Most of you here have read Blindsight
. Some of you have made it almost to the end. A few have even got as far as the references (I know this, because some of you have asked me questions about them). And so you might remember that old study Libet did back in the nineties, in which it was shown that the body begins to act on a decision a full half-second before the conscious self is aware of having made
the decision. A lot of Blindsight
's punchline hung on this discovery— because obviously, whatever calls an action into being must precede it. Cause and effect. Hence, the johnny-come-lately sense of conscious volition is bogus. We are not in control. I mean, really: a whole half a second
Half a second? Chun Siong Soon and his buddies piss
on Libet's half a second. Nature Neuroscience
just released a study
that puts Libet's puny electrodes to shame; turns out the brain is making its decisions up to ten full seconds
(typically around seven) before the conscious self "decides" to act.
Ten whole seconds. That's longer than the attention span of a sitting president.
It all comes down to stats. Soon et al
took real-time fMRI recordings of subjects before, during, and after a conscious "decision" was made; then they went back and looked for patterns of brain activity prior to that "decision" that correlated with the action that ultimately occurred. What they found was a replicable pattern of brain activity that not only preceded the decision by several seconds, but which also correlated with the specific "decision" made (click a button with the right or the left hand). (Interestingly, these results differ from Libet's insofar as subjects reported awareness of their "decision" prior
to the activation of the motor nerves, not afterwards. Whereas Libet's results suggested that action precedes conscious "decision"-making by a very brief interval, Soon et al
's suggest that actual decision-making precedes conscious "decision"-making by a much longer one. Bottom line is the same in each case, though: what we perceive as "our" choice has already been made before we're even aware of the options.)
This isn't exactly mind reading. Soon and his buds didn't find a circuit that explicitly controls button-pressing behavior or anything. All they found was certain gross patterns of activity which correlated with future behavior. But we could not read that information if the information wasn't there; in a very real sense, your brain must know what it's going to do long before you
Obviously this can't be the whole story. If the lag between processing and perception was always that long, we would feel no sense of personal agency at all. It's one thing to think that you told your muscles to leap from the path of an approaching bus when the time discrepancy is a measly 400 millisecs; but not even organisms with our
superlative denial skills could pretend that we were in control if our bodies had leapt clear ten seconds before it even occurred to us to move. So I would think this is more proof-of-principal than day-in-the-life. Still. As IO9 points out
, given these results, how long before we can do without that stupid conscious part of us entirely?Wired's online coverage
is a bit more defensive. They bend over backwards to leave open some possibility of free will, invoking the hoary old "maybe free will acts as a veto that lets us stop
the unconscious decision." But that's bogus, that's recursive: if consciousness only occurs in the wake of subconscious processing (and how could it be otherwise? How can we think anything
before the thinking neurons have fired?), then the conscious veto will have the same kind of nonconscious precursors as the original intent. And since that information would be available sooner at the nonconscious level, it once again makes more sense to leave the pointy-haired boss out of the loop entirely.
But I'm going to take a step back and say that everyone
here is missing the point. Neither this study nor Libet's really addressed the question of free will at all. Neither study asked whether the decision-making process was free
; they merely explored where it was located
. And in both cases, the answer is: in the brain. But the brain is not you: the brain is merely where you live. And you, oh conscious one, don't make those decisions any more than a kidney fluke filters blood.
(Oh, and I've figured out who the Final Cylon is. For real this time. Romo Lambkin's cat.)
Labels: blindsight, neuro, science