Friday, April 19, 2013

Free Will, continued - Prior unconscious brain activity predicts choices for abstract intentions!

I've been running a thread on free will and neuroscience in this blog, recently noting comments by Nahmias:
...As long as people understand that discoveries about how our brains work do not mean that what we think or try to do makes no difference to what happens, then their belief in free will is preserved. What matters to people is that we have the capacities for conscious deliberation and self-control that I’ve suggested we identify with free will.
...None of the evidence marshaled by neuroscientists and psychologists suggests that those neural processes involved in the conscious aspects of such complex, temporally extended decision-making are in fact causal dead ends. It would be almost unbelievable if such evidence turned up.
Almost unbelievable appears to have happened, with this from Soon et al.. Interestingly, they identified a partial spatial and temporal overlap of choice-predictive signals with activity in the default mode network I reviewed in this past Monday's post. The abstract:
Unconscious neural activity has been repeatedly shown to precede and potentially even influence subsequent free decisions. However, to date, such findings have been mostly restricted to simple motor choices, and despite considerable debate, there is no evidence that the outcome of more complex free decisions can be predicted from prior brain signals. Here, we show that the outcome of a free decision to either add or subtract numbers can already be decoded from neural activity in medial prefrontal and parietal cortex 4 s before the participant reports they are consciously making their choice. These choice-predictive signals co-occurred with the so-called default mode brain activity pattern that was still dominant at the time when the choice-predictive signals occurred. Our results suggest that unconscious preparation of free choices is not restricted to motor preparation. Instead, decisions at multiple scales of abstraction evolve from the dynamics of preceding brain activity.
And, a chunk from their discussion:
It is interesting that mental calculation, the more complex task, had less predictive lead time than a simple binary motor choice in our previous study. This could tentatively reflect a general limitation of unconscious processing in the sense that unconscious processes might be restricted in their ability to develop or stabilize complex representations such as abstract intentions. It is also worth noting that both studies showed the same dissociation between cortical regions that were predictive of the content versus the timing of the decision. This implies that the formation of an intention to act depends on interactions between the choice-predictive and time-predictive regions. The temporal profile of this interaction is likely to determine when the earliest choice-predictive information is available and might differ between tasks.
There was a partial spatial overlap between the choice-predictive brain regions and the DMN. Interestingly, the state of the DMN (default mode network) during the early preparatory phase still resembled that during off-task or “resting” periods. This lends further credit to the notion that the preparatory signals were not a result of conscious engagement with the task. Furthermore, the spatial and temporal overlap hints at a potential involvement of the DMN in unconscious choice preparation.
To summarize, we directly investigated the formation of spontaneous abstract intentions and showed that the brain may already start preparing for a voluntary action up to a few seconds before the decision enters into conscious awareness. Importantly, these results cannot be explained by motor preparation or general attentional mechanisms. We found that frontopolar and precuneus/posterior cingulate encoded the content of the upcoming decision, but not the timing. In contrast, the pre-SMA predicted the timing of the decision, but not the content.


  1. THW Comments:

    (By mistake, my fat thumb deleted a comment from reader THW, which I was reading on my iPad while on the road. I just found the email with the comment and so paste it in here:

    Well, choices must come from somewhere, no? And if not from some earlier unconscious activity (appraising the situation, one's goals, etc.), then they'd have to somehow come from nothing. Consciousness must depend on unconscious brain activity lest we accept substance dualism.

    The nub of all this is that we don't have to decide yea or nae about free will. It doesn't have to come down to accepting or rejecting 'free will' but what can and does 'free will' mean, how does the terminology function? How do we have free will as we commonly conceive of it and how don't we have free will as we commonly conceive of it. This is a very philosophical matter that hangs on basic assumptions about our self concept and how the deliverances of science affect those assumptions.

    In short, suggesting or implying that free will hangs in the balance is going too far. We should be talking about what the phrase can mean, instead of putting on trial the way the phrase is commonly used or meant (which is pretty confused, actually).

    Dennett's "Freedom Evolves" is pretty good on this topic. He discusses "free will worth wanting." We don't want a confused and incoherent 'free will' anyway, so we shouldn't sweat tweaking the concept some to come up with a version "worth wanting." So much of philosophy hangs on one's ability to give up dogmatic assumptions... Disagreement persists because folks fail to question their dogmatic assumptions. Free will is a paradigm case.

  2. FWIW, I just ran into Benjamin Franklin's view on decision making:

    Franklin wrote:

    …To get over this, my Way is, to divide half a Sheet of Paper by a Line into two Columns, writing over the one Pro, and over the other Con. Then during three or four Days Consideration I put down under the different Heads short Hints of the different Motives that at different Times occur to me for or against the Measure. When I have thus got them all together in one View, I endeavour to estimate their respective Weights; and where I find two, one on each side, that seem equal, I strike them both out: If I find a Reason pro equal to some two Reasons con, I strike out the three. If I judge some two Reasons con equal to some three Reasons pro, I strike out the five; and thus proceeding I find at length where the Ballance lies; and if after a Day or two of farther Consideration nothing new that is of Importance occurs on either side, I come to a Determination accordingly.

    And tho’ the Weight of Reasons cannot be taken with the Precision of Algebraic Quantities, yet when each is thus considered separately and comparatively, and the whole lies before me, I think I can judge better, and am less likely to take a rash Step; and in fact I have found great Advantage from this kind of Equation, in what may be called Moral or Prudential Algebra.

  3. That is so interesting. To think "free will" is being brain scan monitored! It is that eternal question about free will, but I think even so, the brain will show free will no matter what the science behind it.

  4. Jani Miettinen6:18 AM

    How could you investigate how food preferences are made if test subjects are given a choice between a yellow candy and a blue candy? I guess it would not be a meaningful test.

    As well I really cannot accept that free will, if it exists, could ever be monitored in a situation where only few outcomes are accepted.

    Doesn't this kind of test situation itself prime brain (or mind) already to something that has to be within predetermined limits? And, predetermination, as far as I know, means absence of free will at least to some degree.

    And, the problem is that even our upbringing and education limit our choises. You are not free to kiss attendant even if that was the only way to express you free will...