New hope for free will?

Last update: May 15, 2023
Reading time: 2 minutes
By Brain Matters

Did you decide of your own free will to read this article? Or is your decision the inevitable result of interactions between brain cells that proceed according to immutable laws of nature? French scientists shed new light on a classic study that decades ago dismissed free will as an illusion.

The idea that free will does not really exist was given a neuroscientific foundation by experiments conducted by physiologist Libet in the 1970s and 1980s. He asked subjects to make a wrist movement at a self-selected moment. Just over half a second before they felt the first urge to move, Libet noticed an abnormal signal on his EEG equipment, which measured electrical activity in the brain. It was concluded that the brain has already made its decision before we become aware of it.

Spontaneous activity

French researchers led by Aaron Schurger now say something else may be going on after all. They say the trigger to make the spontaneous wrist movement is due to involuntary variations in brain activity: noise that is always present in the system. They think a slow build-up of such spontaneous activity caused the increase in Libet's EEG signal. This does not mean that the decision to move the wrist has already been made unconsciously by the brain. It is only when the accumulation of noise exceeds a certain threshold that the intention to move arises.

To test that hypothesis, Schurger and his team repeated Libet's classic experiment, asking subjects to spontaneously make a hand movement whenever they wanted to. In addition, the researchers also played tones at random moments after which the movement had to be performed immediately.

Small chance

In cases where subjects responded very quickly to the tone, their EEG signal already showed a slow build-up of brain activity. Presumably, this allowed them to decide to move more quickly after hearing the tone. That buildup, according to Schurger, must in most cases have been the result of random fluctuations, since the chances of a spontaneous decision coinciding with a tone would, in fact, be very small. In short, there seems to be another (perhaps plausible) explanation for Libet's findings: In the absence of meaningful signals/reasons to move (such as hearing the tone), it could well be that this spontaneous higher activity is tipping the scale to make the decision to move the wrist.

Hard evidence for the existence of free will has still not been found. Aaron Schurger only shows another possible explanation for Libet's results. Scientists still disagree on whether free will exists or not, therefore we cannot give you an unequivocal answer to this question. So you are free to take your own position on this (or not?). 

Author: Daan Schetselaar (edited by Pauline van Gils)


  • Schurger, A., Pak, J., & Roskies, A. L. (2021). What is the readiness potential?. Trends in cognitive sciences, 25(7), 558-570.
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