The Incorporation of Stimuli into Dreams

Almost everybody has a story to tell about dream incorporation - for instance, dreaming about Arctic exploration only to wake up to find that the covers have slipped off and they are freezing cold, or dreaming of bells ringing only to wake up to find that the alarm clock has been clattering for the last few minutes. Are these dreams really triggered by outside stimuli, or are such reports only the outcome of rather memorable coincidences? How frequently are dreams influenced by such stimuli? Dement and Wolpert (1958) verified that external stimuli could indeed be incorporated into dreams during REM sleep. One example they gave is as follows:

S was sleeping on his stomach. His back was uncovered. An eye movement period started and after it had persisted for 10 minutes, cold water was sprayed on his back. Exactly 30 seconds later he was awakened. The first part of the dream involved a rather complex description of acting in a play. Then, 'I was walking behind the leading lady when she suddenly collapsed and water was dripping on her face. I ran over to her and felt water dripping on my back and head. The roof was leaking. I was very puzzled why she fell down and decided some plaster must have fallen on her. I looked up and there was a hole in the roof. I dragged her over to the side of the stage and began pulling the curtains. Just then I woke up.

Dement and his students played recordings of a variety of sound stimuli, such as bugles, as soon as an REM period started. They found that more than 50 per cent of the dreams reported by their subjects had been noticeably affected by the stimuli. The incorporation of stimuli is thus extremely common if not invariable (given that on many occasions the effects of stimulation on dreaming are so idiosyncratic that they are not recognized by the experimenters).

Berger (1963) assessed the effects of meaningful verbal stimuli on dreaming. These stimuli were the names of the subjects' friends (provided by the subjects) that when presented while the subjects were awake had elicited the largest galvanic skin responses (GSRs). Dream incorporation was judged to have taken place on about half of the occasions. Of the 48 dreams that were judged to have been affected by the stimuli there had been 31 incorporations on the basis of assonance alone - for instance, 'Gillian' had been voiced as 'Chilean', 'Jenny' as 'Jemmy', and 'Mike' as 'like'. Only on three occasions had the named individual actually appeared in the dream as themselves.

The orthodox psychoanalytic view of the processes underlying dream incorporation is that they maintain sleep. The all-important notion of 'dream-work' involves an assumption about the function of dreaming (and possibly of consciousness in general) - that is, that the dream is controlling the subject's psychological state, and not the other way round. Thus, internally generated ideas that would otherwise cause the subject to wake up blushing with shame or racked with guilt are transformed by the dream-work into a symbolic code. In the same way, external stimuli become incorporated into dreams in order to reduce their arousing effect.

The experimental evidence does not contradict this view, but nor does it support it very strongly. While dream incorporations can be explained by the psychoanalytic model, it could also be that only stimuli that fail to arouse the brain sufficiently to tip it into wakefulness result in dream incorporation, rather than that the dream incorporation resulting in continued sleeping. Experimental evidence from Bradley and Meddis (1974) shows that the incorporation of stimuli into dreaming is indeed associated with continued sleep rather than awakening. It remains unclear whether the incorporation actually protects sleep, as the Freudian theory would predict, or whether incorporation is the consequence of delayed arousal.