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Tuesday, April 16, 2013

You only think you have free will


The more we learn about the brain, the less control we seem to have over our own thoughts and actions. We feel fully conscious and in command of the decisions we make. We also feel as if all our thoughts are coming from a single entity in a united all-controlling mind. None of that is true. Need some evidence? Chun Siong Soon and his colleagues designed an experiment to illustrate the order of events between the conscious decision to do something and the action itself. Spoiler alert: the action comes first.

The researchers used some rather nuanced experiments to suss out the timing between decision and action. Briefly, numbers were flashed on a screen in front of 18 volunteers while fMRI machines recorded their brain activity. At some point, and at their own volition, the participants decided to either add or subtract the next two numbers shown. They recorded both the moment of that decision and the answer they got. You can read a more complete explanation at Why Evolution is True.

What were the results?

Four seconds before the person stopped the clock with the thought, ‘I’ve now decided that I will be adding the next two numbers I see’, his brain activity indicated that he would be performing that action. In other words, the researchers could see the forthcoming action take shape in the subject’s brain well before he himself was aware of having decided anything. Not only that, but researchers were able to predict with 59% accuracy whether the forthcoming math operation would be addition or subtraction. Remember, the scientists were basing this prediction on brain activity occurring some time before the person himself knew when or what the next mathematical operation would be.

This phenomenon has been dubbed the 'Bereitschaftspotential' (German for 'readiness potential'), or BP, and it suggests that we can at best veto an action the unconscious parts of our brains have already decided to take. Similar experiments have shown that the BP can occur up to ten seconds before the conscious part of our brains gets clued in.  Needless to say, this is completely counterintuitive and could mean that many of our ‘decisions’ are actually rationalizations after the fact. For whatever reason, part of our brains wants to perform an action and it convinces the aware part of us that that’s what we had planned all along.


To be clear, none of this changes the fact that we really feel as if we are the masters of our own behavior, nor does it alter our responsibility for our conduct. Our actions have consequences for us and others regardless of what part of our brains instigated them.


Soon, C., He, A., Bode, S., & Haynes, J. (2013). Predicting free choices for abstract intentions Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1212218110.