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Libet and Another Free Will Thought Experiment

8/14/2015

6 Comments

 
Picture
Will he choose the left or right cup? Why? And when?
In 1983, Benjamin Libet conducted what is perhaps the most famous experiment in neuroscience, the results of which called into question the common beliefs we have about free will and whether or not we are in control of our decisions.  What kind of experiment could do that? Did Libet give people difficult choices and ask them to do the opposite of what they really wanted to do? Or maybe he asked them to plan an action, wait, and then attempt to carry it out precisely. No, Libet's research methods were much simpler:

"Researchers...would ask each participant to sit at a desk in front of the oscilloscope timer. They would affix EEG electrodes to the participant’s scalp, and would then instruct the subject to carry out some small, simple motor activity, such as pressing a button, or flexing a finger or wrist. ... During the experiment, the subject would be asked to note the position of the dot on the oscilloscope timer when "he/she was first aware of the wish or urge to act" (control tests with Libet's equipment demonstrated a comfortable margin of error of only +/-50 milliseconds). Pressing the button also recorded the position of the dot on the oscillator, this time electronically. By comparing the marked time of the button's pushing and the subject's conscious decision to act, researchers were able to calculate the total time of the trial from the subject's initial volition through to the resultant action. On average, approximately two hundred milliseconds elapsed between the first appearance of conscious will to press the button and the act of pressing it.

Researchers also analyzed EEG recordings for each trial with respect to the timing of the action. It was noted that brain activity involved in the initiation of the action, primarily centered in the secondary motor cortex, occurred, on average, approximately five hundred milliseconds before the trial ended with the pushing of the button. That is to say, researchers recorded mounting brain activity related to the resultant action as many as three hundred milliseconds before subjects reported the first awareness of conscious will to act. In other words, apparently conscious decisions to act were preceded by an unconscious buildup of electrical activity within the brain."


Since then, Libet's experiments have been offered as support of the theory that consciousness is merely a side-effect of neuronal functions, an "epiphenomenon" (a secondary phenomenon that occurs alongside or in parallel to a primary phenomenon) of our brain states.

This brings us to this week's thought experiment: Land of the Epiphens.

-------------------------------------------------
     Epiphenia was a remarkable planet. So like Earth in appearance, and yet its inhabitants were different in one remarkable way. As one of them, Huxley, explained to the visiting Earthling Dirk, the Epiphens had long ago 'discovered' that their thoughts did not affect their actions. Thoughts were the effects of bodily processes, not the other way around. Dirk found this baffling.
     "You can't really believe this," he protested to Huxley. "For instance, when we met in this bar, you said, 'Gee I could kill for a beer,' and ordered one. Are you saying that the thought 'I want a beer' had no effect on your actions?"
     "Of course it didn't," replied Huxley, as though the question were idiotic. "We have thoughts and these often precede actions. But we know full well that these thoughts aren't causing the actions. My body and brain were already gearing up to order a beer. The thought 'I could kill for a beer' was just something that popped into my head as a result of what was happening in the physical brain and body. Thoughts don't cause actions."
     "For Epiphens, maybe," replied Dirk.
     "Well I can't see what's different about humans," said Huxley. And for a while at least, nor could Dirk.

Baggini, J., The Pig That Wants to Be Eaten, 2005, p. 61.
-------------------------------------------------

Unsurprisingly, there have been several criticisms levelled at the Libet experiment and the conclusions that have been drawn from it. There's the "disconnect criticism" (this doesn't really apply to real life), the "timing criticism" (the choosing self and reporting self aren't perfectly synched), the "spontaneous activity criticism" (this is just lowering a choice to the random noise in our motor system that is always operating below the normal threshold of a decision), and the "only deterministic on average criticism" (28% of the original experiments actually showed at least one instance of brain activity after the reported decision).

Each of these criticisms are enough to cast serious doubt on the Epiphens' discovery that their thoughts did not affect their actions, as well as on the belief of free will determinists like Sam Harris who think their position has been scientifically proven correct. I've already written two different blog posts (1,2) about my compatibilist position in the free will debate, so I'll just add another criticism to the Libet experiment that I haven't seen before.

At the beginning of the experiment, participants were instructed to “let the urge [to move] appear on its own at any time without any pre-planning or concentration on when to act.” To me, this is precisely the beginning of when the brain would begin to prepare to act. This is basically an instruction to the subconscious thinking system 1 that Daniel Kahneman wrote about in Thinking, Fast and Slow. If our neuroscience was sophisticated enough to pick this up, I imagine some change would show up in the brain as soon as this instruction was given—long before the only change Libet was looking for in the secondary motor cortex. The fact that Libet (sometimes!) found a change bubbling up from the subconscious before we made a final decision isn't really surprising at all. This can and does happen all the time. But just as instructions coming from experimenters could cause this chain reaction to begin, so can instructions from ourselves after conscious, rational, system 2 thinking sessions. This isn't "free will" in its most extreme definition—it just brings me back to the compatibilist position I've taken where we have freedom to choose from among the many influences we have experienced—but it is another strong argument against the most extreme determinism that is out there in the land of the epiphens.
6 Comments
atthatmatt link
8/15/2015 12:08:12 pm

Your closing thought reminds me of this counter-intuitive brain function. We tend to intuitively model the brain as sitting idle until called on to do something, then figuring out the best option, then executing it. But what really happens is the brain is constantly generating many possible options and pushing them toward action and then a higher part suppresses all but one action. (The Tell Tale Brain pg 124) https://books.google.com/books?id=hSswinQcxY8C&pg=PA124&lpg=PA124&dq=brain+system+suppresses+all+but+one+option&source=bl&ots=ZB7afMS2n3&sig=TmKiGd9XpIWoktD0VG-5Nf7ITWM&hl=en&sa=X&ved=0CB4Q6AEwAGoVChMIsvPWheGrxwIVCdWACh0hyQo8#v=onepage&q=suppresses%20all%20but%20one&f=false

So it's worth questioning if the framework of the "free will" question is wrong. Maybe the reason we argue about its existence is that we got it inverted and really we have "free won't."

This way of thinking about it feels more consistent to me. It helps explain why I intuitively think of my brain/body as a large number of simple-minded actors that have to be herded in one direction. A herd of stupid animals has its own kind of logic and will get things done, particularly with a peer-leader, but it can be part of a much larger plan if it has a smarter herder directing it. Still, the herd doesn't directly respond to orders. The herder has to manipulate the herd's natural reactions. So the herder doesn't have the "free will" to go to the field they have the "free won't" to prevent anything other than going to the field. This framework also parallels how I think about other organizations, like bureaucracies. You don't really have the power to get anything done, you just have the power to prevent things from getting done.

This framework also agrees with the reality that we learn through trial-and-error and we think with analogies. Once something exists we have the freedom to allow or forbid it. But we can't seem to get directly to a new thing. We can only throw possibilities at the wall until something sticks.

Reply
@EdGibney link
8/17/2015 03:18:01 am

Our "free won't" is definitely another established way of looking at this issue. I almost quoted this from the wiki on Libet, but elected not to go down that path:

"Libet finds that conscious volition is exercised in the form of 'the power of veto' (sometimes called "free won't"); the idea that conscious acquiescence is required to allow the unconscious buildup of the readiness potential to be actualized as a movement."

To me, this ability to reject chemical urges is what distinguishes our consciousness from other life forms like plants. It's unclear how many other animals have this "free won't" too, but I'm pretty sure my stubborn dog does!

I found this in an old blog post from Michael Shermer too (http://www.michaelshermer.com/2012/08/free-wont/):

"Support for this hypothesis may be found in a 2007 study in the Journal of Neuroscience by neuroscientists Marcel Brass and Patrick Haggard, who employed a task similar to that used by Libet but in which subjects could veto their initial decision to press a button at the last moment. The scientists discovered a specific brain area called the left dorsal frontomedial cortex that becomes activated during such intentional inhibitions of an action: “Our results suggest that the human brain network for intentional action includes a control structure for self-initiated inhibition or withholding of intended actions.” That’s free won’t."

I think the "won't" is an important interrupter, but I think of it as allowing our rational mind to insert a "will" into the equation. The "won't" gives us a chance to choose a different influence than we might otherwise follow.

(Interesting you say that about bureaucracies. I used to work in the FBI and Secret Service as an internal management consultant tasked with making the bureaucracies run more efficiently. It was hard work, but we had successes. They can be changed to go in new directions as well as stopped from repeating past mistakes. But maybe you're just talking about cogs in the system rather than architects of the system?)

Reply
atthatmatt link
8/17/2015 07:33:34 pm

Comparing people to dogs is interesting. Dogs can obviously be conditioned, which doesn't seem like it should qualify as consciously choosing something. Still, it's hard to distinguish between a being making conscious-but-short-sighted choices and a being acting purely on urges. People act on their urges to make short-sighted decisions all the time, but we still give them credit for consciousness will/won't. I mean, how to you distinguish between something having the ability, and never/rarely choosing to use it, vs something not having the ability?

So you figure the won't is just something we use if we have a will that needs to override an urge?

Yeah, I mean individuals. By definition they're hierarchical organizations, so if someone at the top wants something to happen it generally does, since that's what it's set up to do. But the people at the top aren't the only people who want something, so they set up the rules such that everybody has the power to stop something on their own, but nobody has the power to do something on their own. That way it's hard to organize a coup. A bureaucracy is kind of like an artificial herd. If a herder could build a herd that didn't wander off on its own, that just stayed put when it wasn't being herded, they probably would. That's how we think of our brain, as an artificial herd, but in reality it's a natural herd that likes to do its own thing(s).

Reply
@EdGibney link
8/18/2015 01:54:19 am

"So you figure the won't is just something we use if we have a will that needs to override an urge?"

That sounds about right. The won't and the will are just two sides of making a choice, which is what I think the free will argument boils down to--whether or not we could choose to do otherwise. It reminds me of business school strategy classes where some expert defined strategy as deciding what NOT to do. If you just do everything you are capable of, you aren't really being strategic with your resources, and you are wasting assets and opportunities. That's not a bad way of looking at the people/things who have freedoms to choose but never/rarely do--they are wasting their opportunities.

Reply
atthatmatt link
8/18/2015 07:51:24 pm

Looks like the technical term for it might be "conation" http://www.edpsycinteractive.org/topics/conation/conation.html

Reply
@EdGibney link
8/19/2015 01:51:27 am

Yay, more jargon! That's a good find listing out 1) cognition, 2) affect, and 3) conation, although I'm sure I'll continue to use 1) reason, 2) emotion, and 3) bidirectional feedback between the two. It's always helpful to know how others speak in their silos though in case I need to translate between fields. Thanks.

I felt better about not having heard of this before after seeing this in the wikipedia entry for conation:

"The term conation is no longer widely known—it is in "The 1,000 Most Obscure Words in the English Language", defined as "the area of one's active mentality that has to do with desire, volition, and striving", but a closer look turns up several references to conation as the third faculty of the mind."

One down, 999 more to discover! ; )

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