Here is a confession – I asserted, in a recent posting, that consciousness is discrete like the frames of a movie. A regular commenter, Quentin Ruyant, asked for the evidence that this was an accepted consensus in neuroscience. I have found that it is not accepted by some important neuroscientists. It is an old idea, still current but not in a sense ‘established’. It is still the way I view consciousness because that is how it seems to me, but I will be more open minded about it.
One reason the idea of a cyclic mechanism of consciousness appeals to me is that I have experienced it or something like it. I have on several occasions been a passenger in a car at night on a winding road and I have fought falling asleep by keeping my eyes open. This has produced a discrete series of images rather than a smooth vision of the road. This proves nothing but it does make me very comfortable with the idea. I have not heard anyone else describe this effect until I was reviewing again literature about discrete consciousness.
I am not alone in feeling I have experienced the discontinuity. Oliver Sacks says the following:
“There is a rare but dramatic neurological disturbance that a number of my patients have experienced during attacks of migraine, when they may lose the sense of visual continuity and motion and see instead a flickering series of “stills.”
The stills may be clear-cut and sharp, and succeed one another without superimposition or overlap, but more commonly they are somewhat blurred, as with a too-long photographic exposure, and they persist for so long that each is still visible when the next “frame” is seen, and three or four frames, the earlier ones progressively fainter, are apt to be superimposed on each other. While the effect is somewhat like that of a film (albeit an improperly shot and presented one, in which each exposure has been too long to freeze motion completely and the rate of presentation too slow to achieve fusion), it also resembles some of E.J. Marey’s “chronophotographs” of the 1880s, in which one sees a whole array of photographic moments or time frames superimposed on a single plate.
I heard several accounts of such visual effects while working in the late 1960s with a large number of migraine patients, and when I wrote about this in my 1970 book Migraine, I noted that the rate of flickering in these episodes seemed to be between six and twelve per second. There might also be, in cases of migraine delirium, a flickering of kaleidoscopic patterns or hallucinations. (The flickering might then accelerate to restore the appearance of normal motion or of a continuously modulated hallucination.) Finding no good accounts of the phenomenon in the medical literature—perhaps not entirely surprising, for such attacks are brief, rare, and not readily predicted or provoked—I used the term “cinematographic” vision for them; for patients always compared them to films run too slow.”
In his article (here) for the New York Reviews of Books, Sacks gives a history of this idea that is very readable and interesting.
From what I can gather, the main problem with the discrete model of consciousness has to do with EEG measurements and how much of the cyclic nature of the waves is due to eye muscles rather than brain waves. The papers I have been reading have not produced a clear idea of the controversy so I intend to study this further in the future.