also appreciate useful feedback from Kalina Christoff, Alan Shen, and Chandra Sripada during study conceptualization. Z.C.I., C.M., and J.W.Y.K. were supported by the Templeton Foundation. J.W.Y.K. was also supported by the James McDonnell Foundation and the Natural Sciences and Engineering Research Council of Canada. A.G. was supported by DARPA Machine Common Sense, the John Templeton Foundation, and the Bezos Foundation. R.T.K. was supported by National Institute of Neurological Disorders and Stroke Grant NS21135.

Publisher Copyright:
© 2021 National Academy of Sciences. All rights reserved.

Keywords

  • Constrained thoughts
  • EEG
  • Freely moving thoughts
  • Mind wandering
  • Task-unrelated thoughts

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