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…