May 21, 2003

Not Master Inside My Own Skull

I'm shaving. I see, out of the corner of my eye, the dog trot into the bathroom. 55 pounds of very white Labrador Retriever ("How do you keep your dog so white?" someone once asked my wife. She said that she felt she had fallen into a laundry commercial, and wanted to reply, "Why, with CLOROX(tm) bleach with brighteners?" Actually, we just let the mud dry and it falls off when she rolls on the carpets). It's truly out of the corner of my eye, so I don't see much detail, but I see the moving of the legs, the wagging of the tail, the floppy ears.

But there's no noise. "Why is the dog so silent?" I wonder. I turn right--and it's not a dog at all. It's just a piece of shaving cream on my right sideburn.

But I saw her. I know I saw here. I know I saw her as much as I see this computer screen right now, or as much as MacBeth saw his dagger of the mind before him..

Last week we went up to watch the lunar eclipse. During totality we saw the dim mottled reddish disk of the eclipsed moon .(But was it really only 1/10,000 - 1/100,000 as bright as the full moon, which is what the photometers tell us? Didn't seem so.) At the end of totality the first direct photons from the limb of the sun hit the limb of the moon, the moon's edge lighted up... and all of a sudden the moon changed from a disk to a ball. It was clearly three dimensional. My knowledge that the moon is a ball had always been indirect, for my sight had always told me that the moon was--as it obviously is--not a ball but a disk: balls, after all--or so my visual cortex tells me--have substantial and predictable variations in brightness across their surfaces as you look at those parts closer to and further from the primary source of illumination. The full moon doesn't have such variations in brightness. (What is that you're saying? That it does? But that at night your rods are neurologically firing at their maximum rate even when they are focused on the dimmest parts of the moon?)

But last week, for half an hour, it did: the moon looked like a ball. Spooky.

Physiological visuality is the obvious place to look if you are looking for an example of unconscious processing--of highly sophisticated acts of information processing... thought... visualization, on emight call it... that are completely inaccessible to the Cartesian ego that cogitos. But it cannot be the only example. Leave completely aside the hormone-firing induced transvaluations of values that occur when you fall in love or first see your child--things that change your aims and goals but not your mind-considered-as-a-tool. How crowded is it inside my skull, really? How much of a captain of my soul can I claim to be?

Posted by DeLong at May 21, 2003 10:12 AM | TrackBack

Comments

The most striking example of unconscious processing is how we process speech and text. It's impossible for anyone who knows English to hear words and not hear them as words.

Sometimes after we've heard someone utter a sentence we can remember exactly the contents of what they said but have next to no recollection of the actual words they used, let alone how those words sounded. The sounds, and even the words, don't get noticed by the 'Cartesian ego' - it just gets the summary report from the speech analysis module of what was said.

This isn't to say that the 'Cartesian ego' has particularly good access to how the non-texty parts of the world look. The checkerboard illusion Brad posted a few weeks ago (Checkershadow "Illusion", April 6) is a pretty stunning demonstration of how much visual processing goes on before we get to conscious cognition.

Posted by: Brian Weatherson on May 21, 2003 10:38 AM

I am somewhat deaf, but compensate by paying attention to the person speaking (I don't lipread exactly, but have found that visual cues help). However, because I spend a fair amount of time with my wife, she occasionally finds it useful to speak to me when I'm not looking in her direction. She gathers no end of amusement from my confident answers that bear no relation to her questions.

But, but I heard her say that...I know it...

Posted by: Martial on May 21, 2003 12:12 PM

I am somewhat deaf, but compensate by paying attention to the person speaking (I don't lipread exactly, but have found that visual cues help). However, because I spend a fair amount of time with my wife, she occasionally finds it useful to speak to me when I'm not looking in her direction. She gathers no end of amusement from my confident answers that bear no relation to her questions.

But, but I heard her say that...I know it...

Posted by: Martial on May 21, 2003 12:17 PM

Why have a dictatorship when you can have a democracy?

Posted by: Jack on May 21, 2003 02:05 PM

this was addressed by VS Ramachandran in one of his Reith Lectures on the brain:

http://www.bbc.co.uk/radio4/reith2003/reith2003_lecture1_transcript.shtml

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A patient I saw not long ago who had been in a car accident, had sustained a head injury and was in a coma for about a couple of weeks. Then he came out of this coma and he was quite intact neurologically when I examined him. But he had one profound delusion - he would look at his mother and say "Doctor, this woman looks exactly like my mother but she isn't, she is an imposter".

Now why would this happen? Now the important thing is this patient who I will call David is completely intact in other respects. Now to understand this disorder, you have to first realise that vision is not a simple process. When you open your eyes in the morning, it's all out there in front of you. It's easy to assume that it's effortless and instantaneous but in fact you have this distorted upside down image in your retina exciting the photoreceptors and the messages then go through the optic nerve to the brain and then they are analysed in thirty different visual areas, in the back of your brain. And then you finally after analysing all the individual features, you identify what you're looking at. Is it your mother, is it a snake, is it a pig, what is it? And that process of identification takes place in a place which we call the fusiform gyrus which as we have seen is damaged in patients with face blindness or prosopognosia.

So once the image is recognised, then the message goes to a structure called the amygdala which is sometimes called the gateway to the limbic system which is the emotional core of your brain, which allows you to gauge the emotional significance of what you are looking at. Is this a predator, is it a lion or a tiger? Is it a prey which I can chase? Is it a mate that I can chase? Or is it my departmental chairman I have to worry about, or is it a stranger who is not important to me, or something utterly trivial like a piece of driftwood? What is it?

Now what's happened in this patient? What we suggest is that maybe what's gone wrong is that the fusiform gyrus and all the visual areas are completely normal in this patient. That's why when he looks at his mother, he says "oh yeah, it looks like my mother", but the wire, to put it crudely, the wire that goes from the amygdala to the limbic system, to the emotional centres, is cut by the accident. So he looks at his mother and he says - "hey, it looks just like my mother, but if it's my mother why is it I don't experience this warm glow of affection (or terror, as the case may be). There's something strange here, this can't possibly be my mother, it's some other strange woman pretending to be my mother". It's the only interpretation that makes sense to his brain given the peculiar disconnection.

Posted by: kenny on May 21, 2003 02:41 PM

Kenny's story also reminds me of an explanation offered for the odd fact that, every year, dozens of humans in orange jackets get mistaken for deer and shot by their fellow humans. It isn't that the victim actually got "morphed" into a deer, like Chaplin becoming a giant chicken in the eyes of the starving prospector in The Gold Rush. Rather, for every object the hunter's eyes light upon, he asks himself "is it a deer? is it a deer?" Eventually, there's a temporary short-circuit in the overloaded "recognition center" and it returns a false positive.

Posted by: Jeffrey Kramer on May 21, 2003 09:59 PM

>>But was it really only 1/10,000 - 1/100,000 as bright as the full moon, which is what the photometers tell us? Didn't seem so

Your pupils contract when you're looking at something bright.

Posted by: dsquared on May 22, 2003 03:58 AM

You know, graphic artists, painters and sketchers, know that if the eye couldn't be bamboozled they'd be unable to make you think that some smudges of paint on a canvas are a beautiful sunset. Go study one of Frederic Church's beautiful landscapes sometime in a gallery if you get the chance. He was a master at it. The paintings are almost hyper-real, but up close you really see how it's the deft application of paint that does it. There is no space beyond the surface of the canvas. Yet your eye insists that it's not only there, it is vast. Stand in front of The Andes Of Ecuador and you can almost feel the high mountain breeze wafting around you.

This is all the artifact of how millions of years of evolution made us. Our senses work just fine, otherwise our kind would not have long endured, but they do not give us the perfect god's eye view either. This is why we periodically test the reality we think we see. In science, and in day to day life, we understand that we have to put what we believe to be true, to test. We are captains of our own souls, to the degree we choose to understand ourselves, and the reality we live in, as best as we can, and act on the understandings we gain accordingly.

Posted by: Bruce Garrett on May 22, 2003 07:39 AM
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