The question of whether or not human beings possess free will is a source of much contention, particularly between neuroscientists and philosophers. A new study pitted humans against a computer to test whether our conscious decisions are actually determined by unconscious processes. Perhaps, the premise suggests, we only think we have free will when making a choice.

Researchers at the Charité’s Bernstein Center for Computational Neuroscience targeted an established brain activity pattern known as “readiness potential.” This pattern precedes every decision you make. Only after you’ve got the pattern do you make the choice.

To double check this finding, the researchers pitted volunteers against a computer designed to check whether people went on auto-pilot after readiness potential kicked in, and published their results in the Proceedings of the National Academy of Sciences. The volunteers were told that they were going to play a game with the computer. During the game, they would make decisions about when to push a button. The computer would try to predict when they were going to push the button and then put out a stop signal. If the volunteer pushed anyway, they’d lose points. If they successfully pressed the button without being predicted, and they’d gain points.


But the game was sort of rigged. While playing, the subjects wore an EEG (electroencephalogram) cap that was designed to give the computer an advantage. The researchers had programmed the computer to recognize the readiness potential, which only arises in the last second before the decision. The computer sensed this pattern just before a person moved, so it could beat the human subject to the punch. If people were on autopilot, only thinking that they made a conscious decision, they wouldn’t be able to “veto” their pre-determined choice to move, and the computer would win every time.

The computer did not win every time. People do have conscious control of their actions after their state of readiness potential has kicked in—but only up to a point. If people saw the stop signal less than 200 milliseconds before their “movement onset,” they would lose to the computer.


Still, if you believe the scientists’ estimation of free will, this shows that the state of “readiness potential” doesn’t govern our brain. We can consciously snap out of decisions that it unconsciously prepares us to make. What do you think? Is this computer testing for free will? Or just reflexes? Or something else entirely?


Image via Warner Brothers