Sunday, 20 January 2008

Making up the Mind 5: Voluntary Action and the Brain



Exposition

In chapter 3 of 'Making up the Mind', Chris Frith aims to tell us that we 'do not have privileged access to knowledge about [our] own body.' Here are just some of the phenomena he describes to arrive at this conclusion:


  1. Marc Jeanerod's experiments that demonstrate that, if our arm is hidden from our vision, and if we are asked to move it in order make a pointer move straight ahead on the screen, and if a computer has introduced a distortion into our movement such that the pointer deviates to the right when we move it, then we may take it that we move our arm straight ahead to get the pointer to move straight ahead even when we have had to move it somewhat to the right.

  2. Benjamin Libet's controversial experiment in which someone is asked to lift a finger whenever he or she felt the urge to do so, and to report when they feel this urge. Libet found that a change in brain activity occurred at 500ms before the action, and that the urge was reported at 200ms before the finger was lifted. 'Our experience of making a choice at that moment is therefore an illusion'.

  3. How, if you ask me to grab a target, and if you then subtly move the target when I am trying to grab it, I may automatically adjust the movement of my arm, but may not be aware of doing this. 'your brain notices that the target has moved and your brain alters the movement your hand is making so that you can reach the new target position. And all this can happen without you noticing anything.'

  4. The Roelofs illusion: I sit in the dark; you present a lit dot in a lit frame. Then you show it again but have secretly moved the frame (but not the dot) to the right (relative to me). If asked I say 'The target moved left', but not mention a frame movement. But if you instead you ask me to touch the point where the dot was, I touch the correct point on the screen. 'So [my] hand "knows" that the target has not moved even though you think it has.'

  5. p. 69: 'These observations show that your body can interact with the world perfectly well even though you don't know what your body is doing and also when what you know about the world is wrong. Your brain may be directly connected to your body, but the knowledge that your brain gives you about the state of your body seems to be as indirect as the knowledge it gives you about the outside world.'

  6. Phantom limb phenomena.

  7. Cases of anosognosia.

  8. Anarchic hand syndrome

Critique

To an imaginary critic who says 'But I know what I am trying to do. And I know when I'm doing it', Frith replies '"I know if feels like that ... But this is an illusion"'. He cites Daniel Wegner's book The Illusion of Conscious Will, who proposes that we have 'no direct knowledge of our actions. All we know is that we have the intention to act, and then, a little later, the action occurs. We infer that our intention caused the action.'

On the back cover of Frith's book, the neurologist Ramachandran writes of how 'Making up the Mind is a fascinating guided tour through the elusive interface between mind and brain...' It is the way in which Frith handles this interface which troubles me. For a tacitly homuncular conception of the relation of the person to the brain seems to be inscribed in the very way he describes all of the experiments and results he cites. On this view, we have a conscious personality on the receiving end of the functioning of the brain, and the acting body also on the receiving end of the brain's 'decisions' and 'inferences'. We take it that we are the ones in control of our actions, but actually, da dah, it is the brain. Consciousness, it turns out, may be nothing other than a spandrel. Frith presents his findings as if the conception of the mind as surprisingly uninvolved with the real neurological and physical goings on was something that dropped out of, rather than constrained the description of, the phenomena.

I shall now explain what I mean by this. If I want to know whether someone is aware of some change in their environment, then I might watch them, or I might listen to what they are sincerely saying. Usually, in non-microscopic (as it were) time frames, and with no brain damage, there is little dissociation between the two; that is, they tend to go together. However at times there is a dissocation. Neuropsychologists including Frith have shown themselves to be excellent at finding such interesting dissociations.

If such dissociation was the norm it is perhaps unlikely that we would have the concepts we do. They depend, as Wittgenstein suggests, on a certain regularity in the presentation of facts. Typically however the dissociations are uncommon. There is a 'unity' to our various verbal and non-verbal reactions. What the data under-determine, however, is the decision to call the one set of reactions 'unconscious' when they occur in the absence of the other, and the other set of reactions a function of 'consciousness'. All that we really have are dissociations between verbal and behavioural responses to the world. Nothing in this justifies the conclusion that in the one set of cases only the brain 'knows' things, whereas in the other set of cases it is 'we ourselves' who know things. In both cases, to the extent that talk of knowledge rather than, say, know-how is appropriate, it is we that know or do not know. Sometimes only some of the marks of knowledge are present, and it may be difficult to know what to say. What I know I definitely do not want to say, however, is that in such cases it is only my brain that 'knows'. That mereological fallacy obscures, rather than aptly describes, the facts and the conceptual situation in question.

What is the evidence that Frith subscribes to the homunculus / inner agent view of the relation between mind and brain? For one thing, we have his constant use of phrases like 'you don't know what your body is doing, but your body 'knows' this or that...'. The assumption seems to be that I am something other than my body. Perhaps I am a consciousness sitting somehow behind the brain, awaiting on any signals about the body or world it deigns to pass my way. (p. 70: 'The knowledge that your brain gives you about the state of your body...')

For another, he describes the Libet experiment as showing (p. 67) that 'We think we are making a choice when, in fact, our brain has already made the choice'. But, like, our brain is part of us, surely, not some other merely physiological quasi-agent to which we are hooked up. Further, what qualifies our action as chosen are a range of contextual factors (what I say about it, whether my finger moves with or without external aid, etc.) which have little to do with immediately causal antecedents. Self-directed action is not action behind which an inner self sits as a kind of director. In the relevant sense we are our bodies, we are not (and do not pre-theoretically take ourselves to be) their inner captains.