Some wander more than others, but human ones wander a lot. A much-cited estimate, due to Killingsworth and Gilbert (2010), has it that the awake human mind spends from a third to half its time wandering. That’s a big range, a rough estimate, and there are good reasons to be suspicious of it (see Seli et al. 2018).
The actual number will likely depend a bit upon the nature of mind wandering, a bit upon whether we have the right measure to produce such an estimate, and of course a bit on individual variability.
Estimates aside, though, introspection reports that the mind wanders surprisingly often. My question here is this.
Why does it happen?
Sub-questions include the following. What drives the mind to wander? Does anything drive it to wander? Is the transition from focused thought to meandering thought random? Is it a failure of control, or is there some dark purpose behind these mental movements?
In the next section, I set the table by discussing a few interesting features of mind wandering, as well as a few recent proposals about its etiology, and its function. It is easy to conflate these two,
since if mind wandering has a function its etiology may very well help illuminate it, but the questions are distinct. Here, I am more interested in why mind wandering happens—about its etiology. It turns out, though,
that on my proposal mind wandering happens for good functional reasons. I develop this proposal, which I call the cognitive control proposal, in Cognitive control and Why the mind wanders sections.
In Explanations section, I discuss some explanations this proposal makes possible. In Predictions section, I discuss some predictions that could confirm or disconfirm the proposal. In Philosophical implications section, I discuss implications for a philosophical account of the nature of mind wandering.
