In a recent comment thread I was nattering on about neurology & consciousness, thinking I'd already covered this particular topic on the blog. But I realised I was thinking of one of my "Up & Anti-Up" columns for Kiss Machine magazine. Here is an excerpt from issue # 11
During neuroscience experiments in the 1970s, patients were poked on the arm, and asked to note the exact moment when they became consciousness of the stimulus. Brain activity was recorded. Next, the patients were poked directly on the area of the brain that had previously been stimulated. Astonishingly, the brain pokes were “noticed” significantly later than the arm pokes were. This suggested that the brain was receiving information after it was first perceived, but sending that information back in time to coincide with the moment of stimulus. Too trippy? Yes, it is, and of course a lot of people have perfectly non-spooky ways of explaining this data. But it is interesting that quantum theory has accustomed us to hearing such seemingly paranormal ideas from the mouths of credible scientists.

Daniel C. Dennett, a philosopher of consciousness, chalks up the phenomenon to a “temporal smear.” He explains that there is no fixed point when external events are registered in the mind, but rather consciousness is a process; a multi-track continuum. In his book, Consciousness Explained, he presents a more fluid model of consciousness, in which, “at any point in time there are multiple drafts of narrative fragments at various stages of editing in various places in the brain.”

Dennett also chides us (and his colleagues) for clinging to Cartesian Dualism; the old idea that consciousness resides on some separate special metaphysical plane, distinct from lumpen matter. While most people nowadays agree that the mind is a physical process (materialism), many of us still cling to a model of the Cartesian Theatre, in which our perceptions play like film on a screen, a “functional place of some sort where the items of phenomenology are projected.” But according to Dennett, “there is no such theatre, there is no such audience.” This would still require an entity separate from the system. Rather, he holds that the continuous, multiple narratives running in our brains are all there is to consciousness. Dennett’s extreme materialism is very influential, though many people feel he goes too far, especially in his 1998 article “Quining Qualia,” published in Consciousness in Modern Science, in which he denies the existence of perceptual phenomena. Nonetheless, by strictly adhering to physiology, Dennett confronts us with the idea that consciousness does not give us access to a definable external reality.

- sally mckay 11-13-2006 7:09 pm

Count me in the "no-spooky" camp for the brain-poking results- it does remind me, however of the Pulfrich effect, which can be demonstrated without the use of a hole-saw and pokey-thing.
It's quite strange to be made aware of your senses working in non-real time. Also, a good trivia item- while the Pulfrich effect requires two eyes to see , Pulfrich himself only had one eye, but had the science skillz to know what would happen. (and before Von Bark beats me to the punch, yes, Andre deToth, director of the great 3D vesion of House of Wax only had one eye. Which he poked out, upon seeing the Paris Hilton version)
Wikipedia article here:
but you can see the effect by putting a sunglass lens over one eye, and moving your mouse cursor back and forth in a horizontal line, and watching it move in and out of the screen.
- rob (guest) 11-13-2006 8:35 pm

thanks for the Pulfrich link, Rob. For the record I am in the non-spooky camp as far as time travel goes - but I am completely open to the idea that our mental record of events is not as linear as we might have once thought. Also, perception is not a simple matter of light passing through lenses. The brain does a lot of invention for us in the process (such as extrapolating data and filling in our blind spots), without which we'd likely get very confused. Says V.S. Ramachandran:

One of the most important principles in vision is that it tries to get away with as little processing as it can to get the job done. To economize on visual processing, the brain takes advantage of statistical regularities in the world—such as the fact that contours are generally continuous or that table surfaces are uniform—and these regularities are captured and wired into the machinery of the visual pathways early in visual processing. When you look at your desk, for instance, it seems likely that the visual system extracts information about its edges and creates a mental representation that resembles a cartoon sketch of the table (again, this initial extraction of edges occurs because your brain is mainly interested in regions of change, of abrupt discontinuity, at the edge of the desk, where the information is). The visual system might then apply surface interpolation to "fill in" the color and texture of the table, saying in effect, "Well, there's this grainy stuff here; it must be the same grainy stuff all over." This act of interpolation saves an enormous amout of computation; your brain can avoid the burden of scrutinizing every little section of the desk and can simply employ loose guesswork instead (bearing in mind the distinction between conceptual guesswork [in which you can imagine stuff at will] and perceptual guesswork [such as this "filling in," which we can't consciously control]).

- sally mckay 11-13-2006 9:37 pm

yeah, the cheats that your brain does in vsion are quite disturbing when they are pointed out.
I'm totally with you on the non-linear mental record thing- acts like catching a baseball or being in the Rockettes might as well be taking place in another dimension. The brain itself is pretty slow, how it manages all that real-time stuff is, as you say, trippy.

- rob (guest) 11-14-2006 12:49 am

A co-worker has done original research on the extensive neural processing the occurs in the retina. Greatly oversimplified, this work shows that the retina does focus its attention on edges and other areas of "change" in the received image.

The way to think of the retina is that it's a chunk of brain (during development it migrates from the brain to the eye), that does powerful image processing (it has multiple layers of sophisticated neural networks), and compresses the vast amount of incoming image data (130 M receptors feed 1.2 M nerves) into a much smaller set of "interesting" data that passes down the optic nerve for futher processing in other parts of the brain.
- mark 11-14-2006 12:54 am

my eye is a brain! coooooool.
- sally mckay 11-14-2006 1:20 am

Then I am willing to argue in court that whatever I see is my intellectual property.
- L.M. 11-14-2006 1:35 am

nice! I like that extrapolation.
- sally mckay 11-14-2006 2:39 am

I'll try to flesh out the argument a bit more in case you get busted and have to scrape the bottom of the barrel for your defence team.
- L.M. 11-14-2006 5:17 am

This makes a lot of sense to me. A couple of years ago, my vision started diminishing rapidly, I experienced it first as a loss of the ability to find a cervix during speculum exams. It turned out to be a galloping form of cataracts, and my vision went to 20/100 over a year. After surgery colours were much brighter, and edges were back. I was so surprised, I had always thought of blindness as blackness, but what I experienced was a diminishing ability to perceive edges and distinguish colours. Now cervices are easy to find again, the problem had been the vaginal wall and the cervix are the same colour, edge was the disguishing feature.
- galenagalaxian 11-14-2006 6:16 am

Total blindness isn't blackness, it's the absence of sight. It's very interesting to experience it temporarily (used to happen to me in my teens)

Now I just suffer from night blindness, and a weird lazy vision thing where I will mistake Windex for hairspray if I'm not wearing my glasses, I can see the difference if I try, but I'm just not making the effort (for the record, I don't answer my hairdryer when the phone rings, so I retain the right to laugh when someone else does it)

It's interesting to read about what the brain is filling in, because I'm now pondering all the stuff I don't see.
- L.M. 11-14-2006 6:32 am

The eye has specific neural structures to extract spatial detail (e.g., edges) and temporal detail (e.g., movement of edges). There are specific aspects of visual perception that can be traced back to those structures. Similarly, the details of the structure of the cochlea inform studies of the auditory system. Just as we are learning that perceptions are artifact of neural structures, brain science will reveal that aspects epistomology and metaphysics can be understood by referring to transfer functions of specific neural structures.

Or, at least that's what my brain believes.
- mark 11-14-2006 9:23 am

This wiggs me out.
I like this new wave of optical illusions that would be much harder to show without the computer.
- joester 11-14-2006 11:18 am

I saw a demo of an eye-tracking system that was being developed for flight simulators. The idea was that it was a waste of computer power to render an entire scene in hi-res if it wasn't being looked at. So this thing would just do a pixelly version of everything that wasn't right at the focus of vision, and anything that got looked at was immediately rendered in a higher resolution. I didn't get to try it, but I'm told it was very effective.
- rob (guest) 11-14-2006 5:28 pm

The color castle illusion is an example of the retina extracting differences and sending those along. (As an example of convergent design, the first step in MPEG is extracting differences between frames.)

Moving the eye resets the differencing networks, ending the apparent color. The passage of time (with a stationary eye) does the same thing, gradually.
- mark 11-14-2006 6:31 pm

Thanks Mark. While I've reading a bunch of quantum physics for dummies, I've been grappling with the amount of information about the structure of our world that we simply cannot perceive. Now I'm struggling to grasp the amount of information in my eye, that I can't perceive. grrr.
- sally mckay 11-15-2006 7:20 pm


- L.M. 11-15-2006 7:51 pm

my first science project for school was "The Flashlight." I took one apart and taped the bits to bristol board. My second science project was "Phrenology" which got me a much better mark.
- sally mckay 11-15-2006 9:58 pm