[From Bill Powers (2004.07.31.0802 MDT)]
I was looking at a picture from the rover Spirit (I give in) as it nears
the end of its climb to the top of a rock outcrop on West Spur in the
Columbia Hills of Mars. Suddenly I realized that I was attending
consciously to several levels of perception at the same time. The lowest
level was about the size of a pixel, and in fact I could see the fine
grid formed by the elements on the screen. In the full-screen picture, at
800 x 600, there were about 480,000 pixels visible, and I could see them
wherever I looked. They were patches of varying shades of gray, 16 levels
with the 4-bit coding that was used. Bright and dark – intensity. And
there were shadings as well, making surfaces, lines, edges, corners –
sensation level? And then, of course, there were rock configurations of
all sizes, from tiny pebbbles to medium sized shapes to whole outcrops,
with the distant horizon visible beyond the shoulder of the large
outcrop. Check it out:
http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040730a/2NN203EFF80CYL00P1746L000M1-A204R1.jpg
What hit me was that I was consciously observing perceptions
at these different levels. Clearly, there are far too many pixels in the
picture to make it all the way up to the cortex. I was attending, at the
intensity level, to the lowest-level maps that exist in the brain, not
cortical signals. At the sensation level (shading, edge, etc), there were
fewer elements to attend to, so it’s conceivable that they might be
perceived at a higher level in the brain. And the number of perceptions
of rocks, bumps, hollows, outcrops, and horizons was even smaller,
countable, so that might allow for an even higher level of processing in
the brain. Then, of course, there were the even higher-order perceptions,
such as “Hey, this is a picture from a camera on
Mars!”
It seems perfectly clear, today, that the brain is an interface between
awareness and the world outside the brain. The whole brain, not
just the higher regions of it. Awareness knows what the brain delivers to
it, and it knows this at every level of the nervous system. The interface
is three-dimensional, not a single flat layer like a TV screen. We see
consciously all the levels of perceptual signals at once, right there in
the “display,” from intensities to system concepts. This is why
the world looks to us the way it does. The reality and vividness of it
comes from the fact that we are directly aware of the lowest level of
neural signals where everything is drowned in detail – but superimposed
on that is the next level where sensations take on identities, and
superimposed on that are the groupings we call objects (in the visual
modality), which in turn underlie all the other levels of perception. And
they are all right there in the visual picture, not hidden somewhere
behind the eyes inside the head. All the levels are open to conscious
inspection all of the time, in the world that appears to
awareness.
Maybe this whole shebang exists as a package somewhere in the higher
levels of the brain, but it seems to me that there simply isn’t room for
it there. The whole brain is needed to explain experience at all the
levels, and this means that awareness is in contact with signals
everywhere in the brain.
This is actually a belated echo of a partial insight I had over 50 years
ago. It suddenly occurred to me back then some time that everything we
need to know about the brain, or at least everything we can understand
and experience about how it works, is right there in front of us all of
the time. The whole problem is to understand what we are looking at.
That’s when I understood what was wrong with the introspectionist
approach: they were looking for something subtle, hidden, mysterious,
hard to see. In fact the answer was in plain sight before their eyes and
filling every other kind of sensory field as well. To ignore that, while
trying to imagine what is going on inside the head, is to miss the entire
show.
So have a look at this magnificent picture, and see how many levels of
perception you can find in it. And it’s not even in color!
Best,
Bill P.