In Fake Barn Country: Color in Dreams and Fiction, they're arguing about whether you dream in color, and can you be mistaken about that. (A bit of a coincidence, since my previous post on color perception was prompted by a thread on Sequential Tart )
The first thing that springs to mind is that nowadays it's probably possible to settle the question of dreaming in color empirically, by doing a PET scan while someone is dreaming.
The second thing is that what Jonathan is proposing (or agreeing with Ernie on) is really quite weird in light of, for instance, what the Damasios have written about color perception, memory, and language use. Normally, seeing, remembering seeing, and imagining seeing all activate the same parts of the brain. Destroy certain of those parts and you not only become incapable of seeing color, you become incapable of even imagining it any more. On the other hand, destroying the parts that let you assign names to colors, or speak words (including but not limited to those for colors) and you can still perceive, remember and compare colors non-verbally. Physiologically, then, dreaming without perception would seem to require that we dream using only the linguistic centers of the brain--i.e. that we dream in sentences, and confabulate the sensations that we seem to recall having in the process of remembering or recounting the dream. Another possibility would be that the visual centers would light up, but only those responsible for black-and-white imagery. That would be strange, but probably testable, although I'm not sure whether our current undertanding is that color vision is seperable from black-and-white vision as far as what the brain does (obviously there are people who lack color receptors in the retina, so they see in black-and-white, but I don't know if PET scans of their brains show any systematic differences from people with normal vision). Either that, or being in a dream state would somehow turn us into Zombies, where the visual parts of the brain would be doing all their usual stuff which when awake leads to perception and memory and sensation, but while asleep is simply neural activity unattached to qualia but generating memories that will have qualia attached if and when we reactivate them. This latter hypothesis does seem to me to be untestable, but also wildly implausible.
So why were people widely convinced prior to the 60's that dreams were never in color? I don't know. Did they really, or was that one of those stupid things like Behaviorism that only an intellectual could believe?
Posted by joshua at May 7, 2004 03:29 AMJoshua, I'm confused about this:
Normally, seeing, remembering seeing, and imagining seeing all activate the same parts of the brain. Destroy certain of those parts and you not only become incapable of seeing color, you become incapable of even imagining it any more.
I don't see why that should pose a threat to my view. My view is that dreaming is exactly like imagining (because it is imagining). So a person with the brain damage you're describing would not be able to imagine in color, which means he would not be able to dream in color. Isn't this the intuitively correct prediction?
Did they really, or was that one of those stupid things like Behaviorism that only an intellectual could believe?
Schwitzgebel's paper, linked in my post, cites a number of psychological studies, as well as references to the widely-held belief in popular magazines. It does seem that ordinary people believed their dreams were in black-and-white.
Posted by: Jonathan at May 7, 2004 05:18 PMMaybe I misunderstood. What I was reacting to was the following:
Jonathan: I think that Ernie's view is correct; dreams are like fictions or imaginings -- I think that we don't actually have sensations or form beliefs in them; we just imagine that we do.
As I understand it, we really do have sensations when we imagine having them, when we remember having them, or when we dream having them, in that the same parts of the brain responsible for having sensations light up in those cases, and the same parts of the brain if destroyed prevent our having them.
As far as Schwitzgebel's paper, I read it, and I'm still dubious as to whether people at the time genuinely remembered (particularly if they were woken up immediately) dreaming in black and white, or whether they believed that people dreamed in black and white they way they believe that the average person uses only 10% of his brain.
Posted by: Joshua at May 8, 2004 08:13 PM