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Psychologists attempting to apply rigorous scientific methodology to the study of such phenomena as mental imagery, hallucinations, dreaming, and in general, conscious processes face a major challenge: The most direct account available of the private events occurring in a person's mind is his or her own subjective report. But, unfortunately, subjective reports are difficult to objectively verify and introspection is far from an unbiased and direct process of observation. There are two strategies likely to increase our confidence in the reliability of subjective reports: 1) use highly trained (and in the context of dream research, lucid) subjects who are skillful reporters. 2) use the psychophysiological approach, which makes use of the fact that the convergent agreement of physiological measures and subjective reports provides a degree of validation to the latter (Stoyva and Kamiya, 1968).
Indeed, the psychophysiological approach was responsible for the Golden Age of dream research in the decades following the discovery of REM sleep (Aserinsky and Kleitman, 1953) and the subsequent association of REM with dreaming (Dement and Kleitman, 1957). Although the psychophysiological paradigm of dream research yielded an abundant harvest for many years (see Arkin, Antrobus & Ellman, 1978), it possessed a fatal flaw: as long as the subjects are non-lucid, the researcher has no way of making certain that the subjects will dream about what the researcher might like to study. Pre-sleep manipulations producing reliable effects on dream content have not been highly successful (Tart, 1988). One can only wait and hope that eventually a dream report will turn up what one is looking for. This is really no better than a shot-in-the-dark approach and some researchers have been calling for abandoning the psychophysiological method in favor of a purely psychological approach. An influential researcher has written that "...psychophysiological correlation research now appears to offer such a low rate of return for effort expended as not to be a wise place for dream psychology to continue to commit much of its limited resources" (Foulkes, 1981, p. 249). This conclusion may well be justified, but only insofar as it refers to the psychophysiological approach as traditionally practiced, using non-lucid subjects. The use of lucid dreamers overcomes the basic difficulty of the old methodology, and may revitalize the psychophysiological approach to dream research.
The fact that lucid dreamers can remember to perform predetermined actions and signal to the laboratory suggested to LaBerge (1980a) a new paradigm for dream research: Lucid dreamers, he proposed, "could carry out diverse dream experiments marking the exact time of particular dream events, allowing the derivation of precise psychophysiological correlations and the methodical testing of hypotheses" (LaBerge, Nagel, Dement, & Zarcone, 1981, p. 727). This strategy has been put into practice by the Stanford group in a number of studies summarized below.
How long do dreams take? This question has intrigued humanity for many centuries. A traditional answer was that dreams take very little or no time at all, as in the case of Maury's famous dream in which he had somehow gotten mixed up in a long series of adventures during the French Revolution, finally losing his head on the guillotine, at which point he awoke to find the headboard had fallen on his neck. He supposed, therefore that the lengthy dream had been produced in a flash by the painful stimulus. The idea that dreams occur in the moment of awakening has found supporters over the years (e.g., Hall,1981).
We have straightforwardly approached the problem of dream time by asking subjects to estimate ten second intervals (by counting, "one thousand and one, one thousand and two, etc.") during their lucid dreams. Signals marking the beginning and end of the subjective intervals allowed comparison with objective time. In all cases, time estimates during the lucid dreams were very close to the actual time between signals (LaBerge, 1980a, 1985). However, this finding does not rule out the possibility of time distortion effects under some circumstances.
The data reported by LaBerge, Nagel, Dement, and Zarcone (1981) and LaBerge, Nagel, Taylor, Dement, and Zarcone (1981) indicate that there is a very direct and reliable relationship between gaze shift reported in lucid dreams and the direction of polygraphically recorded eye movements. The results obtained for lucid dreams (see also Dane, 1984; Fenwick et al., 1984; Hearne, 1978; Ogilvie, Hunt, Tyson, Lucescu, & Jeakins, 1982) are much stronger than the generally weak correlations obtained by previous investigators testing the hypothesis that the dreamer's eyes move with his or her hallucinated dream gaze, who had to rely on the chance occurrence of a highly recognizable eye-movement pattern that was readily matchable to the subject's reported dream activity (e.g. Roffwarg, Dement, Muzio, & Fisher, 1962).
LaBerge (1986) has carried out related experiments in which two subjects tracked the tip of their fingers moving slowly left to right during four conditions: 1) awake, eyes open; 2) awake, eyes closed mental imagery; 3) lucid dreaming; and 4) imagination ("dream eyes closed") during lucid dreaming. The subjects showed saccadic eye movements in the two imagination conditions (2 and 4), and smooth tracking eye movements during dreamed or actual tracking (conditions 1 and 3).
In another study, LaBerge and Dement (1982a) demonstrated the possibility of voluntary control of respiration during lucid dreaming. They recorded three lucid dreamers who were asked to either breathe rapidly or to hold their breath (in their lucid dreams), marking the interval of altered respiration with eye movement signals. The subjects reported successfully carrying out the agreed-upon tasks a total of nine times, and in every case, a judge was able to correctly predict on the basis of the polygraph recordings which of the two patterns had been executed (binomial test, p < .002).
lucidity
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