Qualia seem atomic to introspection, unanalyzable simples—the smell of violets, the shade of blue, the sound of an oboe—but this is clearly an effect of something like the resolution of our discernment machinery.
If our vision were as poorly spatially resolved as our olfaction, when a bird flew by, the sky would suddenly “go all birdish,”—that peculiar, indescribable birdishness that one would experience in the visual presence of birds. And this resolution is variable: music lovers and wine enthusiasts and others can train up their ear and their palate and come to distinguish, introspectively, the combining elements of what used to seem atomic and unanalyzable. David Huron (2006), has done some ingenious work teasing out and explaining the combinations of neuroarchitectonic properties that explain the otherwise ineffable characteristic qualia of scale tones (the way do sounds different from re and mi and so). It turns out that these “qualia” are actually highly structured properties of neural representations. The explanation, needless to say, is ultimately in the medium of spike trains.
But why should the resolution (if that is the right term) be so low? Why should our brains ignore so much detail in the representations to which “we” have “access”? Minsky (1985), Dennett (1991), Norretranders (1999), Metzinger (2003), and others have said that it is the brain’s own access to its own complex internal activities that accounts for the simplicity. This is the brain’s effective user-illusion for itself, in much the way the desktop with its icons and various metaphors (click and drag, highlighted targets, etc.) is an elegantly designed user-illusion for laypeople who don’t need to know how their computers work.
The brain does not have a single internal witness or homunculus, but it does need something like a lingua franca to get the different and semi-independent subsystems to communicate with each other. (For instance, in the Global Neuronal Workplace model[4] of Dehaene et al. (2006), and others, one should not take it for granted that the local meanings of spike train patterns—in the dorsal vision stream, say, or the olfactory bulb—are readily “understood” by all the elements to which some of these signals are broadcast.) I think there is bound to be some important truth in that theme, but it is only part of the story.