This Is Your Brain On Free Choice

Last month, a paper was published in Nature, in which Kay et al(1) were able to guess which of their stimuli a person was seeing by looking at their fMRI scans. The model looked something like this (from Kay et al's Figure 1, p. 352):


The image the participant is seeing is on the left, the numbers in the middle represent receptive fields, and the predicted brain activity is on the right. Just compare the predicted brain activity for each image to actual brain activity, and whichever matches the best is the image the person was viewing when they produced that brain activity. Simple, right? Well, not really. To be honest, I understand about .01% of what's going on in their analysis (I see the phrase "Gabor wavelet pyramid," and my eyes glaze over), and apparently I'm not alone, because despite the fact that the ability to guess what someone's seeing from their brain activity is really, really cool, the paper got no love from the blogosphere. And I was really hoping someone would post about it, so they could explain it to me.

However, a paper by Soon et al. published just this week in Nature Neuroscience(2, which makes predictions about people's behavior from fMRI data is getting all sorts of attention, with an article in Wired and the Boston Globe, as well as in diverse areas of the blogosphere (e.g., here, here, here, and here). Now, I find the other paper more interesting, because it uses underlying theory about how the visual system works in order to predict patterns of activation from patterns of input, whereas this week's paper just attempts to correlate activity with behavior, but apparently that's just me. To see why people find this new paper so interesting, though, we should take a step back, all the way to February 2007.

Back then, when time's were simpler and the dollar was worth slightly more, Haynes et al. (Haynes is one of the authors of the Soon et al. paper) published a paper in Current Biology(3) that's basically the same as this week's Nature Neuroscience paper. They asked participants to choose between two tasks (either addition or subtraction), then to "covertly maintain their intention" (I guess that just means keep it in mind, in neuroscientist-speak) during a delay, after which they would be presented with two numbers and the two possible answers (one for addition and one for subtraction), from which the participants were to select the correct one given the decision they'd made.

Since this is an imaging study, participants were having pictures of their brains taken all along, using fMRI. After everything was done, Haynes et al. used pattern recognition techniques to look for, well, patterns in the fMRI data taken during the delay (while participants were covertly maintaining their choice), and then correlate those patterns with each of the decisions. They then used the results of the pattern recognition analysis to predict which of the two decisions a participant had made. Activity in several brain regions were able to predict participants' choices, including the anterior medial prefrontal cortex, the posterior medial prefrontal cortex, the left lateral frontopolar cortex, the left frontal sulcus, the right middle frontal gyrus, the left frontal operculum, all regions associated with memory, executive functioning (e.g., planning and resource allocation), and motor control. The medial prefrontal cortex had the highest prediction accuracy, correctly predicting participants' choices 71% of the time. When thinking about this, keep in mind that this activity occurred before people actually carried out their chosen activity, so this is all activation associated with the choice itself. Or so the logic goes.

The Soon et al. paper isn't much different from the Haynes et al. paper. Once again, they gave participants two options from which they could freely choose, though in this case the choice was which of two buttons to press. While participants were making their decision, letters were scrolling across the screen, and after making the choice, participants were told remember the letter that was present when they made the decision (i.e., when they first became consciously aware of having made a choice). Once again, fMRI pictures were being taken of their brain.

As in the previous study, Soon et al. used pattern recognition models to correlate brain activity with the two choices, but this time, there was a twist. Using the letters that participants indicated were present when they made their choice, Soon et al. could estimate (within a couple hundred milliseconds) when they became consciously aware of t heir choice, and could then look at brain activity in various regions at various time intervals prior to conscious awareness. They found that activity in the frontopolar cortex (executive functioning), signals occurring up to ten second before participants became consciously aware of their decision could predict which choice they'd made with accuracy greater than we'd expect by chance. Several areas within the parietal cortex were also accurate at predicting choice at above chance levels.

What does this mean? It means that prior to our becoming consciously aware of choosing something, at least in these simple tasks, our brains have worked out what we're going to choose below the level of awareness. In other words, the unconscious mind is doing all the work. Duh. This is not all that surprising, and the only truly impressive thing about it is that the choice seems to be set so long before we're aware of making it, even when the choice is so simple (it's not like there's anything riding on it). I'd have thought things worked a bit faster than that, though I suspect part of the reason they work so slow in this case is because there are no real time pressures.

From my perspective, there's not really anything to write home about here. Unlike the Kay et al. paper, Haynes et al. and Soon et al. aren't using any new techniques or models. They're just using correlations, and my son could do that, if he had the statistical software to analyze fMRI data that is. But from the very first sentence of the Soon et al. paper, it's clear why this study has drawn people's attention. They begin their paper with:

The impression that we are able to freely choose between different possible courses of action is fundamental to our mental life. However, it has been suggested that this subjective experience of freedom is no more than an illusion and that our actions are initiated by unconscious mental processes long before we become aware of our intention to act.

Aha! Free will! People love that shit, and that's how they're thinking about the paper, as evidenced by the headlines and post titles for articles about the study, such as "Free will? Not as much as you think," "Free will as illusion," "Letting go of free will," and just, "Free will?" It's clear that people, encouraged by the paper's authors, think this data calls into doubt the existence of free will, if it doesn't debunk it altogether. But does it?

The answer, for me at least, is no, it has absolutely nothing to do with free will. Putting aside for a moment the fact that I'm not really sure what free will looks like in a non-dualist metaphysics, it's pretty clear that Soon et al.'s data really only speaks to the existence of free will in a dualist metaphysical system in which consciousness is totally separate from the physical (and unconscious) mind. Or at least, you need to posit some sort of homuncular consciousness in order for it to say anything about free will. In other words, for this study to have any relevance to free will, there would have to be this conscious system (physical or not, it doesn't matter), separate from the unconscious one, that is sitting around getting input from the unconscious system and making its own decisions freely (whatever freely means in this context). You'd have to have a conscious mind that's watching the unconscious mind, and acting separately. If this is your model of how things work in the head, then you've got more problems than this data -- you've got a hundred years worth of data to contend with, along with some difficult logical and engineering problems. If, however, you treat the conscious and unconscious minds as part of the same system, then any decision made by the latter are as free as decisions made by the former. That is, there's no reason to treat decisions made unconsciously as less free than decisions made consciously. Unless there's some property of conscious awareness that gives freedom to choices, but I have no idea what that property would be, and I don't think anyone else does either.

In sum, then, the Kay et al. study is really cool, but I don't understand it, while the Haynes et al. and Soon et al. studies are mildly interesting, but have absolutely nothing to do with free will. I blame this confusion on our continued love-affair with consciousness, which leaves us blind to the fact that consciousness is doing very little of the work in our minds, while the under-appreciated unconscious mind is doing everything and getting none of the glory. I blame Homer.

1Kay, K.N., Naselaris, T., Prenger, R.J., & Gallant, J.L. (2008). Identifying natural images from human brain activity. Nature, 452, 352-356.
2Soon, C.S., Brass, M., Heinze, H.J., & Haynes, J.D. (2008). Unconscious determinants of free decisions in the human brain. Nature Neuroscience.
3Haynes, J.D., Sakai, K., Rees, G., Gilbert, S., Frith, C., & Passingham, R. E. (2007). Reading hidden intentions in the human brain. Current Biology, 17, 323-328.


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Oh dear. Soon et al have obviously not read very much of the literature on free will, have they? Unfortunately, neither, it seems, have most people reacting to their studies ("have no idea what that property would be, and I don't think anyone else does either"). The crucial, paradoxical question riddling free will debates is this: Free will, on the face of it, seems to require that physical determinism - the idea that every process is determined by the laws of nature - is false. Unfortunately, the opposite of being determined by causal laws is ... randomness and unpredictability. And our decisions being random and utterly unpredictable isn't much more palatable than they being completely determined.

I don't - I REALLY don't - understand why people are so worried by the free will issue and at the same time systematically avoiding all the interesting literature on the subject. For an easy, rather non-technical start, may I suggest the following short articles:
Roderick Chisholm: "Human Freedom and the Self" (rather radical claim there)
Peter van Inwagen: "The Powers of Rational Beings: Freedom of the Will" and
Harry Frankfurt: "Alternate Possibilities and Moral Responsibility" and "Freedom of the Will and the Concept of a Person"
They are rather easy, probably available online and will presumably make the pseudo-problems associated with the experiments you talk about dissipate.

thank you for this. I have often wondered why the kind of dualism you describe comes up so often in neuroscience. Maybe it is not only the neuroscientists; many economists (and sociologists, political scientists, and even philosophers not concerned with the problems of free will and consciousness) unconsciously (pardon the pun) have a "homo rationalis" idea of man which leads them to equate the "self" with only the rational, and that usually means the conscious part of the mind. Ironically this view is bolstered by many philosophers stressing that conscious experience is something "different" from other phenomena (the qualia problem), which also leads to a problem because of the neuroscientific and psychological results that most of our actions take their origin not in consciousness, but in pre- or even subconscious processes.

On the "free will" issue I can also recommend this (debunking traditional notions of free will):

Or anything by Galen Strawson, Ted Honderich, or Derk Pereboom (all three philosophers)

By Peter Mexbacher (not verified) on 17 Apr 2008 #permalink

Discussions of free will certainly tend to suffer from a lack of clear definition of what the people involved mean by "free will". (I am agreeing with you here, not hinting that you're part of the problem.)

I get the impression, (from my amateurish reading of less-than-serious vaguely philosophical sources, but...) that determinism discussions tend to fall into two classes: "hard" determinism -- the physics kind, which is the one that I find most interesting, versus "soft" determinism, which seems to just be about how much circumstances affect your choices (i.e. sort of a "well, in that situation, there's really only one sensible thing to do"), which doesn't interest me.

I can propose a definition of determinism in the hard determinism sense which doesn't involve Cartesian dualism: if the "laws of physics" uniquely determine the solution to an initial value problem for the state of the universe (i.e. if the state of the universe at time t0 uniquely specifies the state for all times t>t0, or, equivalently, if there is only one solution satisfying the time evolution equations for t>=t0 with the given state at t0) then there is not free will.

Put differently, the difference between the existence or nonexistence of free will is whether the laws of physics are underdetermined i.e. if multiple solutions exist and there is no mechanism of selection between them (because if such a mechanism existed, then we would lump it in with the "laws of physics", and the problem would no longer be undetermined). The selection of the solution occurs via some in-principle-irreducible "black box" mechanism, which we could call "free will", or a "random number generator", or it doesn't really matter what we call it. Some people tend to feel that the universe being run by a random-number generator is the opposite of free will, but I think that's their problem (well, actually, I think that probably such people have unclearly-articulated-to-themselves intuitions about "free will" that aren't logically consistent).
Anyhow, if the future solutions are uniquely determined by the present state, then there's no way you can call it free will. If they're not, then haggling over what "free will" means and whether it exists is still on the table.

As far as we know, the laws of physics do imply unique solutions to given initial value problems, with the possible exception of quantum measurement which isn't understood yet. Personally, I doubt that resolution of the quantum measurement problem will change this, and that we'll still find microscopically reversible dynamics at work everywhere once we understand it.

I think that what people may mean by their comments that this study rules out free will, is that they feel that the decision-making process must be conscious to have any chance of qualifying as free will, and if it's completely unconscious, then it's clearly not free will (this would be that conscious decision-making is necessary (as opposed to sufficient) for there to be free will). This seems reasonable to me: if it's not conscious then under most reasonable definitions of free will we would agree there isn't free will. I suspect that a lot of people would also think that conscious decision-making implies free will (i.e. that conscious decisions are sufficient to establish the existence of free will, as opposed to being necessary), at which point I think one needs a proper definition of free will to proceed any further. I think that people who think conscious decision-making is sufficient to establish free will have missed the possibility that consciousness is itself the outcome of deterministic machinery. That is, there is either a mistaking of "will" for "free will", or maybe they're using some consistent definition where it all works out and hence there's nothing left in the discussion but semantics, but they have failed to state what that definition is...

So, what was my point.

Oh, yeah, it's basically, I think you're right. An immensely valuable starting point for discussions of "free will" would be a clear definition and this often seems to be lacking, and I suspect that is is often because the people talking about "free will" are guided by vague, inarticulated intuitions rather than by well-developed, crystallized ideas on it.

By El Christador (not verified) on 18 Apr 2008 #permalink

G.D. (and others), I'm not entirely unfamiliar with the literature on free will, at least up until the end of the 20th century (I don't follow it at all, so there could have been some major developments in the last 10-15 years that I don't know about). What I mean when I don't know what free will would look like in a non-dualist metaphysics, I'm thinking more about problems of agency. Where is the agent in all of this? In the "Cartesian theater" view of conscious agents that seems to go with treating studies like the one by Soon et al. as relevant to free will, there is this independent conscious agency, over and above the rest of the organism, that is making deliberate choices (free or not, we don't need to get into compatibilist/determinist debates to discuss the paper's relevance, I don't think). Under this view, the conscious mind is somehow less determined or, under some views of free will, more deliberate, than the unconscious mind, but I don't see any reason to accept that view.

And I should add that I don't think the fact that researchers can predict (really, guess after the fact) people's choices based on neural activity bears on free will regardless of whether you're a compatibilist or not. Unless you're a hard-core Cartesian dualist, your decisions, free or not, will be reflected in brain activity, and presumably this brain activity (again, whether it reflects free decisions or determined ones) will be highly correlated with particular decisions. It's a strange model in which decisions have to produce different brain activity every time you make them for those decisions to be free.

An immensely valuable starting point for discussions of "free will" would be a clear definition and this often seems to be lacking

This likely settle the question by firmly pinning it in the domain of nonsense, because there cannot be any "clear definition" of free will about which all will agree...

I think you're wrong about this one, Chris: wrong that the paper hasn't got anything new, and wrong that is only relevant to dualist accounts of FW. Here's a result that would strike many people as threatening to FW, but only because of implicit dualism: we discover that (allegedly) free choices have neural correlates. But that's not what Soon et al. did. Instead they found (perhaps better, they have interpreted their results as showing) that people's perceived choices are actually settled a massive 7 (sometimes more) seconds prior to their conscious decision. It's the timing of the decision which is important here: if is is the case that our decisions are settled at a time we take ourselves to be still deliberating, then prima facie our deliberation is epiphenomenal. Because Haynes et al. asked subjects to hold their choice in mind, no timing issue came up in their study.

So if the results actually show what the authors take them to show, they are evidence against mental causation, and mental causation is a necessary ingredient on most (maybe all) accounts of FW. A lot depends on why they only got 60% accuracy in retrodictions. If this is due to limits in our interpretive ability, then mental causation is threatened; if it is because what they detected was a disposition or inclination then it is not.

"Great post. I agree that you will need somekind of
memory technique to remember things. I recommend you to visit this website at as it has plenty of useful tips on memory techniques and ways to improve your memory. "

Neil, but what does this data say about mental causation? Wouldn't mental causation be reflected in brain activity, and wouldn't that brain activity be likely to be associated with particular choices? If that's the case, then why would unconscious activity be any different from conscious activity, in terms of mental causation?

Chris, right, mental causation could be unconscious. I spoke (and thought) badly). What I should have said is that if the researchers are right, than mental causation by the states we take to be causally efficacious is an illusion. In other words, the study would support a Wegner-like view, upon which our actions are caused by mental states, but not by conscious mental states. If that were true, then almost all extant theories of FW are false. There might be a viable account of FW to be had (actually, I have sketched an account somewhere, in response to Wegner), but none of the major contenders are viable.

Neil, I get that impression (that many contemporary theories of FW require conscious deliberation), but I think it's silly for the reasons I stated in the post. It requires the sort of dualism (even physicalism qua dualism) that just doesn't make any sense empirically. That is, it requires that there be some special property of consciousness that distinguishes it in an FW-relevant way from unconscious cognition. And I just don't see what that could be.

By the way, if I'm not mistaken (and some of you certainly know more about this than I do), unconscious mental causation would be perfectly consistent with Humean free will, right?

The fact that a decision is prepared ten seconds before we think we make the decision deliberately seems to implicate that we do not really control our behavior, not? We integrate multisensory bottom-up information, influenced by previously learned knowledge, which results in a response (affective, behavioral, ...) in some sort of automatic uninterrupted sequence of feedforward and feedback processing, regardless whether we are aware of it or not. Traditionally we believe that we can 'create' new actions, as in 'create actions without a cause' or 'create brain activity without a cause' . Instead of having a free will, it seems like the sequence of activity just happens. This doesn't mean it's not us, our behavior as a response to the environment still makes out who we are. Consciousness then, is just the awareness of what's going on.
But: I often wonder how we can avoid free will and determinism at the same time.

I don't see why the requirement for conscious mental causation requires any sort of dualism. The requirement is simply this: that the mental states we take to be causally efficacious really are causally efficacious. They might be efficacious by way of their neural realizers (I don't see any other way for them to do it myself) but that's not dualism. Its simply supervenience. If epiphenomenalism about deliberation is true, then we are radically mistaken about how we go about making decisions, and FW needs to be rethought. David Rosenthal says somewhere (in response to Libet) that that's okay, so long as our decisions really reflect our values. I guess that's the way to rescue FW in the face of epiphenomenalism about deliberation.

I'm not sure what you mean by Humean FW. Almost no philosopher in the FW debate is a Humean about causation, though Al Mele and Helen Beebee have sketeched a view of FW that incorporates that view. If you mean simple minded compatibilism (ie, an act is free so long as it is not coerced or compelled) than of course unconscious mental causation is okay. Unconscious mental causation could be incorporated into any theory except the non-causal account.

I haven't read the comments yet so maybe someone else mentioned this. However this study sure sounds like just a variation of the methods used by Libet. However many philosophers, notably Mele, point out that it conflates deciding with intending. So it's founded on a category mistake, at least as it relates to free will.

To add, your later comments are a bit off. For Libertarian Free Will what is required isn't just freedom but the ability to consciously and rationally deliberate over decisions. If decisions are decided before awareness then delibertation of the sort Libertarians require is impossible.

Even ignoring the problem of conflating different concepts (decide/intend) one should note that Libertarian Free Will is hardly the only kind of free will although some might argue it's the only kind that lines up with our linguistic and intuitive senses of free will. A Libertarian though might simply point out that just because we aren't free in this situation says little about whether we are free in other situations. That is, some are extending these conclusions (even ignoring the errors) beyond what the experiment justifies.

Just an other note. The big alternative to various variations on Cartesian minds in the Libertarian camp is radical emergence (sometimes called ontological emergence). Like Searle, I'm very, very skeptical of this since we don't see anything asserted like it anywhere but in consciousness/free will debates. The main proponent of it is O'Conner.

My main complaint is that Libertarian free will proponents seem to be using a basic agent-detection intuition and applying it to "parts." That is if we break down a person our intuitive judgments designed for detecting agents and agency break down. We assume there is some missing 'part' that's the real person. You can either assert some hidden missing part which is what the variants on Descartes do or assert that there's a mysterious 'something' greater than the sum of the parts and the laws of nature which is what O'Conner and company do.

Just a loosely related comment.
I am tired and ever more pissed off to see this cliché being spout off about anything and everything:

"there's a mysterious 'something' greater than the sum of the parts" & yada, yada, yada...

Whether it's for (synergy!) or against (as above) it's utter crap: OF COURSE "there is something greater than the sum of the parts", the way the parts are COMBINED which certainly doesn't pertain to any of the parts nor is 'mysterious' in any sense!
Profound and hermetic indeed (deep and hollow...)

I found this site by accident and was struck by the clear choice of 'determination' or 'probability' as the heart of 'agency' because that immediately shows the need for a third aspect of nature to be recognized.

Since causality seems to me to be well defined but probability does not, I wonder if probability may not be a confusion of principles. Fuzzy logic and Aristotelean might suggest something since they are not contradictory. Also Feynmann's bit about the angle of reflection equaling the angle of incidence being explanable as the cancelling of other alternatives in the calculation thus not requiring "knowing".

Agency is the issue, and intention the nub of it. The image of a paramecium following the gradient to food keeps coming to mind: a cybernetic governor which looks for all the world like me deciding I want a snack. But entire classes of paradoxes are eliminated by the introduction of an additional parameter, I understand.

By Christopher Inman (not verified) on 26 Apr 2008 #permalink

When a person asserting that something is more than the sum of its parts in these kinds of contexts (mind or will) they mean that consideration of the objects, their physical states (i.e. the state variables now identified by physics), and the laws of physics is insufficient to describe the entity.

To draw a common analogy used in these discussions. Water clearly isn't just hydrogen and oxygen atoms. But it is just hydrogen and oxygen atoms in a particular state plus the laws of physics. Libertarians who buy into ontological emergence would say that the mind is more than just the brain + the laws of physics.

Now I think such a view bunk. (The idea that there is ontological emergence) But as a philosophical position it is more subtle than some make out.

Now I think such a view bunk. (The idea that there is ontological emergence)

There is plenty of "ontological emergence" everyday, every time for everybody since ontologies pertain, not to the world or "reality" but to our models of the world.
And everyone has his "personnal" ontology which is slightly different from everyone else and furthermore is constantly and perpetually fluctuating since it is adjusted according to our present experience, including during the course of a single conversation.
This is what makes techno projects in AI like Cyc or SUO or the Semantic Web an "ongoing disaster".
I hold pretty radical views on this.

In the first post by G.D., he wonders why "people are so worried by the free will issue and at the same time systematically avoiding all the interesting literature on the subject." I suggest it is a love/hate relationship similar to chemotherapy and cancer. The intuitive free-will mindset is so deeply embedded within our social consciousness and the essential foundation for our individual security systems, that any credible data suggesting it is a false premise scares the daylights out of us. As a society, we desperately need the cure, but we most definitely don't want it. Even those empirically minded and comfortable with hard data get emotionally squeamish at the thought of dumping their security system and starting all over. Individually and as a society, we are in love with our disease; we are mesmerized by our cancer; we are infatuated with autonomy. Insidiously, free-will enhances what is left of our Self-image after the cancerous tenets of free-will have decimated it!

Contrary to popular belief, free-will is a destructively divisive, anti-social, mindset. Just the briefest glance at history goes a long way to establishing this idea. Free-will breathes life into the demoralizing concepts of culpability, inferiority, malevolence, criminal mindedness, stubbornness, sin, guilt and damnation. Once free-will has crippled our image of Self and the perception of our world during our attachment years, it casts each individual into the gamut of constant comparison; am I as successful as; am I as beautiful as; am I as smart as; am I as popular as, and the compulsion to compare never ceases. This is as true for the individual as it is for societies, cultures and nations. It is the stuff which creates bag ladies and world wars. As long as there were new frontiers to absorb this social dysfunction, mankind managed to keep one step ahead of its demise. Today, there is nowhere left to run. We can no longer escape our individual Self, or our collective Self. Mankind is face to face with the consequences of loving its disease, free-will. Mankind is now playing chicken with extinction.

Contrary to popular belief, hard determinism, with its lack of autonomy and choice, provides no structures on which to attach the demoralizing concepts of culpability, inferiority, malevolence, criminal mindedness, stubbornness, sin, guilt and damnation. Since each individual is the sum total of their genetic pre-disposition and life experience, each individual is doing exactly what they should be doing. Free-will's pervasive self-righteous judgmentalism is irrational in a determined universe. Once the irrationality of the free-will mindset is neutralized and a determined mindset takes root, knowledge is no longer twisted and contorted by a false paradigm; knowledge is free to produce understanding, and understanding is free to mature into acceptance, and ultimately, acceptance is free to heal the wounds of mankind. It may be too late. Our metaphorical Titanic may have already grazed its ice berg. If not, it still won't be easy reversing our course. Never-the-less, I believe it would be more glorious to die trying than to simply run full-speed-ahead into oblivion.

The disarray in our world today can be easily explained by mankind's insistence on living in a determined universe as if it were a free-will universe; tantamount to breathing water as if it were air. Much more in this vein of thought can be found at this website: