Monday, 2 September 2013

Consciousness and Free Will

Some time ago, I read a book called My Brain Made Me Do It, in which the author Eliezer Sternberg (at that time an undergraduate in philosophy and pre-med) talked about some implications of neuroscience he found profoundly disturbing. He seemed most upset by the results of some interesting work using functional MRI to track brain activity while test subjects were asked to perform certain tasks.

Subjects were asked to perform a very simple task: press a button when they felt like doing so. The experiment was intended to piece together the sequence in which various mental events take place, and so the subjects were also asked to make a note of exactly when they decided to press the button, by noting the position of a dot moving regularly in a circle on a screen in front of them.

Now, it turns out that the moment the subjects thought they were deciding to press the button was actually quite a few milliseconds later than the fMRI showed activity in the part of the brain where the choice was actually made. In other words, the conscious experience of choosing was considerably later than the choice itself. The author of this book found that very disturbing with respect to free will, because he felt that a choice made some circuit in one’s brain that lies outside of the actual seat of consciousness was not genuinely a free choice. We do not hold people responsible for epileptic fits or other brain phenomena, after all; doesn’t the discovery that none of our choices are conscious completely do away with the notion of personal responsibility?

I wanted to like this book, because it was engagingly written and earnest, but I kept wanting to shout at it because it was based on an unfounded assumption about the role of consciousness, that it’s the seat of autonomy and choice, the place from which the body is controlled, where “we” as individuals ultimately live. That’s not how I understand consciousness at all, based in part upon my reading of books like Marvin Minsky’s Society of Mind and Daniel Dennett’s Consciousness Explained.

We know now that the brain is made up of a whole lot of specialized agents, little programs that are good at doing one thing and one thing only. There’s a bit of your brain optimized for recognizing the letter “Q”, and one for using chopsticks, and another for remembering that gasoline is flammable. Most of these little components are wired up to other components that perform related tasks, so they can share information as needed; your “Q”-recognizer talks to your word readers that recognize words with “Q” in them, letting them know if there’s a “Q” in the visual field, and keeping quiet if there isn’t.

Now, these agents don’t usually have direct connections to other agents if there’s no frequent reason for them to talk to each other. The “Q”-recognizer needs to be linked to your visual cortex, but rarely if ever needs to share information with the part of your brain that knows how to sing the tune to “Happy Birthday”. That’s where consciousness comes in.

Consciousness is just another part of the brain, but its specialized job is to serve as a kind of public bulletin board to which all the other parts of the brain have access, allowing them to share information they wouldn’t normally be able to share. You can see how this works by catching yourself when it doesn’t work. Example: I had just got out of the ground-floor shower (I usually use the shower in our basement), and was thinking about something else (that is, the bulletin board of my consciousness was busy sharing some other kind of information) when I suddenly realized I had just kicked my dirtly clothes into the closet. A habitual behaviour (kicking the dirty clothes down the laundry chute) that usually operates without the need for conscious oversight had encountered a problem, and posted the error message on my bulletin board: “Something went wrong trying to kick dirty laundry down chute.” The instant this was posted, and thus made available to all parts of my brain, two other brain elements immediately made relevant reports: “The laundry chute is located on the ground floor of your parents’ house”, and “You are currently in your own house”. (Yet another brain element added: “Dumbass!”)

You have probably had similar experiences, where you just did something on autopilot that, if you had stopped to think about it consciously, you would have immediately recognized that you were making a mistake. You probably could have avoided the error if you had been consciously paying attention to what you were doing, but consciousness is a limited resource. If your consciousness is busy sharing information about which house you’re in and what dirty-laundry-protocol to follow, it’s probably not sharing information between the part of  your brain that remembers what’s in the fridge and the part that’s trying to plan what to cook for dinner. But all these parts of your brain are still part of you, even if they aren’t always (or ever, even) starring in the spotlight of consciousness.

Yet there is something to the moral intuition that we don’t hold an epileptic morally accountable for the actions triggered by brain events during a seizure. So how do we draw a meaningful moral distinction between those unconscious brain events and the ones for which we are responsible?

I would suggest that the answer lies not in whether or not the decision is a conscious one (because no decisions are truly conscious in themselves, even if they are immediately reported through consciousness), but whether or not the decision could be influenced by the information content of consciousness. Let me demonstrate with two examples.

First, take a deep breath. Actually, it doesn’t matter if you take a deep breath or not. The decision to do so is yours, and you may decide not to, but at a minimum, the idea of taking a deep breath is now posted in your consciousness bulletin board for all the other bits of your brain to see and work on. There is probably a part resisting: “Wait, why should we take a breath just because someone told us to?” Another part is saying, “Breathing deeply once in a while is good for you anyway! Do it!” Lots of other little bits are piping up with various arguments for or against, while your poor motor control brain segment has been on alert for the decision to proceed or abort with Operation Deep Breath since you first saw the sentence. Whatever your decision element decides, you will become conscious of your decision mere milliseconds later as it is posted to the bulletin board.

Now, you can and do breath unconsciously, most of the time in fact. The part of your brain that controls breathing usually doesn’t bother consciousness with it, and doesn’t require any special information from consciousness to keep doing its job. But it can modify its behaviour in response to such information, such as “Don’t inhale now! You’re under water!” The fact that it can be affected by conscious information is what qualifies taking a deep breath as our act, even though it may not always (and usually isn’t) done under conscious control.

Second example: Sneeze, right now. Now, again, it doesn’t matter if you did just happen to sneeze as you were reading this, because odds are that if you did it’s because you already needed to sneeze anyway. Sneezing is, for most people at least, a reflex action that is driven entirely by physiological stimuli, over which the contents of your consciousness have almost no direct influence. Yes, you can take deliberate actions that will indirectly lead to your sneezing (such as inhaling ground pepper or snuff), but the act of will there is “inhale pepper”; the sneeze is at best a consequence of your volitional act, rather than your own act. And yet sneezing is certainly something that takes place using muscles and organs you generally control, and even involves brain events in the very brain whose decisions you are said to be responsible. 

It’s possible, of course, that you’ve trained yourself somehow to establish some neural link between your consciousness and the sneeze reflex, and maybe you can sneeze at will, in which case I’ve just chosen a bad example for you. For me, at least, the sneeze reflex pays no attention to the content of consciousness, and so it would be inappropriate to attach moral blame or praise to me for my “decision” to sneeze, while it might be perfectly appropriate to hold be responsible for a decision to take or not to take a deep breath. 

To me, then, the fact that decision-making may take place pre-consciously does not in any way raise problems for practical free will. It is a mistake to identify ourselves too closely with only the conscious part of our brains. Our minds are the emergent phenomena of complex networks of distinct brain subsystems, not merely some tiny bit that lives in one little corner, pulling the strings.

3 comments:

  1. "No decisions are truly conscious in themselves"
    What do you mean by that?

    ReplyDelete
  2. Well, just that the portion of the brain responsible for the phenomenon of consciousness is not the part that makes decisions. The deciding element (or elements) actually decide a few milliseconds before they register consciously, because it takes a few milliseconds for the neural signal to reach the consciousness bulletin board.

    Mr. Sternberg found it disturbing that a part of our brain has already decided before we consciously decide, but I'm saying that "consciously deciding", in the sense of some little conscious homunculus inside the brain making a choice, is the wrong way to look at it. Consciousness does no deciding; it simply becomes conscious of decisions made elsewhere in the brain. That's at the scale of individual brain elements, though; on a practical level of individual MINDS, of course we make "conscious" decisions.

    ReplyDelete
  3. It just steps back to jump.

    ReplyDelete