Why Are so Many Dreams Forgotten?

Dreams are, therefore, peculiarly unmemorable - unless remembered! There are two possible explanations for the difficulty we have in recalling dreams: there is something about the dream itself (its illogicality perhaps) that makes it difficult to remember; or there is something about our physiological state when we first wake up that makes remembering difficult.

There is a problem with investigating the first of these hypotheses, in that the dreams that are remembered are presumably the ones that have a more logical structure. The most chaotic experiences are forgotten. However, of the dreams that are reported, some are more structured ~ have more coherent themes and plots - than others, and waking subjects do not have any more difficulty remembering the more chaotic dreams than the most coherent (Barber, 1966). Incoherence per se therefore should not make a dream impossible to recall. Another hypothesis is that dreams are forgotten because they are repressed. That is, their content arouses anxiety, causing their recall to become unacceptably upsetting. Freud expressed the view that some dreams, but not all, may be forgotten for this reason. (It would of course be inconsistent with his theory, if dreams that have already been rendered 'harmless' by the dream-work during dreaming remain potent sources of anxiety upon awakening.) Goodenough (1978), in a scholarly review of the very technical evidence on this issue, comparing the recall of dreams by different personality types, concludes that while repression may be responsible for the forgetting of some dreams, it is not feasible that it could account for the majority. This is very much in line with the evidence on repression in everyday life - while convincing anecdotal accounts certainly exist, as does some good experimental evidence of repression in the laboratory, the theory remains unconvincing as an explanation of most of what we forget. One obvious example is looking up a telephone number, closing the directory and then being distracted for a moment by someone asking the time. Merely looking at one's watch and giving the right time is usually enough to prevent the accurate recall of an unfamiliar telephone number. Nobody would suggest that repression was at work here.

It seems likely that there is something about the state that we are in while asleep, that prevents memories from being stored in the normal way. Dealing with experiments on sleep learning, amongst other things, the evidence for this proposition will be discussed more fully. The findings indicate that, as might be suspected from common experience, impressions formed during sleep are not retained. Even if people are woken up and asked to learn something, if they go straight back to sleep they are likely to forget the whole episode. Material presented to people during sleep is not remembered unless they are woken up by it, and remain awake for some time. A minimum period of time filled by waking cortical arousal seems essential for the retention of memories.