Dream a Little Dream

One of the other issues that came up at Miguel’s cogsci talk was that of the empirical testability of the HOT theory. Miguel suggested that we might have the following argument against HOT. Experimental evidence suggests very strongly that the dorsal lateral pre-frontal cortex is likely to be the home of HOTs. David has said several times that if we did not find activity in the DLPFC when we had evidence that there were conscious mental states about this would be very bad for the HOT theory. So t if we think that we have conscious mental states in our dreams and we accept the evidence that shows that the DLPFC is deactivated during REM sleep this would seem to count as evidence against the HOT theory. David seemed to think that there were basically two plausible responses to this argument. One copuld deny that there are conscious mental states during dreaming or one could argue that the HOTs have a summer home that we haven’t found yet. A lot of the discussion centered on whether or not we had any evidence that dreams are conscious in the way we think they are. David argued that we didn’t Miguel that we did.

David’s argument seemed to me to be the following. The evidence we have that dreams are conscious are the reports that people make when they are awake and remembering the dream. But it is equally consistent with this that the dreams were all unconscious and only seem to be conscious when we reflect on them in the morning. Miguel seemed to think that it was obvious that dreams were conscious. I suggested that perhaps the kind of work that Eric does on dreams suggests that our naive views about dreams are wrong. Pete suggested that we had good experimental evidence that dreams were conscious from teh kind of studies where subjects are given instructions of the sort that if they see a flashing object in the dream they should clap five times. During the discussion the phenomenon of lucid dreaming came up and David reported that in lucid dreaming the DLPFC was active and so lucid dreams count as conscious mental states.During REM sleep subjects then can be seen to make clapping motions. But is it clear that this counts as a report in the relevant sense? This activity could be the result of unconscious dreams just as well as the result of conscious dreams. In David’s terminology we can ask whether the clapping is an expression of their mental states or whether it is a report. If it truly counts as a report and there is no activity in the DLPFC then David’s view would be in trouble.

This got me to thinking; how could we devise an actual empirical test of these kinds of issues? Hakwan suggested an interesting conceptual approach earlier which led me to think about binocular rivalry. If you could just have subjects in a scanner looking at  stimuli that are known to induce binocular rivalry without having the subjects do any kind of reporting we could then look at the DLPFC and see if the activity there reliably correlates with the conscious percept. A quick search on this led me to this article which seems to get results that line up with HOT theory very nicely, though with scalp EEG and with a button push which is a confound…

6 thoughts on “Dream a Little Dream

  1. I was surprised that the premise that was rejected was the one that maintain that there are conscious dreams. I thought that everyone would concede that one. I’ll have to do a better job to defend it.
    I am pretty convinced that I have conscious dreams, the best case is the continuum in my experience between my sensation of thirsty in my dreams, where I drink and drink without stopping my thirsty and my feeling of thirsty when I realize that I was dreaming and drink real water, or the fact that sometimes the sound of my clock alarm is incorporated into my dreams. I have had pain in my dreams and other much more pleasant experiences.
    Although maybe it is compatible with having false memories, it seems to me that maintaining that dreams are conscious is more plausible, but I toke it to be relatively uncontroversial and it isn’t.

    Hakwan’s result points in the direction of DLPFC (obviously DLPFC being part of the correlate of consciousness does not prove HOT right) being the home of HOTs. As Richard noted HOTs could have a summer house but as I said that would entail duplication of complicated function (forming HOTs) just for dreaming.

    One possibility that no one considered, and I am not sure how plausible it is, is the following: despite the fact that there is a deactivation of DLPFC, the remaining activity is sufficient for HOTs. This possibility is more plausible for proposal like the one by Hakwan or the one by Uriah Kriegel that for one like David or Richard where the phenomenology depends just on the HOT.

    In his paper ‘Sleep and dreaming’ in ‘The neurology of consciousness’. Tononi noted that one difference between weaken and dreaming consciousness (he also considers that we have conscious experiences during dreams) is:
    “During dreaming there is a prominent reduction of voluntary control, whether of action, thought, or attention, with the exception of lucid dreaming…”. According to him DLFPC has a role in phenomenology which fits with its role in volitional control and self-monitoring.

    One cannot defend that Lucid dreams count as conscious because there is an activation of DLPFC, because what is under dispute is the role of DLPC in consciousness. The non question begging way to proceed would be to defend that lucid dreams are conscious and then show that DLPFC is activated during lucid dreams.
    As far as I know there are no evidence that DLPFC is activated during dreams. In the mentioned paper Tononi says:
    “It is plausible, but not proven, that the deactivation of dorsolateral prefrontal cortex that is generally observed during REM sleep may not occur during lucid dreams.”

  2. The question of consciousness in dreams is very interesting, and I like the idea of testing it by determining whether or not people can report dream experiences while dreaming. But I think the only way this could be done is if the dreaming subject were reporting the experiences to somebody else–that is, there must be interaction between the dreaming subject and another subject within the dream. The experimenter would have to interact with a person as a part of their dream, like in Dreamscape (1984). We have no evidence that this sort of interaction is even possible, so it follows that we have no evidence that consciousness of this sort is present in dreams.

    But, as I suggested in my last sentence, perhaps we can talk about dream consciousness of another sort–perhaps what David Chalmers would call “phenomenal consciousness”–that is, a dreaming subject can have experiential states with qualitative character, but lack the psychological abilities we associate with self-awareness and action. This would have to be an unreportable sort of experience, but which left reportable traces in our memories. But I don’t think we could test for that. We’d have to establish a causal connection between neural activity and phenomenal experience first and then look for it in dreaming subjects. But even if we found the right brain activity occurring in dreaming subjects, we couldn’t be sure that the activity was sufficient for phenomenal experience. And if we didn’t fine the right activity, we still couldn’t be sure that some activity qualified as sufficient for a phenomenal experience. So it seems hopeless.

    What this suggests, I think, is that the very notion of a phenomenal consciousness independent of psychological consciousness is inherently untestable.

  3. Thereare two states of mind i experience from time to time that seem relevant

    1) I was driving along hte other day and suddenly became aware that two streams of thought htat had previously been independant (one had actively wondered about the other without activating it) merged. In this case one was listening to the radio, and wondering about why it wasnt thinking about driving and the other was driving. So i got the odd feeling of both remembering thinking about driving and also remembering wondering why I wasnt thinking about it.

    2) in lucid dreams (which i do a lot) at the end of a dream i can be in a state where the dream is definitly still going on and yet I know i can open my eyes or move my arms etc.
    and when i do that I probably wake up (with some effort). who knows if i move before that point but it seems to me (feels identical) that I have control of some muscles first – like the one that raises my eyebrows. if i can remember it and control the muscles it seems like one could communicate with me in dream…

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