After reading a bunch of Dennett lately, it was fascinating to read this, by Stanislas Dehaene:

http://www.edge.org/3rd_culture/dehaene09/dehaene09_index.html

In short: Dehaene thinks he’s found the footprints of consciousness in the brain.  He’s got patterns of brain activation that correlate very nicely with when people report that they are aware of a phenomenon.

In some ways it contradicts Dennett’s theory: Dennett spends whole chapters warning people not to find a locus for consciousness, not to expect a Cartesian Theater where things are presented for viewing.  And Dehaene does rather talk as if there were such a theater. 

On the other hand, much of his findings confirm Dennett too.  There isn’t in fact a particular focus of consciousness– he describes it using Dennett’s phrase, “fame in the brain”.  Consciousness turns out to be a kind of wide-ranging excitement; he describes it as a particular item being made available to the whole brain: the visual system is looking at it, auditory stimulus is available, words and meanings are active, it’s there to be talked about or for action to be made.  Things are connecting up, being made available to all the subsystems.

By contrast, subliminal, non-conscious activations percolate through small sections of the brain and die out in a second or so.  Interestingly, they may percolate as far as awakening particular lexical meanings (that is, they go much farther than mere sensations).

Dehaene also agrees with Dennett that consciousness serves us as a sort of Von Neumann computing machine.  Unconscious thought can handle some simple recognition tasks, but for a series of transformations, you need consciousness.  Consciousness lets us focus on something, play with it in the mind, apply a sequence of steps to it. 

The most intriguing part of the article are the claims that they’ve started to identify particular thoughts— e.g. by looking at the pattern of activation they can guess (better than random chance) what number you’re thinking of– or even more remarkably, what image you’re looking at.  If this pans out, it’s going to be huge; it’s going to be a new revolution in science and society.

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