Session 3: Mind Wandering & Meta-attention (Theories of mind-wandering)

Smallwood and Schooler (2006)* and McVay and Kane (2010)** proposed two competing theories to explain mind wandering: an “executive function” theory and an “executive failure” theory. The “executive function” theory posits that mind wandering requires executive control and uses the same cognitive resources needed to complete a conscious task (Smallwood & Schooler, 2006). Thus, mind wandering should involve the same brain regions associated with executive control and should increase with ease and practice of the task the person should be focusing on because both ease and practice free up cognitive resources for mind wandering (Smallwood & Schooler, 2006; Schooler et al., 2011***). By contrast, the executive failure theory explains mind wandering as a failure of executive control over off-task thoughts that are generated automatically (McVay & Kane, 2010). Under this theory, mind wandering should involve different brain regions than executive control, particularly the default network that is responsible for self-projection even in the absence of external cues, and mind wandering should increase with sleepiness, inebriation, lower working memory capacity, and disorders like ADHD that involve executive function deficits (McVay & Kane, 2010). In general, the executive failure theory seems to better explain the available evidence on individual differences and compromised states, but it does not satisfactorily explain one set of neuroimaging data that appears to support the executive function theory.

Both theories provide explanations for why mind wandering increases when people are doing easier tasks or tasks they have practiced extensively. The executive function theory is possibly more elegant here: it predicts that tasks requiring fewer executive resources, especially working memory resources, free up more resources for mind wandering (Smallwood & Schooler, 2006). Thus, easier tasks and well-practiced tasks that a person does relatively automatically should be associated with more mind wandering. But the executive failure theory can also explain this phenomenon. McVay and Kane (2010) explained harder tasks as requiring a more concrete level of construal to complete and easier or more practiced tasks as needing only a more abstract level of construal. More concrete levels of construal require more executive control processes to match to the current situation, and the increased executive control resources also tend to block off-task thoughts (McVay & Kane, 2010).

Similarly, both theories can explain findings that mind wandering interferes with performance on the task at hand. Smallwood and Schooler (2006) explain the interference as a diversion of executive resources away from the task. McVay and Kane (2010) do not explain the interference directly, but it seems plausible that distraction, even if the distracting thoughts did not use the same cognitive resources as the task, would degrade performance.

But the executive failure theory better accounts for individual differences in mind wandering tendencies than does the executive function theory. As McVay and Kane (2010) pointed out, if mind wandering uses executive resources then people with fewer resources to spare—those with low working memory capacity or disorders like ADHD or merely people who are tired or drunk—should mind wander less than those with more resources to spare. Instead, these individuals have been shown to mind wander more (McVay & Kane, 2010; Schooler et al., 2011). Schooler et al. (2011) discussed drinking and nicotine craving as increasing mind wandering while decreasing meta-awareness of mind wandering, but they did not seem to reconcile the increase in mind wandering with the executive function theory.

However, one neuroimaging study tends to support the executive function theory of mind wandering and seems inadequately explained by the executive failure theory. Mind wandering episodes have been found to be associated with activity in regions of the brain (certain areas of the prefrontal cortex, PFC, and anterior cingulate cortex, ACC) that are generally associated with executive control (McVay & Kane, 2010; Schooler et al., 2011). Mind wandering without meta-awareness (i.e., when the person is unaware that he or she is mind wandering) also is associated with stronger activity in those regions than mind wandering with meta-awareness is (McVay & Kane, 2010). McVay and Kane (2010) suggested that this activation reflects the effort of refocusing on the task at hand and that conscious awareness of mind wandering is not necessary for the refocusing to happen. But that seems to suggest a time lag between the onset of mind wandering and PFC and ACC activation, and McVay and Kane (2010) did not suggest that any such time lag occurred. Their suggestion that refocusing may require more control activity during mind wandering without meta-awareness than during mind wandering with meta-awareness (McVay & Kane, 2010) also begs the question of why that would be the case. Thus, without temporal data or a theoretical reason for why refocusing attention requires more control resources in mind wandering without meta-awareness, activation of the PFC and ACC during mind wandering seems to support the executive function theory and contradict the executive failure theory of mind wandering.

As a side note, Schooler et al. (2011) suggested that reductions in neural responses to task stimuli during mind wandering indicate that “reduction in task focus due to mind wandering arises from the internal focus necessary to maintain an internal train of thought, rather than a process of distraction” (p. 320). To a novice, this is not apparent at all—why could a process of distraction not produce the same response reductions?

* Smallwood, J. & Schooler, J. W. (2006). The restless mind. Psychological Bulletin, 132, 946-958.

** McVay, J. C. & Kane, M. J. (2010). Does mind wandering reflect executive function or executive failure? Comment on Smallwood and Schooler (2006) and Watkins (2008). Psychological Bulletin, 136, 188-197.

*** Schooler, J. W., Smallwood, J., Christoff, K., Handy, T. C., Reichle, E. D., & Sayette, M. A. (2011). Meta-awareness, perceptual decoupling and the wandering mind. Trends in Cognitive Sciences, 15, 319-326.