What are dreams like, experientially?
One common view is that dreams are like hallucinations. They involve sensory or sensory-like experiences just as if, or almost as if, you were in the environment you are dreaming you are in. If you dream of being Napoleon on the fields of Waterloo, taking in the sights and sounds, then you have visual and auditory experiences much like Napoleon might have had in the same position (except perhaps irrational, bizarre, or otherwise different in specific content). This is probably the predominant view among dream researchers (e.g., Hobson and Revonsuo).
Another view, less common but intriguing, is that dreams are like imaginings. Dreaming you are Napoleon on the fields of Waterloo is like imagining or "daydreaming" that you're there. The experience isn't sensory but imagistic (e.g., Ichikawa and Sosa).
These views are very different!
For example, look at your hands. Now close your eyes and imagine looking at your hands. Unless you're highly unusual, you will probably agree that the first experience is very different from the second experience. On the hallucination model of dreams, dream experience is more like the first (sensory) experience. On the imagination model, dream experience is more like the second (imagery) experience. On pluralist models, dream experiences are sometimes like the one, sometimes like the other (e.g., Rosen and possibly Windt's nuanced version of the hallucination model). (Unfortunately, proponents of the hallucination model sometimes confusingly talk about dream "imagery".)
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I confess to being tempted to the imagination model. My reason is primarily introspective or immediately retrospective. I sometimes struggle with insomnia and it's not unusual for me to drift in and out of sleep, including lying quietly in bed, eyes closed, allowing myself to drift in daydream, which seems sometimes to merge into sleep, then back into daydream, and my immediately remembered dreams seem not so radically different from my eyes-closed daydream imaginations. (Ichikawa describes similar experiences.)
Another consideration is this: Plausibly, the stability and detail of our ordinary sensory experiences depend to a substantial extent on the stabilizing influence of external inputs. It appears both to match my own experience and to be neurophysiologically plausible that the finely detailed, vivid, sharp structure, of say, visual experience, would be difficult for my brain to sustain without the constraint of a rich flow of input information. (Alva Noë makes a similar point.)
Now, I don't put a lot of stock in these reflections. There's reason to be skeptical of the accuracy of introspective reports in general, and perhaps dream reports in particular, and I'm willing to apply my own skepticism to myself. But by the same token, what is the main evidence on the other side, in favor of the hallucination model? Mainly, again, introspective report. In particular, it's the fact that people often report their dream experiences as having the rich, sensory-like detail that the hallucination model predicts. Of course, we could just take the easy, obvious, pluralist path of saying that everyone is right about their own experiences. But what fun is that?
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In fact, I'm inclined to throw a further wrench in things by drawing a distinction between two types of hallucination: phenomenal and doxastic. I introduced this distinction in a blog post in 2013, after reading Oliver Sacks's Hallucinations.
Consider this description, from page 99 of Hallucinations:
The heavens above me, a night sky spangled with eyes of flame, dissolve into the most overpowering array of colors I have ever seen or imagined; many of the colors are entirely new -- areas of the spectrum which I seem to have hitherto overlooked. The colors do not stand still, but move and flow in every direction; my field of vision is a mosaic of unbelievable complexity. To reproduce an instant of it would involve years of labor, that is, if one were able to reproduce colors of equivalent brilliance and intensity.
Here are two ways in which you might come to believe the above about your experience:
(1.) You might actually have visual experiences of the sort described, including of colors entirely new and previously unimagined and of a complexity that would require years of labor to describe.
Or
(2.) you might shortcut all that and simply arrive straightaway at the belief that you are undergoing or have undergone such an experience -- perhaps with the aid of some unusual visual experiences, but not really of the novelty and complexity described.
If the former, you have phenomenally hallucinated wholly novel colors. If the latter, you have only doxastically hallucinated them. I expect that I'm not the first to suggest such a distinction among types of hallucination, but I haven't yet found a precedent.
Mitchell-Yellin and Fischer suggest that some "near death experiences" might also be doxastic hallucinations of this sort. Did your whole life really flash before your eyes in that split second during an auto accident, or did you only form the belief in that experience without the actual experience itself? It's not very neurophysiologically plausible that someone would experience hundreds or thousands of different memory experiences in 500 milliseconds.
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It seems clear from dream researchers' descriptions of the hallucination model of dreams that they have phenomenal hallucination in mind. But what if dream experiences involve, instead or at least sometimes, doxastic rather than phenomenal hallucinations?
Here, then, is a possibility about dream experience: If I dream I am Napoleon, standing on the fields of Waterloo, I have experiences much like the experiences I have when I merely imagine, in daydream, that I am standing on the fields of Waterloo. But sometimes a doxastic hallucination is added to that imagination: I form the belief that I am having or had rich sensory visual and auditory experience. This doxastic hallucination would explain reports of rich, vivid, detailed sensory-like dream experience without requiring the brain actually to concoct rich, vivid, and detailed visual and auditory experiences.
Indeed, if we go full doxastic hallucination, even the imagination-like experiences would be optional. (Also, if -- following Sosa -- we don't genuinely believe things while dreaming, we could reframe doxastic hallucinations in terms of whatever quasi-belief analogs occur during dreams.)
6 comments:
One argument against the imagination model is that I can't recall ever having mistaken something which I merely imagined for something that actually happened. But I have often woken from a dream and had to figure out that my preceding experiences were just a dream. And on other occasions I've misremembered doing something mundane which I only did in a dream; for example, I was surprised when there are eggs in the fridge because I thought they were all used up, and the best I could figure was that I dreamed using them up.
I think dreams have to be at least partly doxastic hallucination. I recall a dream in which I was Hamlet. It wasn't that I had experiences that were like ones Hamlet might have and inferred I was Hamlet, or that I recited lines from the play. Rather, I was meeting my parents at the airport, and (in the dream) I simply knew as a fact that I was Hamlet.
Thanks for the comment, P.D.! I agree that the easiest, most natural explanation for such confusions between dreams and memories is that dreams and waking experiences have similar phenomenology. But if there's reason to think that dreams and waking experiences have different phenomenology, we can appeal to doxastic hallucination or source monitoring problems as an alternative account. Compare: People sometimes forget whether they saw the keys on the table or only imagined seeing the keys on the table; but still the original visual and imagery experiences are generally held to be pretty phenomenologically different. On whether "knowing" that you're Hamlet is doxastic hallucination: It isn't in the narrow sense of doxastic hallucination I had in mind which concerns believing that you have or had certain experiences; but on a broader sense of "doxastic hallucination", that very much makes sense, and maybe the broader definition has something going for it.
Having had lucid dreams it's clear (to me anyway) that waking and dream experience can be equivalent in phenomenal vividness and in metacognition: you know you're having experiences and where you are when having them. In a lucid dream, you know you're asleep in bed and can consciously evaluate the phenomenal character of colors and other sensations, comparing them to waking experiences. Such dreams really drive home the point that experience is an internal construction and that waking experience is, as Thomas Metzinger once put it, "dreaming at the world" and as Anil Seth likes to say, a "controlled hallucination."
Tom: Yes, that's probably the mainstream, majority view. Is there any chance that you're doxastically hallucinating during those lucid dreams? That is, is there any chance that you believe you have having detailed visual-sensory experiences of, say, a landscape over which you are flying despite not actually having visual-sensory experiences with that kind of detail? Is there any chance that you are saying to yourself, essentially, "what a rich sensory experience I am having of flying!" -- convinced that you are having such an experience -- while in fact your experience is not as rich as that?
Is there any chance that you're doxastically hallucinating right now, that is, merely believing you're having the apparent stream of experience you'd report having? If you say no, how do you justify that claim? Perhaps by asking someone next to you to validate it. But that experience of validation is equally vulnerable to the same objection. Lucid dreams are as real as experience gets but until you've had one it's reasonable to doubt their equivalence to waking experience.
Fair enough that there's in principle no limit to skepticism once the cat is out of the bag. I'd say there would have to be plausible grounds for doubt about the truth of that description of lucid dreams in order for the skeptical possibility of doxastic hallucination to arise. Depending on one's view about the imagination model of dreaming and what kinds of experiences the brain can support without stable input streams, one might think there are grounds for doubt -- though of course both of these are tenuous and theoretical and might feel frail compared to the lived experience of lucid dreaming. For the record, I have occasionally had lucid dreams (though none I recall in several years) and I am nonetheless still tempted by the imagination model and the idea of doxastic hallucination.
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