If you’re going to get any sort of science done, an experiment needs a control group: the unaffected, possibly placebo-ed population that didn’t take part in whatever intervention it is you’re trying to study. Back in the earlier days of cognitive neuroscience, the control condition was intuitive enough: Just let the person in the brain scanner lie in repose, awake yet quiet, contemplating the tube they’re inside of. But in 1997, 2001, and beyond, studies kept coming out saying that it wasn’t much of a control at all. When the brain is “at rest,” it’s doing anything but resting.
When you don’t give its human anything to do, brain areas related to processing emotions, recalling memory, and thinking about what’s to come become quietly active. These self-referential streams of thought are so pervasive that in a formative paper Marcus Raichle, a Washington University neurologist who helped found the field, declared it to be the “the default mode of brain function,” and the constellation of brain areas that carry it out are the default mode network, or DMN. Because when given nothing else to do, the brain defaults to thinking about the person it’s embedded in. Since then, the DMN has been implicated in everything from depression to creativity. People who daydream more tend to have a more active DMN; relatedly, dreaming itself appears to be an amplified version of mind-wandering.
In Buddhist traditions, this chattering described by neuroscientists as the default mode is a dragon to be tamed, if not slain. Chögyam Trungpa, who was instrumental in bringing Tibetan Buddhism to the U.S., said the meditation practice is “necessary generally because our thinking pattern, our conceptualized way of conducting our life in the world, is either too manipulative, imposing itself upon the world, or else runs completely wild and uncontrolled,” he wrote in Cutting Through Spiritual Materialism. “Therefore, our meditation practice must begin with ego’s outermost layer, the discursive thoughts which continually run through our minds, our mental gossip.”
In his book Mindfulness for Beginners: Reclaiming the Present Moment ― and Your Life, Jon Kabat-Zinn, the founder of mindfulness-based stress reduction, argues that this idle narration, this “selfing,” is something that needs to be reined in order to have a balanced mental life. When the DMN “predominates, especially out of unawareness, it can very much limit our understanding of ourselves and of what might be possible,” he argues. The crux of the Buddhist argument is that if you don’t establish some relationship with your DMN, some mindfulness of its activity, you’ll be yanked around by the swirling eddies of emotion, reaction, and rumination. But what do brain sciences say?
Whether or not your default activity is helpful or harmful depends on where your mind automatically tends to go, says Scott Barry Kaufman, the scientific director at the Imagination Institute at the University of Pennsylvania. In the same way that your tongue defaults to probing a cut on the roof of your mouth, the brain is attracted to unresolved issues. “People differ drastically regarding if their default mode network content is creative or ruminative,” he says.
In a way, the DMN is like a scout, ranging about for prospective futures. To Kaufman, the default mode has a “prospective bias”: It’s seeking out big-picture strategies for what could be. Depending on the person, their history, and their biological dispositions, that prospection could tilt toward worrying or hoping. As psychologists have contended for decades, daydreaming itself has at least three different flavors: positive constructive daydreaming, which has lots of playful, wishful imagery and plan-making thoughts; guilty-dysphoric daydreaming, which has lots of anguish and obsessive fantasies; and poor attentional control, where it’s hard to concentrate on anything. “Prospection can lead to suffering if it hinders executive attention, the ability to have awe, attention to the present moment,” he says, emphasizing that, as with so many others ways that our minds get into trouble, the problem is rigidity; research indicates that a disturbed DMN is a mechanism in depression. “Our greatest source of suffering isn’t the default mode,” Kaufman says, “but when we get stuck in the default mode.”
Indeed, the peripatetic nature of the DMN can be harnessed for creative thinking. In a 2015 Scientific Reports paper that Kaufman co-authored, 25 participants were asked to do creative thinking tasks, including the standard measure of divergent thinking, asking how many uses you can come up with for a brick (spoiler alert: doorstop and weapon are two go-to options). At the start of the task, the DMN coupled with the salience network, which selects which stimuli to attend to, and toward the end of the task, it coupled with the executive network, which is responsible for the control of attention and working memory — results that suggest that producing creative ideas requires a combination of focusing internal attention and controlling spontaneous thinking. “The DMN contributes to the (more or less) spontaneous generation of (potentially useful) ideas,” co-author and Harvard postdoc Roger Beaty told Science of Us via email.
It underscores the fact that not all minds that wander are lost. University of British Columbia philosopher Evan Thompson, author of Waking, Dreaming, Being: Self and Consciousness in Neuroscience, Meditation, and Philosophy, says the DMN’s mental meanderings are “the baseline state of you as a cognitive system.” It’s tremendously pragmatic: being able to remember the past, plan for the future, and happen upon creative insights are all essential tools for navigating life. While he was hesitant to mix the word “suffering,” which is so loaded in ancient Asian religious traditions, with the “default mode,” which is of a contemporary neural vintage, the two connect in the way that suffering arises when people concretize the fleeting swirls of thought, especially around conceptions of self. Still, he says, there’s “particular kind of stickiness” that can come when DMN activity grows overly self-centered.
Default-mode content involves an image of self, one that’s easy to become attached to. These self-conceptions are “affectively charged,” he says; they carry lots of emotional weight. “We constantly think that it’s not just another thought, that [the image of self] is something real, not just an mental image.”
He compared it with a strawberry and thoughts of a strawberry. If you’re a particularly good imaginer, you might start salivating at the image of a ripe, inviting strawberry. Still, it’s just a mental image; not an actual strawberry. The “selfing” conjured up by the DMN is a lot like that: images of who you think you are, but not who you actually are. While you wouldn’t take a mental image of a strawberry to be an appropriate filling to a real-world shortcake, it’s easy to take your mental images of you to be your real-world self.
“The self isn’t one thing, it’s an evolving construct of many different processes,” Thompson says.“Contemplative traditions like Buddhism and yoga would say that habitually investing in the image of the self more reality than it actually has is a source of great difficulty. When we take it to be real when it isn’t, according to these traditions, then that causes suffering.” He mentioned that in cognitive behavioral therapy, that process of divesting realness from your mental chatter is called “decentering,” or thinking less that your thoughts are the truth about what’s happening and viewing them as an observer. The therapeutic interventions offered by psilocybin and LSD — which, at least in one trial, helped longtime smokers quit at a rate three times that of the best pharma drugs — seem to have a similar, though more sudden, effect.
At a phenomenological, subjective, what-it’s-like level, the trouble or lack thereof that your DMN gets into seems to depend on how automatic (or de-automatized) your patterns of thought are. Lots of our trains of thought, as suggest by the term train, speed along as if carried by a locomotive, one after another, carried by mental-emotional momentum. If you’re more biologically sensitive to perceived threats, it’s likely that it’s a direct line to rumination, or negatively, recursively reflecting on how you’re bad at your job, rock-climbing, dealing with your family on holidays, or whatever the task is. Though by that point the amygdala, so present in neuroticism, will probably be involved, too.
The key is what brain science people call “cognitive flexibility”: being able to more freely choose your mental habits, and have greater agency in your cognitive phenomena. CBT and even hypnosis are options for taming an unruly DMN, as is the fashionable yet ancient practice of meditation. Study after study indicates that meditation reduces activity in the DMN. Judson Brewer, psychiatrist and director of research at the UMass Medical School Center for Mindfulness founded by Kabat-Zinn, has found that extended meditation practice reforms the DMN, so that the default mode itself shifts: The resting state of the brain becomes more like the meditative state, producing “a more present-centered default mode.” So maybe that’s what all that advice to live in the present moment is getting at: If you can invest more attention in the sensory world than in your narrative overlaying it, you might identify the former, rather than the latter, to be what’s true.