Benjamin Libet dethroned; what replaces him?

I had never before known what the backstory was of the Libet experiments, what inspired Benjamin Libet.

And now I do.

It would seem indeed, per the author of an interesting pieceat The Atlantic, that the decade-earlier German research, now understood better today, undermines Libet's experimental angle.

But also reinforces his philosophical scrivening.

Here’s the backstory:

 In 1964, two German scientists monitored the electrical activity of a dozen people’s brains. Each day for several months, volunteers came into the scientists’ lab at the University of Freiburg to get wires fixed to their scalp from a showerhead-like contraption overhead. The participants sat in a chair, tucked neatly in a metal tollbooth, with only one task: to flex a finger on their right hand at whatever irregular intervals pleased them, over and over, up to 500 times a visit. 

The purpose of this experiment was to search for signals in the participants’ brains that preceded each finger tap. At the time, researchers knew how to measure brain activity that occurred in response to events out in the world—when a person hears a song, for instance, or looks at a photograph—but no one had figured out how to isolate the signs of someone’s brain actually initiating an action. 

The experiment’s results came in squiggly, dotted lines, a representation of changing brain waves. In the milliseconds leading up to the finger taps, the lines showed an almost undetectably faint uptick: a wave that rose for about a second, like a drumroll of firing neurons, then ended in an abrupt crash. This flurry of neuronal activity, which the scientists called the Bereitschaftspotential, or readiness potential, was like a gift of infinitesimal time travel. For the first time, they could see the brain readying itself to create a voluntary movement.

Twenty years later, Libet used this to argue for what he then sought to show by his own experiments — that “we” act before any of “us” makes a conscious decision to act.

But Bahar Gholipour says Libet got it wrong, and wrong from the start:

The Bereitschaftspotential was never meant to get entangled in free-will debates. If anything, it was pursued to show that the brain has a will of sorts. The two German scientists who discovered it, a young neurologist named Hans Helmut Kornhuber and his doctoral student Lüder Deecke, had grown frustrated with their era’s scientific approach to the brain as a passive machine that merely produces thoughts and actions in response to the outside world. Over lunch in 1964, the pair decided that they would figure out how the brain works to spontaneously generate an action.

Well, there you go.

Problem was, this was 1964. MRIs, CAT scans, none of that existed. What’s an early neuroscientist to do? This:

They had a state-of-the-art computer to measure their participants’ brain waves, but it worked only after it detected a finger tap. So to collect data on what happened in the brain beforehand, the two researchers realized that they could record their participants’ brain activity separately on tape, then play the reels backwards into the computer. This inventive technique, dubbed “reverse-averaging,” revealed the Bereitschaftspotential. 

But, what did it mean? Gholipour said that was anybody’s guess. One possibility? 

Scientists explained the Bereitschaftspotential as the electrophysiological sign of planning and initiating an action. Baked into that idea was the implicit assumption that the Bereitschaftspotential causes that action. The assumption was so natural, in fact, no one second-guessed it—or tested it.

Enter Libet:

He repeated Kornhuber and Deecke’s experiment, but asked his participants to watch a clocklike apparatus so that they could remember the moment they made a decision. The results showed that while the Bereitschaftspotential started to rise about 500 milliseconds before the participants performed an action, they reported their decision to take that action only about 150 milliseconds beforehand. “The brain evidently ‘decides’ to initiate the act” before a person is even aware that decision has taken place, Libet concluded.

Argument has been fast and furious ever since. The original attack angle was to accuse Libet of mismeasurement, especially since 150 milliseconds is pretty thin slicing.

And, Libet has had his defenders, including to fair degree, yours truly. That said, I took the findings in other directions, namely that selfhood isn’t so unitary; I didn’t see this as a proof of “determinism” at all.

Anyway, more and more neuroscientists, cognitive scientists and philosophers of mind have accepted that Libet got it all measured correctly. It was just the interpretation was wrong for many of them.

Move to 2010, as Gholipour does:

In 2010, Aaron Schurger had an epiphany. As a researcher at the National Institute of Health and Medical Research in Paris, Schurger studied fluctuations in neuronal activity, the churning hum in the brain that emerges from the spontaneous flickering of hundreds of thousands of interconnected neurons. This ongoing electrophysiological noise rises and falls in slow tides, like the surface of the ocean—or, for that matter, like anything that results from many moving parts. “Just about every natural phenomenon that I can think of behaves this way. For example, the stock market’s financial time series or the weather,” Schurger says.

“Static.” “Noise.” “Snow.” We all know this.

Surely that type of noise is random, though, and can’t be what Libet, or his German predecessors found, can it? Welll …

But it occurred to Schurger that if someone lined them up by their peaks (thunderstorms, market records) and reverse-averaged them in the manner of Kornhuber and Deecke’s innovative approach, the results’ visual representations would look like climbing trends (intensifying weather, rising stocks). There would be no purpose behind these apparent trends—no prior plan to cause a storm or bolster the market. Really, the pattern would simply reflect how various factors had happened to coincide. 

“I thought, Wait a minute,” Schurger says. If he applied the same method to the spontaneous brain noise he studied, what shape would he get?  “I looked at my screen, and I saw something that looked like the Bereitschaftspotential.” Perhaps, Schurger realized, the Bereitschaftspotential’s rising pattern wasn’t a mark of a brain’s brewing intention at all, but something much more circumstantial.

And from there, a new interpretation.

Two years later, Schurger and his colleagues Jacobo Sitt and Stanislas Dehaene proposed an explanation. Neuroscientists know that for people to make any type of decision, our neurons need to gather evidence for each option. The decision is reached when one group of neurons accumulates evidence past a certain threshold. Sometimes, this evidence comes from sensory information from the outside world: If you’re watching snow fall, your brain will weigh the number of falling snowflakes against the few caught in the wind, and quickly settle on the fact that the snow is moving downward. 

But Libet’s experiment, Schurger pointed out, provided its subjects with no such external cues. To decide when to tap their fingers, the participants simply acted whenever the moment struck them. Those spontaneous moments, Schurger reasoned, must have coincided with the haphazard ebb and flow of the participants’ brain activity. They would have been more likely to tap their fingers when their motor system happened to be closer to a threshold for movement initiation. 

This would not imply, as Libet had thought, that people’s brains “decide” to move their fingers before they know it. Hardly. Rather, it would mean that the noisy activity in people’s brains sometimes happens to tip the scale if there’s nothing else to base a choice on, saving us from endless indecision when faced with an arbitrary task. The Bereitschaftspotential would be the rising part of the brain fluctuations that tend to coincide with the decisions. This is a highly specific situation, not a general case for all, or even many, choices. 

Other recent studies support the idea of the Bereitschaftspotential as a symmetry-breaking signal.

Symmetry breaking. Like the weak nuclear force and certain particle symmetry being broken once cosmic inflation expanded enough, according to the “Standard Model”?

Why not?

It’s still possible that Schurger is wrong. Researchers broadly accept that he has deflated Libet’s model of Bereitschaftspotential, but the inferential nature of brain modeling leaves the door cracked for an entirely different explanation in the future.

So, I’ll expound my idea.

As I see it, this is similar to "virtual particles" popping up out of a "quantum foam," per an idea in quantum mechanics.

Put another way, this takes Dan Dennett's idea on how "subselves" pop up another step further, while also refuting part of it.

Those subselves, or specific actions by bigger ones of them, at least, aren't a matter of Darwinian competition. Rather, they're ultimately that mental substrate version of quantum foam.

Of course, I have long rejected Dennett's ideas that Darwinian-type evolution drives much of life outside of biological evolution. I have even more rejected the idea that algorithms are the driver. Quantum mechanics, when it comes to individual events, no matter what quantum interpretation one stakes one's life on, is not algorithmic. 

With Dennett, more than the greedy reductionism he decries in others but seems to practice all too much himself, often, I now think, it's lazy reductionism.

I've argued with Massimo Pigliucci about Libet before, as here. (Polite, not normal Internet arguing, but in the more professional sense, and we don't totally disagree on some things; in fact, we semi-agree on a fair amount of free will and volition ideas.) I could partially reconcile on Libet's interpretation of his experiments being wrong, but I've never fully bought into his interpretation in the first place. I've always interpreted them in the vein of subselves, and now, this new take on what Libet was actually finding only moves me more that way.

==

Update, Nov. 5: Bill Bryson, in his excellent new book "The Body," talks about the one-fifth second delay in optic nerve transmission speed and how the brain confabulates that to try to give a "real time" appearance of what we see. While there's no choice nor veto there, that confabulation also calls into account traditional ideas of free will, while also not at all supporting traditional ideas of determinism, either.