Review Article | Published:

Mind-wandering as spontaneous thought: a dynamic framework

Nature Reviews Neuroscience volume 17, pages 718731 (2016) | Download Citation

Abstract

Most research on mind-wandering has characterized it as a mental state with contents that are task unrelated or stimulus independent. However, the dynamics of mind-wandering — how mental states change over time — have remained largely neglected. Here, we introduce a dynamic framework for understanding mind-wandering and its relationship to the recruitment of large-scale brain networks. We propose that mind-wandering is best understood as a member of a family of spontaneous-thought phenomena that also includes creative thought and dreaming. This dynamic framework can shed new light on mental disorders that are marked by alterations in spontaneous thought, including depression, anxiety and attention deficit hyperactivity disorder.

Key points

  • In the past 15 years, mind-wandering has become a prominent topic in cognitive neuroscience and psychology. Whereas mind-wandering has come to be predominantly defined as task-unrelated and/or stimulus-unrelated thought, we argue that this content-based definition fails to capture the defining quality of mind-wandering: the relatively free and spontaneous arising of mental states as the mind wanders.

  • We define spontaneous thought as a mental state, or a sequence of mental states, that arises relatively freely due to an absence of strong constraints on the contents of each state and on the transitions from one mental state to another. We propose that there are two general ways in which the content of mental states, and the transitions between them, can be constrained.

  • Deliberate and automatic constraints serve to limit the contents of thought and how these contents change over time. Deliberate constraints are implemented through cognitive control, whereas automatic constraints can be considered as a family of mechanisms that operate outside of cognitive control, including sensory or affective salience.

  • Within our framework, mind-wandering can be defined as a special case of spontaneous thought that tends to be more deliberately constrained than dreaming, but less deliberately constrained than creative thinking and goal-directed thought. In addition, mind-wandering can be clearly distinguished from rumination and other types of thought that are marked by a high degree of automatic constraints, such as obsessive thought.

  • In general, deliberate constraints are minimal during dreaming, tend to increase somewhat during mind-wandering, increase further during creative thinking and are strongest during goal-directed thought. There is a range of low-to-medium level of automatic constraints that can occur during dreaming, mind-wandering and creative thinking, but thought ceases to be spontaneous at the strongest levels of automatic constraint, such as during rumination or obsessive thought.

  • We propose a neural model of the interactions among sources of variability, automatic constraints and deliberate constraints on thought: the default network (DN) subsystem centred around the medial temporal lobe (MTL) (DNMTL) and sensorimotor areas can act as sources of variability; the salience networks, the dorsal attention network (DAN) and the core DN subsystem (DNCORE) can exert automatic constraints on the output of the DNMTL and sensorimotor areas, thus limiting the variability of thought; and the frontoparietal control network can exert deliberate constraints on thought by flexibly coupling with the DNCORE, the DAN or the salience networks, thus reinforcing or reducing the automatic constraints being exerted by the DNCORE, the DAN or the salience networks.

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Acknowledgements

The authors are grateful to R. Buckner, P. Carruthers, M. Cuddy-Keane, M. Dixon, S. Fazelpour, D. Stan, E. Thompson, R. Todd and the anonymous reviewers for their thoughtful feedback on earlier versions of this paper, and to A. Herrera-Bennett for help with the figure preparation. K.C. was supported by grants from the Natural Sciences and Engineering Research Council (NSERC) (RGPIN 327317–11) and the Canadian Institutes of Health Research (CIHR) (MOP-115197). Z.C.I. was supported by a Social Sciences and Humanities Research Council of Canada (SSHRC) postdoctoral fellowship, the Balzan Styles of Reasoning Project and a Templeton Integrated Philosophy and Self Control grant. K.C.R.F. was supported by a Vanier Canada Graduate Scholarship. R.N.S. was supported by an Alzheimer's Association grant (NIRG-14-320049). J.R.A.-H. was supported by a Templeton Science of Prospection grant.

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Affiliations

  1. Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, V6T 1Z4, Canada.

    • Kalina Christoff
    •  & Kieran C. R. Fox
  2. Centre for Brain Health, University of British Columbia, 2211 Wesbrook Mall, Vancouver, British Columbia, V6T 2B5, Canada.

    • Kalina Christoff
  3. Departments of Philosophy and Psychology, University of California, Berkeley, California 94720, USA.

    • Zachary C. Irving
  4. Laboratory of Brain and Cognition, Department of Human Development, Cornell University.

    • R. Nathan Spreng
  5. Human Neuroscience Institute, Cornell University, Ithaca, New York 14853, USA.

    • R. Nathan Spreng
  6. Institute of Cognitive Science, University of Colorado Boulder, UCB 594, Boulder, Colorado 80309–0594, USA.

    • Jessica R. Andrews-Hanna

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Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Kalina Christoff.

Glossary

Thought

A mental state, or a sequence of mental states, including the transitions that lead to each state.

Mental state

A transient cognitive or emotional state of the organism that can be described in terms of its contents (what the state is 'about') and the relation that the subject bears to the contents (for example, perceiving, believing, fearing, imagining or remembering).

Task-unrelated thoughts

Thoughts with contents that are unrelated to what the person having those thoughts is currently doing.

Daydreaming

Thinking that is characteristically fanciful (that is, divorced from physical or social reality); it can either be spontaneous, as in fanciful mind-wandering, or constrained, as during deliberately fantasizing about a topic.

Stimulus-independent thought

A thought with contents that are unrelated to the current external perceptual environment.

Cognitive control

A deliberate guidance of current thoughts, perceptions or actions, which is imposed in a goal-directed manner by currently active top-down executive processes.

Affective salience

The emotional significance of percepts, thoughts or other elements of mental experience, which can draw and sustain attention through mechanisms outside of cognitive control.

Sensory salience

Features of current perceptual experience, such as high perceptual contrast, which can draw and sustain attention through mechanisms outside of cognitive control.

Mentalizing

The process of spontaneously or deliberately inferring one's own or other agents' mental states.

Constructive mental simulations

Flexible combinations of distinct elements of prior experiences, constructed in the process of imagining a novel (often future-oriented) event.

Lucid dreaming

A type of dreaming during which the dreamer is aware that he or she is currently dreaming and, in some cases, can have deliberate control over dream content and progression.

Creativity

The ability to produce ideas that are both novel (that is, original and unique) and useful (that is, appropriate and meaningful).

Experience sampling

A method in which participants are probed at random intervals and asked to report on aspects of their subjective experience immediately before the probe.

Content-based dimensions of thought

Different ways of categorizing a thought based on its contents, including stimulus dependence (whether the thought is about stimuli that one is currently perceiving), task relatedness (whether the thought is about the current task), modality (visual, auditory, and so on), valence (whether the thought is negative, neutral or positive) or temporal orientation (whether the thought is about the past, present or future).

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DOI

https://doi.org/10.1038/nrn.2016.113

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