> Eliezer S. Yudkowsky
>> Robert J. Bradbury
>> Given the amount of processing power that the brain has, it seems
>> to me that a *huge* amount of stuff is thought about that we are
>> never aware of.
>I disagree. [. . .] There's no "unconsciousness" capable of independent
>The discipline of
>self-awareness occurs first by learning to admit the things lurking in
>the corners of your mind; second by studying the evolutionary origin of
>our conscious motives; not, at any point, by bringing unconscious
>cognition into consciousness.
The existence of sophisticated unconscious cognition certainly is doubtful. Of course, there is a fair amount of literature on unconscious perception and processing which suggests that such activity does have a not insubstantial effect on behavior. Merikle and Daneman (1998), for example, find that unconsciously-perceived stimuli can have an even greater effect on some behavior than consciously-perceived stimuli. Unconsciously-perceived information---in contrast to consciously-perceived information---tends to be superficial and stimulant of automatic reactions. Nevertheless we are unaware of the exact channels by which this reaches consciousness.
There is also the notorious "hidden observer" phenomenon in hypnosis (where a subject's attention appears to divide so that consciousness remains with only one division while conscious-style processing continues in both), which is admittedly sometimes disputed and still under investigation. Hypnosis has produced other examples of "divided consciousness" (all of which are of course still being studied).
So probably much or all of unconscious processing is of a lower or at least qualitatively different form as compared to conscious processing. Some of that huge amount of stuff of which we are not aware is the constituent processes of awareness itself. Some may not contribute directly to awareness; and some (like autonomic housekeeping) in general remains out of consciousness. So while we might not find whole conversations being conducted beneath our awareness it should be interesting to catch the fragments of thoughts for insight into our perception and behavior. Our concepts of all this are far from complete.
Merikle, Philip M. | Daneman, Meredyth. 1998. Psychological Investigation of Unconscious Perception. _Journal of Consciousness Studies_ 5: 5--18. Also available on the Web somewhere.