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Monday, September 1, 2008
Brain / Mind ...

Given my interest in brain science and the human mind, I’ve been pondering something about sight perception. One of the more interesting things that brain research and experimental psychology has discovered is that the “mind”, i.e. our conscious awareness, does not directly perceive the nerve signals coming in from our eyes. Sometimes it is tempting for a layman (like myself) to image consciousness as a little person in a room watching a big screen TV with surround sound. The screen would supposedly project a picture of what the eyes see. But the signals that the eyes send us are blinky and flickering, like the frames of a movie film run slowly (given that the neurons need a moment to recharge between firings). This “reality picture” should also be pixelated; it is not continuous, as there are only so many nerves in the back of the eyes. It would be like looking very closely at a picture in a newspaper (or TV screen), and discovering that it’s made up of little dots on a white background (or black background, for TV).

Well, there is no little person with a big-screen TV in our heads. But it does make me think: if we were to perceive the signals from our eyes more-or-less directly, why don’t we notice the flickering or the pixels, i.e. the many dots? You could say that it’s like the way that we ignore the dots or the flickering on a TV screen; the dots are so small and the refresh rate is fast enough to exceed some perception threshold. Well OK, but that’s begging the question. Just why do our minds convert the dots and changing images into a continuous picture?

HOWEVER. Neuroscience shows that we do NOT base our perceptions on the signals coming in from the eyes. Those signals go through a series of “brain maps”, little parts of the brain that abstract something from the incoming signal (through the miracle of parallel distributed data processing). As such, we partake of a series of “mental conclusions” – e.g., shaped like a box, brown, smooth surfaces, white stripe across top surface, resting on table top, etc. As part of this “abstraction” mechanism, we smooth out our perceptions. As such, the flickers and dots from our senses are changed by a conceptualization process, into smooth lines and continuous color patches and such. What our consciousness sees is largely a conceptual creation by the brain.

So, we are aware of a conclusion that a ball is moving through the air at some rate relative to other things in our “visual awareness frame”; we are not seeing and a flickering, pixelated image of that ball (as with the hypothetical homunculus in the little surround-sound brain theater). When something changes in the major themes and trends encapsulated in our sensory data (e.g. brown rabbit now moving southwest instead of northeast, relative speed of rabbit slow but accelerating), then our “awareness” of it changes.

But — despite all this neuroscientific enlightenment, I am still stumped by a paradox. Even if there isn’t a pixel-dot problem and even if there isn’t a flickering problem to conscious perception, due to the amazing things that connectionist data processing systems can do — the question remains, just what takes all of these smoothed-out trends and information conclusions and turns them into the “vivid subjective experience” of our conscious minds? You would think that they would be merely abstract information at this point; information extremely valuable in making behavioral decisions, but seemingly not meant to “paint us a picture”. More like the printed output from a computer program.

Why do we even need to “see paintings”, i.e. have subjective visual experiences? And what would motion blindness be (a brain defect where people only see flickering images, whereby a car coming down the street looks like a movie going too slow)? Is it a failure of the parallelism devices in the brain to completely process and smooth-out the inputs through the information abstraction methods, and thus causing the “subjective conclusion output” to be closer to raw flickering data?

I would guess — and this is merely a SWAG (stupid wild ass guess) — that whatever in the brain sets up “conscious awareness” somehow mixes the raw, flickering nerve “dots” from the eyes with the processed conceptual conclusions (blue, round, moving, shiny, etc.) needed for behavioral decisions. Somehow, both levels of information (actually, many levels of information, given all the different visual processing steps that the brain imposes on sense data) are taken into consideration by whatever it is that triggers conscious awareness. If this merger of visual information levels weren’t happening, we’d only see blinking dots; or we wouldn’t experience anything other than a series of ongoing realizations regarding external realities near our bodies (like an output list that is continually updated as eye signals stream into the visual data processing centers). Mysteriously, however, a central mechanism that causes and utilizes this final blending cannot be identified in the brain. Consciousness seemingly emanates or emerges from the brain as a whole. Maybe even the body as a whole. Maybe even the universe as a whole?

OK, back to ground level. We do know that conscious awareness is NOT needed for a human to respond to what they see. Think about sleepwalking, when a person can walk, avoid obstacles and even drive a car, but not be conscious of what he or she is doing. Obviously the eyes are working just fine in helping the sleepwalking person to do whatever they are doing (similar case for “absence automisms”). Consider also the various experiments in “blindsight”, the ability of a person who is blind because of defects in the visual processing modules in the cortex to yet be unconsciously aware of things that their eyes still see. (Again, remember these are people whose eyes still work, but are blind because their cortex doesn’t process the information; there is obviously an alternate pathway from the eye nerves to the sub-conscious motor decision centers in the brain, one that skips the areas involved in conscious experience).

This paradox (blinking dot pictures versus smooth but abstract descriptions) says to me that consciousness is something more than the electrochemical processes in the brain. It says to me that mental dualism is alive and well, despite the ill repute that Descartes has gained in modern times. But Descartes was wrong about one thing; it’s not because you think that you are; it’s because you see in smooth, continuous ways that your existence is something more than chemistry and force interactions. Better said, the mystery of subjective experience is tied in with “awareness of being”. It reflects the fact that we are set up by nature to know ourselves, and to ultimately know the value of being. (At least on our better, wiser days).

Perhaps in the end, everything is one (i.e., the ultimate nature of the universe is monistic); but that “one” will encompass more than what we now know through science. Hopefully science will catch up someday with what we know about “being” directly through subjective experience. But until then, it’s up to the gurus and artists and dreamers, and the more daring and speculative philosophers, to keep us from denying the most important thing about human life — i.e., our ability to perceive and appreciate the gift of being and being-awareness.

Political PS: A tip of the hat to Barack Obama for his response to the news that McCain’s VP candidate, Sarah Palin, has a pregnant teenage daughter. Obama said that Palin’s family situation shouldn’t be politicized, and reminds us that his own mother was 18 when he was born. Well, I rather doubt that the Democratic forces will let the whole thing pass without getting some digs in, but Obama’s statement was classy. It was a nice, humane moment in what has otherwise been a depressing mud fight.

◊   posted by Jim G @ 8:37 pm      
 
 


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