An update on the science of ‘free will’

I want to point to an excellent article by Gholilpour in the Atlantic Magazine that describes a reinterpretation of experiments by Libet taken to suggest that our brains 'decide' to initiate a movement before our subjective awareness of intending to initiate that movement. A 'readiness potential' is observed about 500 msec before an action occurs, while a subject reports initiating that action about 150 msec before it occurs. Gholilpour points to work of Schurger and colleagues that suggests that the readiness potential is not the mark of a brain's brewing intention, but something much more circumstantial.

...Schurger and his colleagues ... 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.

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 readiness potential 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.

The name Schurger rang a bell with me, and so I did a MindBlog search, only to discover that I had reported Schurger's work in a 2016 post "A 50 year misunderstanding of how we decide to initiate action - our intuition is valid". I then proceeded to completely forget about it when I was preparing a subsequent 2019 lecture mentioning Libet's work. The conventional dogma that we are 'late to action' was apparently burned into my brain - most embarrassing. (I've now inserted the new perspective into four of my web lectures, dating as far back as 2012). The real clincher is...

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.

Gholilpour points out that this does not resolve the question of free will, it only deepens the question, which is the subject of an intensive collaboration between neuroscientists and philosophers, backed by $7 million from two private foundations, the John Templeton Foundation and the Fetzer Institute.