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These foregoing developmental stages refer to how children think about dreams when they are awake. While asleep and dreaming, children, and also adults, tend to remain at the first stage ¬ implicitly assuming that the dream events are external reality. Out-of-body experiences, with a contradictory mixture of material and mental (external and internal), may provide examples of the second stage (LaBerge, Levitan, Brylowski & Dement, 1988). In the fully lucid dream, the dreamer attains the third stage, realizing that the dream world is distinct from the physical world.
Foulkes (1982, 1985) has emphasised the idea that the growth of mind whether dreaming or awake shows parallel degrees of development: "...there are 'stages' of dream development which individual children reliably pass through one after the other, and that the precise age at which they reach a new stage is at least partially predictable from independent measures of their waking mental development." (1985, p. 137)
Lucid dreaming represents in this view what ought to be a normal ability in adults. If this is correct, why are lucid dreams so rare, especially in cases such as nightmares, where lucidity should be extremely helpful and rewarding? I think a possible answer can be seen by comparing lucid dreaming with another cognitive skill -- language. All normal adults speak and understand at least one language. But how many would do so if they were never taught? Unfortunately, in this culture, with few exceptions, we are not taught to dream.
LaBerge (1980b) has demonstrated that lucid dreaming is a learnable skill and there are a variety of techniques available for inducing lucid dreams (LaBerge, 1985; Price & Cohen, 1988). The Stanford group has experimented with methods for helping dreamers to realize that they are dreaming by means of external cues applied during REM sleep, which if incorporated into dreams, can remind dreamers that they are dreaming (LaBerge, 1980a). They have tested a variety of stimuli, including tape recordings of the phrase "This is a dream," (LaBerge, Owens, Nagel & Dement, 1981) conditioned tactile stimuli, (Rich, 1985) olfactory stimuli, (LaBerge, Brylowski & Levitan, 1986) and light (LaBerge, Levitan, Rich & Dement, 1988). The most promising results so far have been with light stimuli.
The psychophysiological studies reviewed above all support the following picture: During REM dreaming, the events we experience (or seem to) are the results of patterns of CNS activity that produce in turn effects on our ANS and bodies to some extent modified by the specific conditions of active sleep, but still homomorphic to the effects that would occur if we were actually to experience the corresponding events while awake.
This conclusion may need further qualification and explanation. Although the events we appear to perceive in dreams are illusory, our feelings in response to dream content are real. Indeed, most of the events we experience in dreams are real; when we experience feelings, say, anxiety or ecstasy, in dreams, we really do feel anxious or ecstatic at the time. When we think in dreams, we really do think (whether clearly or not is another matter). If we think in our dreams that Monday comes before Sunday, it is not the case, as some philosophers (e.g., Malcolm, 1959) assert, that we have only dreamed we thought; we may have thought incorrectly (to the usual way of thinking), but thought nonetheless.
If we were to vividly imagine a detailed sequence of movements, say, walking around the room, it is probable that motor areas of the brain would be activated in the same pattern as involved in actually walking. However, they would presumably be less activated than when walking. Otherwise, what would prevent us from actually walking when we imagined doing so?
In REM sleep there is a spinal paralysis which causes the muscles of locomotion and vocalization to fail to completely execute the action orders programmed by the brain. Thus, in REM, unlike the waking state, there is no impediment to the brain issuing sequences of motor commands at normal levels of activation, and this probably contributes to the experienced reality of dreamed action.
As for the afferent side of the equation, there is a great deal of evidence suggesting that imagery uses the same neural systems as perception in the corresponding sensory mode (see for example, Farah (1988) and Finke (1980). In this view, the essential difference between a perception and a corresponding image is how the identical neural system acquires sufficient activation to produce a conscious experience. In the case of perception, neural excitation (and the resultant experience) is generated by external input, driving activation of the particular schema to-be-perceived in a largely bottom-up process. In the case of imagining (likewise, hallucinating, or dreaming) the experienced image is generated internally by top-down processes activating the appropriate neural network (schema).
Imaginations and perceptions are normally distinguishable by the fact that images are usually much less vivid than perceptions. Normally, perceptions seem real and images seem -- imaginary. How real something appears depends mainly on its relative vividness and experienced vividness is probably a function of intensity of neural activation. Thus, we may conjecture that images usually involve a lesser degree of neural activation than the corresponding perceptions, and this results in a lesser degree of experiential reality for imagination. At least two factors contribute to this state of affairs: one is that while we are awake sensory input produces much higher levels of activation than imaginary input. Imagination interferes with perception in the same modality (Perky, 1910; Segal, 1971) and we may suppose the reverse is true as well. Another more speculative factor favoring perceptual processes over imagination in the waking state is the existence of a neural system to inhibit the activation (vividness) of memory images while perception is active. Evolutionary considerations make such a system likely; it would obviously be extremely maladaptive for an organism to mistake a current perceptual image of a predator for the memory of one (LaBerge, 1985). Mandell (1980) has implicated serotonergic neurons as part of a system that normally inhibits vivid images (hallucinations), but is itself inhibited in REM sleep, allowing dreamed perceptions (i.e., images) to appear as vividly real as perceptions. In REM, also, sensory input is actively suppressed preventing competition from perceptual processes.
Perhaps this explains in part why we are so inclined to mistake our dreams for reality: To the functional systems of neuronal activity that construct our experiential world (model), dreaming of perceiving or doing something is equivalent to actually perceiving or doing it.
lucidity
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