Libet and Dennett: Our brains and ourselves.

So. There’s this thing that bugs me whenever consciousness, the self, and free will come up in discussion or readings.

Let me explain using an old experiment by Benjamin Libet. There were two that commonly get talked about, but I’m going to focus on the second. In this study, participants were hooked up to electrodes and asked to watch a turning disc with a dot on it. Whenever they felt like it, they were to lift a finger and note the position of the dot.

What they expected to find was a burst of EEG activity at around the same time the participants made the decision to lift their finger. There’s some timing issues about intention -> motion transmission times, but that’s generally what they expected.

What they found was a burst of activity about 300ms before the participants consciously reported creating the intention to move. There’s a lot of dispute over the experimental setup, since it’s difficult to be sure of fractions of a second with this sort of self-report paradigm. But a lot of the discussion takes the findings as valid.

What does it mean? It seems like the decision to move was made independently of any intention on the part of the participants – their brains decided to move their finger, and only informed them shortly afterwards. It’s created a lot of talk about free will, and how free we are if our decisions are made before we’re aware of making them – if we are in fact subservient to our brains.

Of course we are.

It’s that sort of nonsense that ought to bother monists in general and neuroscientists in particular. There’s this strange insistence in our society, creating by centuries of dualism and the belief in an immortal soul riding a corporeal shell, that we’re somehow divisible from our bodies and brains. Our brains are us. You cannot say our brains have made the decision before we have, since we are our brains. The fact that you weren’t consciously aware of it makes little difference.

Think about when you speak. Unless you’re making an effort to be articulate, words just come out. How often are you consciously aware of each specific word you’re about to use in a sentence? If you’re speaking your native language, not very. This is why second languages often sound halting – because you’re actually having to consciously pick words rather than just letting them come out as appropriate. Speech is a strange thing, in that it’s consciously directed, and you can switch in and out of conscious control, but otherwise it’s largely unconscious. Sort of like driving after you’ve become experienced.

In fact, there’s a lot of evidence that expertise involves the gradual transfer of control to unconscious function. This is true of both physical skills, and to a certain extent knowledge/usage skills. Even something as typical as typing in a password becomes unconscious after while. Think of things where you have the same login but different passwords, one of which you use more. How often do you type in the more frequent password once you’re entered the less frequent username?

I’ll bring this up a lot, but I think Daniel Dennett has some valuable things to say here. He has written about the ‘multiple drafts’ theory of consciousness, in which information is shunted back and forth in parallel between different modules in a very messy, non-linear fashion. He feels Libet’s experiment is folly because it tries to lock down a single linear progression of action from intention to motion, when in fact things are not so straightforward. This combines with another idea of his, that the self is a ‘narrative centre of gravity’. You can’t locate the physical self, any more than you can locate the centre of gravity of a hoop – it exists, mathematically, and it has properties, but there’s nothing physical there. He sees our consciousness and sense of self as a sort of byproduct of complex mental events, a way to make sense of sensory input, mental manipulation of information, and direct output.

It’s a nice theory. I think Libet’s experiment doesn’t fit his critique exactly – people get tied down into timing issues, but as far as I can tell it doesn’t make much of a difference. Libet’s experiment and Dennett’s theory explain a lot about how we can be fooled by various illusions or cognitive errors, as different drafts of the story come together without any conscious direction. The metaphors may get a bit mixed, but it comes down to my initial point. We’re our brains.

People will say ‘my body’s out to get me,’ or ‘my body has a mind of its own.’ Nonsense. You are your body, and you are your mind. You just aren’t aware of it all the time.

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