What Has Neuroscience Taught Us About Free Will? - Pacific Standard

What Has Neuroscience Taught Us About Free Will?

Sitting stock-still for three hours as electromagnetic waves pulse through your skull might be an underrated way to kick off your weekend.
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Sitting stock-still for three hours as electromagnetic waves pulse through your skull might be an underrated way to kick off your weekend. It's the cutting-edge approach some researchers are using to explore the biological underpinnings of free will. And why go out on a Friday night unless you're bringing along some new insight into the question of all questions?

With that in mind, I spent a recent Friday afternoon at the University of California-Santa Barbara's Brain Imaging Center. There, a team of Ph.D. students and post-docs used something called a transcranial magnetic stimulation to affect my thoughts: They held the TMS device against my head as it produced electromagnetic pulses, which stimulated my primary motor cortex and made my right hand move involuntarily. They simultaneously measured my hand muscle activity as I made a series of decisions. (The study design is still getting tweaked, so I won't get more specific.)

Broadly, they were trying to figure out if all the reasons we think we've made a decision are actually just after-the-fact rationalizations. The underlying theory they were testing holds that our brain has a bunch of automatic responses to the choices we face every day—cream or sugar, left or right, Democrat or Republican, to be or not to be—pre-programmed by our genes and by the environment around us.

It was a jarring experience that exposed me to the dystopian future of brain stimulation therapies and forced me down a rabbit hole of neuroscience research.

Here's what a typical TMS machine set-up looks like:

r3_tms

But don't be fooled by that guy's calm demeanor. After an hour of little magnetic knocks on a shallow ridge along the left-top side of my scalp, via that half-oval device on the blue-shirt guy's temple, my enthusiasm listed toward grim forbearance. The situation started to feel more like this:

clockwork_big

A Clockwork Orange. (Photo: Warned Bros.)

Here's a cross-section of the brain to illustrate where you can position TMS coils in order to stimulate different parts of the body to move, via those little knocks:

homunculus

And the first 30 seconds of this video demonstrate the whole thing in action:

This might look like a good way to cause permanent brain damage, but TMS is supposed to be very safe, having been closely scrutinized due to its potential as a depression treatment. That said, for all the different types of "brain stimulation therapies" listed here, including TMS, the National Institute of Mental Health adds that "long-term side effects are unknown."

This has been an area of inquiry in neuroscience at least since Benjamin Libet, a University of California-San Francisco scientist, started measuring brain activity while people made decisions in the 1970s and '80s. As one journalist put it: "Many philosophers and scientists have argued that free will is an illusion. Unlike all of them, Benjamin Libet found a way to test it."

And many of his academic descendants have kept pulling this thread, including my friends at UCSB. This short 2008 paper outlines some remaining controversies, including confusion about in which part of the brain a decision starts to get made (the Frontopolar and Parietal Cortex or the Supplementary Motor Area?), or, how much time elapses after the beginning of the brain activity that (for example) makes our arm move before we become conscious of our decision to move our arm? Here's a good 2014 paper that compares the competing models (the "prospective account of agency" versus the "retrospective account of agency") that map the neurological processes that give humans the feeling of "free will." Here's a recent book chapter from this year that reviews the implications of these findings for how we understand a host of societal ills, including crime (and, from the same book, addiction). And here's a 2012 paper that summarizes a decade of research into "intentional binding," which is the name for the weird wiring in our brain that makes us overlook those milliseconds between when our brain has made up its mind about some decision and when we become aware of that decision.

But, probably more interesting than all of that, here's one journalist's reflections on how a brain treatment kinda like TMS—transcranial direct current stimulation, or, tDCS—transformed her from a humble magazine editor into a super-efficient soldier of fortune in Iraq, by erasing all of her self-doubt (or listen to last month's Radiolab episode about it, here.) —Michael Fitzgerald

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