A Famous Argument Against Free Will Has Been Debunked

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sciborg2

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« on: September 11, 2019, 04:18:19 am »
A Famous Argument Against Free Will Has Been Debunked

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From a bird’s-eye view, all these cases of noisy data look like any other noise, devoid of pattern. 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.

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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. In a study of monkeys tasked with choosing between two equal options, a separate team of researchers saw that a monkey’s upcoming choice correlated with its intrinsic brain activity before the monkey was even presented with options.

In a new study under review for publication in the Proceedings of the National Academy of Sciences, Schurger and two Princeton researchers repeated a version of Libet’s experiment. To avoid unintentionally cherry-picking brain noise, they included a control condition in which people didn’t move at all. An artificial-intelligence classifier allowed them to find at what point brain activity in the two conditions diverged. If Libet was right, that should have happened at 500 milliseconds before the movement. But the algorithm couldn’t tell any difference until about only 150 milliseconds before the movement, the time people reported making decisions in Libet’s original experiment.

In other words, people’s subjective experience of a decision—what Libet’s study seemed to suggest was just an illusion—appeared to match the actual moment their brains showed them making a decision.

When Schurger first proposed the neural-noise explanation, in 2012, the paper didn’t get much outside attention, but it did create a buzz in neuroscience. Schurger received awards for overturning a long-standing idea. “It showed the Bereitschaftspotential may not be what we thought it was. That maybe it’s in some sense artifactual, related to how we analyze our data,” says Uri Maoz, a computational neuroscientist at Chapman University.

For a paradigm shift, the work met minimal resistance. Schurger appeared to have unearthed a classic scientific mistake, so subtle that no one had noticed it and no amount of replication studies could have solved it, unless they started testing for causality. Now, researchers who questioned Libet and those who supported him are both shifting away from basing their experiments on the Bereitschaftspotential. (The few people I found still holding the traditional view confessed that they had not read Schurger’s 2012 paper.)

“It’s opened my mind,” says Patrick Haggard, a neuroscientist at University College London who collaborated with Libet and reproduced the original experiments.

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. And unfortunately for popular-science conversation, Schurger’s groundbreaking work does not solve the pesky question of free will any more than Libet’s did. If anything, Schurger has only deepened the question.

Is everything we do determined by the cause-and-effect chain of genes, environment, and the cells that make up our brain, or can we freely form intentions that influence our actions in the world? The topic is immensely complicated, and Schurger’s valiant debunking underscores the need for more precise and better-informed questions.
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Wilshire

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« Reply #1 on: September 11, 2019, 11:42:49 am »
So a years old study was overturned by ... doing it again as a double blind study. Except since its 20XX we're having a computer be one of the blinds.

 It astounds me how simple things can be sometimes.
One of the other conditions of possibility.