Apr 15 2008

Decision Making in the Brain

Neuroscientists are wrangling with the question of decision-making and free will – by which I mean they are looking at what the brain is doing during the process of decision-making. The deeper questions of free will – what is it really and what are the implications of neuroscience for free will – are far more squirrelly. I am not convinced that free will questions are strictly scientific, at times they sound very philosophical, meaning that there are components of perspective and even meaning. But scientists and science reporters love to speculate about the deeper philosophical implications of fairly reductionist research.

The current issue of Nature Neuroscience contains a brief report about an fMRI study looking at brain function during a particular decision-making task. Subjects were asked to hit a button with either their right or left hand. The fMRI revealed that areas of their prefrontal and parietal cortex showed activity about 7 seconds before subjects hit the button. Prior research has shown that before we make a movement, about 300 miliseconds (3/10 of a second), the pre-motor cortex lights up. This makes sense, the premotor cortex is responsible for initiating movement. This new study shows that we plan our movement before we send a signal to the premotor cortex to initiate it – and then on to the motor cortex to actual perform the movement.

But here is where things get interesting. The subjects were not necessarily consciously aware of their decision until they were about to move, but the cortex showing they were planning to move became activated a full 7 seconds prior to the movement. This supports prior research that suggests there is an unconscious phase of decision-making. In fact many decisions may be made subconsciously and then presented to the conscious bits of our brains. To us it seems as if we made the decision, but the decision was really made for us subconsciously.

Then again – what does that really mean? Is not the subconscious parts of our brain still our brain – still us? This is where interpretation really gets tricky. The brain is a complex set of feedback loops interacting with itself – both conscious and subconscious. It is also not clear exactly what makes us conscious of certain parts of our brain function (those working when we are consciously thinking) and not other parts. This is not an intractable problem – we are beginning to explore which parts of the brain are responsible for attention and consciousness. It’s just really complex. And even though fMRI is a powerful tool for looking at brain function, it is still crude compared to the subtlety of the brain. It’s like trying to resolve an intricate picture that is low-resolution and therefore highly pixleated.

Another interesting aspect of the study is that the researchers claim they were able to predict which hand would press the button based upon the fMRI activity during the pre-conscious planning phase – therefore before the person was aware of their own decision. However, they could only predict with 60% accuracy – random guessing being 50%. Given the trickiness of interpreting fMRI data and performing these kinds of studies, I am not at all impressed by the 60% figure.  If it holds up to replication, and can be refined to be more accurate, then I would take it seriously. At this point I think any interpretation would be premature.

Also, it is premature to make any conclusions about how we can extrapolate from this one study. Perhaps the 7 second lag from brain activity to action is typical of this kind of task – one in which the subjects arbitrarily decide at some point to take action – and not to other tasks that involve different types of activity.

What we can say at this point is that brain function is complex (duh), and that taking action involves multiple steps – including planning, preparation/organization, and finally action. We can also conclude that subconscious brain processing contributes significantly to decision-making.

Given my recent posts concerning materialism vs dualism (does the brain cause mind), I also want to point out that this research falls squarely in the materialism camp. Causes precede their effects – brain activity precedes conscious awareness and action – the brain causes mind. That much seems pretty clear.

33 responses so far

33 thoughts on “Decision Making in the Brain”

  1. decius says:

    While philosophy’s ability to answer questions about the natural world has been largely exposed as vacuous since the onset of the Scientific Method, I agree that – in the particular case at hand – a philosophical approach may still play a major role, as long as its speculations are not removed from sound science and data-free.
    Within such a framework, I find most informative the work of Daniel Dennett, whose compatibilistic ideas seem to adequately address the problem.

    I have some reservations with regard to Dennett’s views on animal consciousness, or lack thereof. However, these views do not invalidate his insight into human consciousness, as far as I can tell.

    P.S. Did I already mention Expelled ?

  2. rbstansfield says:

    I love these findings (like the old “watch the clock…when did you decide?” experiment) that show conscious initiation of movement is kind of an illusion. People who regard free will as a necessary to soothe their angst get all riled up by this stuff. The inevitable discussion about how one can have free will if one’s brain has already planned out your actions is one part funny, two parts annoying.

    But I’ve never heard anyone wrestle with the opposite scenario. Say every movement you made had to be under your conscious control. Reaching for the cup, then, becomes a pretty complicated sequence of muscle stretches and relaxations, of comparing expected to perceived proprioceptive and tactile cues. Timing a button press involves a clock-like perception of time, and a keen sense of the physics governing your finger and the button.

    Oh, and don’t forget to breathe.

    More studies like this, please. Help people understand that:
    1) they are their brains and vice versa.
    2) “free” and “will” have yet to be empirically defined
    3) keeping your clumsy body from falling over is a full time job, and we should rejoice that consciousness isn’t necessary to do it

  3. Potter1000 says:

    Now you’re just baiting Pec with your post topics, aren’t you Dr. Novella? You feel you’re nothing without Pec nipping at you. He defines you. You love him. You need him.

    I remember reading or hearing somewhere that Einstein said his recognition that we don’t really have free will was like an endless wellspring of tolerance for people’s actions. Even though I don’t know the exact quote, I think of the idea often and find it quite beautiful. In fact, now that I just typed it, I feel like I already mentioned this on another post about freewill on this blog like a year ago. Or maybe it’s just deja vu. Oh well, it’s not like anyone will remember.

  4. Class, meet Pec’s mom.

  5. Jim Shaver says:

    Dr. Novella:

    By “free will”, don’t most people mean the innate abilities and freedoms we utilize to make conscious decisions in our lives? Which books should I read? Whom should I marry? What do I want for lunch today?

    I may have misinterpreted, but I do recall reading and hearing statements you have made that may have indicated at least some level of doubt about whether we actually have free will, as defined above, especially in the context of a materialistic world-view. But I have a terribly hard time entertaining the idea that I don’t have free will; it just seems completely obvious to me. Am I missing something important, or are the anti-free-will folks? (Not a dichotomy.)

    I hear this is a good link about the movie Expelled. There, I did my part.

  6. The question of free will is interesting, and whether or not it exists depends upon your definition, and it is difficult to impossible to propose an operational definition devoid of philosophical assumption.

    The anti-free will advocates argue that the brain is following deterministic materialistic laws of nature, and in that sense the actions of the brain are predetermined, and therefore not compatible with free will.

    However, we do make decisions. If that is all you require to accept free will, then fine, we have free will.

    On the other, other hand – making decisions is neurologically more complex and subconscious than we realize. But what does that matter as conscious and subconscious processing is a complex interactive process anyway?

    The bottom line – I’m not sure. But it may be that the question of free-will is actually a non-problem. In any case – we need to behave and operate our society as if we have free will. People still make decisions and need to be held accountable to them. And neuroscience will continue to explore how the brain functions in a reductionist way, since that approach is working quite well.

  7. weing says:

    After studying psychology in the early 70s, I came to the conclusion that freedom is an illusion and a feeling and not based on reality. I think Skinner showed that you could be conditioned to have the feeling/illusion of freedom.

  8. I’m just happy some have the free will to choose determinism/materialism.

  9. Roy Niles says:

    This study was referenced on this site as well:

    I was the first to comment, not that I’ve assumed first has all that much to do with best:

    There’s no reason to assume we don’t have free will just because we aren’t conscious of the decision making process. There’s still a decision process that our brains are just as free, or not free, to make one way or the other (assuming they were at all free to make decisions to begin with). The ability to consciously choose what information to look at, that then becomes part of the basis for making unconscious inferences, is where the nexus of the free will dilemma sits. Are those conscious choices predetermined, or at least an inevitable consequence of physical laws governing cause and effect? That’s the real question, and there has so far been no reliable answer except that on balance we can expect to be better off by acting as if we have free will, regardless of our philosophies.

  10. Jim Shaver says:

    For what it’s worth, here’s a lyric from the song “Freewill” by Rush (yeah, 80’s rock!):

    You can choose a ready guide in some celestial voice.
    If you choose not to decide, you still have made a choice.
    You can choose from phantom fears and kindness that can kill.
    I will choose a path that’s clear- I will choose Free Will.

  11. Roy Niles says:

    daedalus2u: The question is basically a philosophical one, not physiological. Of course there are situations in which we are powerless to make effective decisions, but few where we can make no decisions at all, even if the decision is to make none at all.

    The necessity to act at all times as if we do have free will involves the probability that we won’t survive if we act as if the decision to react or not react to danger, for example, will be made somewhere else. It may have been predestined that we wouldn’t have survived anyway, but are you willing (freely or not) to take that chance?

  12. pec says:

    “Causes precede their effects – brain activity precedes conscious awareness and action – the brain causes mind.”

    Sorry, no. Brain activity precedes conscious awareness, but we have no idea if it precedes subconscious “awareness.”

    Maybe this could be explored using hypnotism, which can enable communication with the “subconscious” mind.

  13. Roy Niles says:

    pec: Any time we ask anyone anything we are communicating with the so-called subconscious. Any time they answer, it’s coming in part from the subconscious. We can deduce the decision making process a lot better from answers received when the person isn’t under a suggestive influence than when he is.

  14. pec says:

    “neuroscience will continue to explore how the brain functions in a reductionist way, since that approach is working quite well.”

    Not necessarily:

  15. pec says:

    Roy Niles,

    Ok, but just because conscious awareness comes late in this kind of decision-making process is no reason to claim victory for materialism.

  16. Roy Niles says:

    pec: What the hell does my corrective comment have to do with a victory for materialism?

  17. pec says:

    I was referring to Novella’s comment, not yours. He said “the brain causes mind.”

  18. Potter1000 says:

    pec, now that you’ve made another bold claim that hypnotism allows us to communicate with the unconcious mind, may I ask that you step back from your own mind (however you think you can do that) and point your skeptical eye at that? Please provide some evidence–and then maybe we’ll just say “no, sorry.”

    While you’re at it, please provide some evidence for there being a magical non-material substance that we can’t detect that accounts for who we are. That would be great, thanks.

  19. wertys says:

    There is also functional MRI evidence (unpublished to my knowledge but presented at the IASP World Congress of Neuropathic Pain in Berlin last year) that allows neuroscientists to make predictions about a person’s pain coping style (specifically whether the subject scored high for fear-avoidant behaviour and catastrophizing) based on their pattern of fMRI activation when subjected to an experimental pain stimulus. this is an example of what was always thought to be a ‘personality’ or ‘moral strength’ contruct which has a neurophysiological correlate, in this case simultaneous bilateral activation of the anterior cingulate cortex, as opposed to other coping styles, who only had unilateral activation).
    Although early days, the data is very compelling, and accords with clinical experience in pain management, ie that there is no real way of predicting chronic pain coping styles prior to an individual getting chronic pain. It also adds support to the materialist hypothesis, apologies to pec.

  20. daedalus2u says:

    Roy, I think I agree that as individuals we should ourselves act as if we do have free will, but I think we should treat others as if (to some extent) they do not have free will, but are (to some extent) a product of their environment. To the extent that the environment is something that we as individuals generate, then we as individuals are responsible for some of the predictable consequences of that environment on individuals. If you treat people brutally, they will become brutal. Virtually every instance of high school violence the perpetrators were bullied and tried other less violent methods to get the bullying to stop. As I get older (and wiser), I see much better the predictable consequences of short sighted political policies.

    I think that one of the dangers of too much reliance on “free will”, is that those who don’t want to take responsibility for the predictable consequences of their actions when those involve how other people respond will throw up their hands and say “no one could have predicted” when the consequences were directly predictable.

  21. Roy Niles says:

    daedalus2u: Free will in fact infers that we are ultimately responsible for the consequences of our acts, because the choice was ours to make them.
    In other words, neither god nor the devil can be said to have made us do it.

    Our choices are of course limited by our abilities to carry them out and to understand and predict the consequences. We may suck at making predictions, but not because fate has robbed us of the opportunity.

  22. wertys says:

    Further to my last, here is a recent reference, though not exactly the stuff I saw presented…


  23. weing says:

    If this research pans out, the next step would be to use transcranial magnetic stimulation to allow the experimenter to manipulate the decision before the subject is aware of it. He will of course continue to think that he made the decision.

  24. Michelle B says:

    Pec wrote: …but we have no idea if it precedes subconscious “awareness.”

    subconscious “awareness”? Is that similar to unfelt “love?”

    Humans are endowed with the ability to sense/feel something when there is nothing (perhaps from developing skills to sniff out predators before it is too late).

    We now have proof that Pec is human.

  25. BA says:

    Steven is on the money with the comment that the questions of free will “research” border on unanswerable or are poor questions to answer through science. All behavior is determined but the fact behavior is highly unpredictable makes it appear as if one cannot assert determinism for human behavior. Behavior is like any other natural phenomenon. It is complexly determined by an interaction between genetic inheritance/phenotypic expression, ontongenic experience and socio-cultural influence. Attempting to preserve dualism for explaining human behavior is similar to creationists preserving the role of the creator.

  26. Roy Niles says:

    If you are arguing that all behavior is determined, it would seem to be you who are attempting to preserve dualism, not those who hold the philosophical position that it doesn’t have to be.

    Poor questions to answer through science? These are in fact questions that science itself has posed in an attempt to understand the universe. Take a look at the cover story of NewScientist, March 22-28 issue.

  27. BA says:

    Asserting determinism for behavior does not suggest a dualistic perspective. Behavior is like all other natural phenomena, beholden to the laws of the universe. Dualism posits a “special” world for the mind but the mind is a hypothetical construct that suggests there are special rules for certain human behavior like thinking. But behavior is determined by phylogenic selection, ontogenic selection and/or socio-cultural selection.

    And the argument that because NewScientist says something it is pertinent to a scientific analysis is vacuous. It often borders on Omni mag more than science at times, particularly when it comes to psychological phenomena.

  28. Roy Niles says:

    You’re assuming the article is about psychological phenomena, when in fact it’s about the quantum universe and the question of the randomness that was presumed to allow for uncertainty.

    Vacuous or not, it’s a detailed attempt to sum up what the physicists involved seem to think is a very important project, and directly involves questions of determinism in the universe.

    What does this have to do with free will (which after all was part of what this post was about), and with your comment about dualism?

    I’ll risk more vacuousness by making it simple:

    Both dualism and determinism allow for the supernatural.

    Free will and the uncertainty principle ultimately, in my view, don’t.

    Because supernatural concepts invariably posit an omniscient or omnipotent presence in nature.

  29. Nevar says:

    Here follows some incredulity, on the skeptic side 🙂

    I really don’t get the problem with consciousness or even mind. We have labelled certain experiences with these words and in my opinion that is all they are, labels for experiences. How we got to something like a consciousness or mind possibly being separate or outside of the brain is like stepping into the realm of invisible pink unicorns and teapots. I realise that the experience of consciousness is not a trivial thing, but I am not convinced it is anything more than the output of the brain. The input being anything from genes to memes.

    Sure, the resulting experience is rather astounding, but even as I sit here typing this, I can imagine being only a machine, processing things. I am perfectly comfortable with that. What an incredible machine 🙂

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