Where Will Happens in the Brain

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Philosophers have been arguing about the nature of will for at least 2,000 years. It’s at the core of blockbuster social-psychology findings, from delayed gratification to ego depletion to grit. But it’s only recently, thanks to the tools of brain imaging, that the act of willing is starting to be captured at a mechanistic level.

A primary example is “cognitive control,” or how the brain selects goal-serving behavior from competing processes like so many unruly third-graders with their hands in the air. It’s the rare neuroscience finding that’s immediately applicable to everyday life: By knowing the way the brain is disposed to behaving or misbehaving in accordance to your goals, it’s easier to get the results you’re looking for, whether it’s avoiding the temptation of chocolate cookies or the pull of darkly ruminative thoughts.

Jonathan Cohen, who runs a neuroscience lab dedicated to cognitive control at Princeton, says that it underlies just about every other flavor of cognition that’s thought to “make us human,” whether it’s language, problem solving, planning, or reasoning.

“If I ask you not to scratch the mosquito bite that you have, you could comply with my request, and that’s remarkable,” he says. Every other species — ape, dog, cat, lizard — will automatically indulge in the scratching of the itch. (Why else would a pup need a post-surgery cone?) It’s plausible that a rat or monkey could be taught not to scratch an itch, he says, but that would probably take thousands of trials. But any psychologically and physically able human has the capacity to do so. “It’s a hardwired reflex that is almost certainly coded genetically,” he says. “But with three words — don’t scratch it — you can override those millions of years of evolution. That’s cognitive control.”

As Cohen detailed in a 2014 review in Cognitive Science, the key structure in the brain responsible for cognitive control is the prefrontal cortex (PFC). It’s a matter of maintaining a pattern of brain activity — technically, a “representation” — that allows you to pursue a conscious goal rather than an automatic behavior. He’s careful to note that the PFC doesn’t suppress activity elsewhere in the brain (“It’s not playing Whac-A-Mole”), but rather it’s somewhere between air-traffic controller, conductor, and DJ.

Back to that mosquito bite that begs to be scratched. There’s a quiet storm of electrical signals in your brain crying out for sweet relief. But you have the uniquely human capacity to not scratch it. The PFC does this in the same way an orchestra conductor might bring up the string section over the woodwinds or a DJ might turn up the volume of one track over another. “You can almost intuit on what it would feel like,” he says. “I’ll put my hand over here, and actively engage the counter muscles to the ones that would do the scratching.” Not coincidentally, this is precisely the sort of behavior kids displayed in Walter Mischel’s famous marshmallow experiments, where children would mime being asleep or start talking to themselves like Charlie Chaplin to avoid sticky-sweet temptations.

The Stroop Task is another canonical cognitive-control example: In this case, reading the letters R-E-D is the itch, while naming the color is the not itching. In order to successfully say that the top entry is blue, your PFC plays up the process of recognizing the color. That oh-so-responsible part of your brain coaches up the brain processes that support your goal, so that it wins out over the more habitual — in this case, linguistic — pathway.

To Cohen, the riddle of cognitive control underscores how hard it is not to do something. This is a point evidenced in clinical psychology, most famously in Daniel Wegner’s finding that if you tell someone to not think of a white bear, they’re going to be imagining polar bears in no time. If you want to “get rid” of unwanted thoughts, absorb yourself in something else. It’s built into the architecture of the brain.

Where Will Happens in the Brain