Do We Have Free Will? The Brain-Computer Duel

Berlin researchers test mechanisms involved in decision-making.

The background to this new set of experiments lies in the debate regarding conscious will and determinism in human decision-making, which has attracted researchers, psychologists, philosophers and the general public, and which has been ongoing since at least the 1980s. Back then, the American researcher Benjamin Libet studied the nature of cerebral processes of study participants during conscious decision-making. He demonstrated that conscious decisions were initiated by unconscious brain processes, and that a wave of brain activity referred to as a ‘readiness potential’ could be recorded even before the subject had made a conscious decision.

How can the unconscious brain processes possibly know in advance what decision a person is going to make at a time when they are not yet sure themselves? Until now, the existence of such preparatory brain processes has been regarded as evidence of ‘determinism’, according to which free will is nothing but an illusion, meaning our decisions are initiated by unconscious brain processes, and not by our ‘conscious self’. In conjunction with Dr. Benjamin Blankertz and Matthias Schultze-Kraft from Technische Universität Berlin, a team of researchers from Charité’s Bernstein Center for Computational Neuroscience, led by Dr. John-Dylan Haynes, has now taken a fresh look at this issue. Using state-of-the-art measurement techniques, the researchers tested whether people are able to stop planned movements once the readiness potential for a movement has been triggered.

“The aim of our research was to find out whether the presence of early brain waves means that further decision-making is automatic and not under conscious control, or whether the person can still cancel the decision, i.e. use a ‘veto’,” explains Prof. Haynes. As part of this study, researchers asked study participants to enter into a ‘duel’ with a computer, and then monitored their brain waves throughout the duration of the game using electroencephalography (EEG). A specially-trained computer was then tasked with using these EEG data to predict when a subject would move, the aim being to out-maneuver the player. This was achieved by manipulating the game in favor of the computer as soon as brain wave measurements indicated that the player was about to move.

Photo of a woman in a EEG cap looking at a computer monitor.
This image shows a participant during the experiment. Credit: Charité, Carsten Bogler.

If subjects are able to evade being predicted based on their own brain processes this would be evidence that control over their actions can be retained for much longer than previously thought, which is exactly what the researchers were able to demonstrate. “A person’s decisions are not at the mercy of unconscious and early brain waves. They are able to actively intervene in the decision-making process and interrupt a movement,” says Prof. Haynes. “Previously people have used the preparatory brain signals to argue against free will. Our study now shows that the freedom is much less limited than previously thought. However, there is a ‘point of no return’ in the decision-making process, after which cancellation of movement is no longer possible.” Further studies are planned in which the researchers will investigate more complex decision-making processes.

About this neuroscience research

Source: Dr. John-Dylan Haynes – Charité – Universitätsmedizin Berlin
Image Credit: The image is credited to Charité, Carsten Bogler
Original Research: Full open access research for “The point of no return in vetoing self-initiated movements” by Matthias Schultze-Kraft, Daniel Birman, Marco Rusconi, Carsten Allefeld, Kai Görgen, Sven Dähne, Benjamin Blankertz, and John-Dylan Haynes in PNAS. Published online December 14 2015 doi:10.1073/pnas.1513569112


The point of no return in vetoing self-initiated movements

In humans, spontaneous movements are often preceded by early brain signals. One such signal is the readiness potential (RP) that gradually arises within the last second preceding a movement. An important question is whether people are able to cancel movements after the elicitation of such RPs, and if so until which point in time. Here, subjects played a game where they tried to press a button to earn points in a challenge with a brain–computer interface (BCI) that had been trained to detect their RPs in real time and to emit stop signals. Our data suggest that subjects can still veto a movement even after the onset of the RP. Cancellation of movements was possible if stop signals occurred earlier than 200 ms before movement onset, thus constituting a point of no return.

“The point of no return in vetoing self-initiated movements” by Matthias Schultze-Kraft, Daniel Birman, Marco Rusconi, Carsten Allefeld, Kai Görgen, Sven Dähne, Benjamin Blankertz, and John-Dylan Haynes in PNAS. Published online December 14 2015 doi:10.1073/pnas.1513569112

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  1. I have to question the interpretation of the entire premise. The meaning of the ‘readiness potential’ is perhaps not so closely tied to free will / determinism as presented. It appears that the RP could be nothing more than an indication of preparedness and reaction time offset instead of anything more esoteric.
    Consider that when we see something, it is always in the past. The act of seeing as perception actually occurs in the brain. The eye transmits neural signals to the brain, and that takes time after the rods and cones have actually received stimulation. Then the neural signals are processed to produce an interpretation. That also takes time. The actual perception takes place after that scene which was perceived has already moved into the past.
    Any decision made can be said to have a size, or a complexity. I can decide to twitch my hand. Or I can decide to grab my coffee cup. Or I can decide to play “Twinkle, Twinkle” one handed. The complexity of the decision varies. Would the RP also vary in some parallel way? Doubtful, as playing an extended phrase on a piano, even one handed, would allow for enough time to pass that interference and response reactions could affect the outcome.
    The RP seems to indicate nothing more than a ‘readiness’ condition of a completed evaluation process that precedes actual action.
    For an analogy, consider a computer game. A button is pressed. That will cause some internal processing. It may ’cause’ something on the screen to move to the left. Internal to the program there is a subroutine or function that will start to move that icon. There is a point in the running of the program when that routine is next to run. It is possible to interrupt the program before it does, but at that instant, the specific routine in immanent. This is the RP for the computer, the indication that a routine capable of producing an externally observable effect is about to be executed.
    Within a mind, the RP is just a signal for ‘action immanent’ and a function of reaction time. This is why there is a ‘point of no return’, as indicated above. There exists a time when reaction to a new stimulus is too late to change an initiated action.

  2. Whether or not a person vetoes a prior decision outcome is determined by another decision. If we realize that the vast neuronal network that performs the extremely complex and hidden process we call decision-making is the same for all decisions ‘we’ make, then we can see that whether or not we have Free Will is completely a matter of whether ‘we’ control that vast and complex process of decision-making. Since we are not even aware of much of what goes on in that process, isn’t it ridiculous to assume that ‘we’ can control what goes on in it and therefore can determine its outcomes? And what does ‘control’ imply? Doesn’t control require prior choice of how to influence the thing being controlled? Therefore how could you have prior choice of how to control a decision process without making a decision of which way to make that process come out? That would mean that you had already decided the outcome of the decision you would be controlling. Once you realize that controlling a decision process is physically and logically impossible, it shouldn’t be hard to see that Free Will is an illusion and that the veto idea is a last-ditch and failed effort to salvage it. Look for my ‘diary’ named “Six Things I Can’t Do” on for more reasons to realize that Free Will is an illusion.

    1. @Thomas Gillis – OK, I’ll bite. I see that the link goes to a page mostly about religion though that “Six Things …” isn’t directly so, but a quick look at them makes me skeptical. It is just a statement of “no” something I rarely am interested in.
      Irregardless… Please tell me what “Free Will” is then.

      1. ..FREE WILL could mean.. we are free to will whatever we like using brain conditioned by its enviroment or abort upon reflaction, all within less then 1/2 sec

  3. I’ve gone round and round on this a fair amount, but be clear on the meaning of the argument. This is primarily not about science, but about religion. The term “Free Will” is mostly meaningless in any real sense. There are usually only a few potential responses to any situation… Fight, flight, buy him a beer or bribe someone to beat the tar out of him only raises the options to 4.. Yes, we as students of the biological processes of humanity may think of this as relating to the Nature Nurture debate, but that is not how it plays out. The players that have a dog in this fight are the militant atheists who want to disprove the existence of Free Will, because in their terms, that disproves the existence of God, since that is a requirement of most models of religions with deities. All ideologists give me acute gas.
    Think about it objectively. What does Free Will mean? It is not a term from science, it comes from religion, just like the word “divine”. Study it in terms of neuroscience, but be aware of how it is used and interpreted or your research will be misused by people that are not thinking the same things you are and have very different agendas.
    Having looked at the question for some time, I finally concluded… without free will, you couldn’t play chess … unless you think that is programmed into our neurology. You can only make tests that are so complicated, but I know people that lead their lives just like a chess game.

  4. ..persons must be totally without preconceptions, open-minded and expect the unexpected which can be easier done while in ‘focused zone’

  5. The free will-determinism debate, like the mind-body debate, is a most interesting subject of scientific study. It is so intriguing because it contains the essence of philosophy and morality and goes to the very root of who we individually as social persons, are. I think discussions on this subject, aided by an expanding corpus of scientific knowledge and technological advancements in the field of neuroscience, will be fruitful but any final answer to the question of whether and under what set of circumstances we may be said to exercise free will may still prove illusive.

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