|
The following is a study used lucid dreamers to determine the
subjective measurement of time in dreams - by Daniel Erlacher and
Michael
Schredl from Germany.
Time required for motor activity in lucid
dreams
Daniel Erlacher - Institute for Sport and
Sport Science, University of Heidelberg, Germany
Michael Schredl - Sleep laboratory,
Central Institute of Mental Health, Mannheim, Germany
Summary
The present study investigated the
relationship between the required time for specific tasks (counting
and performing squats) in lucid dreams and in the waking state.
Five proficient lucid dreamers (26-34 years old, M = 29.8, SD =
3.0; one woman and four men) participated in this study. The
results showed that the time needed for counting in a lucid dream
is comparable to the time needed for counting in wakefulness, but
motor activities required more time in lucid dreams than in the
waking state.
Introduction
The relationship between subjectively
estimated time in dreams and real time has intrigued scientists for
centuries (cf. Hall, 1981). Maury (1861) reported a long and
intense dream about the French revolution which ended with the
dreamer in the guillotine and the sleeper waking up with a piece of
his wooden bed top having fallen on his neck. Because of the
logical line of dream action, Maury (1861) hypothesized that the
dream was generated backwards by the arousing stimulus. Nowadays,
the hypothesis is widely accepted that the subjectively experienced
time in dreams corresponds with the actual time (overview: Schredl,
2000). This relationship was first experimentally demonstrated by
Dement and Kleitman (1957). In this study, the participants were
awakened in a random order either after 5 or 15 minutes of REM
sleep. After awakening, participants were asked to estimate whether
the elapsed sleep interval was 5 or 15 minutes. From 111
awakenings, 83 % judgments were correct. Furthermore, the elapsed
time of the REM period correlated with the length of the dream
report (from r=.40 to r=.71). The latter findings were replicated
by Glaubman and Lewin (1977), as well as by Hobson and Stickgold
(1995). Rosenlicht, Maloney, and Freiberg (1994) found only small
differences between time of REM sleep and the reported length of
dreams. Overall, these studies support the idea that dreams take
the same amount of time the actions would take in waking.
Lucid dreams might be particularly
applicable to study time intervals in dreams, because lucid
dreamers are able of executing prearranged tasks in their lucid
dreams and mark the beginning and the end of the task with eye
signals that can be measured objectively by electrooculogram (EOG)
recording (cf. Erlacher, Schredl, & LaBerge, 2003). The term
“lucid dream” designates a dream in which the dreamer,
while dreaming, is aware that she or he is dreaming and she or he
can consciously influence the action in the dream (Tholey &
Utecht, 1997; LaBerge, 1985). In a pilot study, LaBerge (1985)
showed that time intervals for counting from one to ten in lucid
dreams (by counting from one-thousand-and-one to
one-thousand-and-ten) are close to the time intervals for counting
during wakefulness.
We hypothesized, that there is no
difference between the time needed for counting or performing a
motor activity in a lucid dream and the time needed for the same
activities performed in the waking state.
more after the jump
Methods
The participants were five lucid dreamers
(26-34 years old, M=29.8, SD=3.0; one woman and four men). The four
men participated in previous studies and the woman was recruited by
an internet page (http://klartraum.de) about lucid dreaming
provided by the first author. All participants had lucid dreams for
many years ranging from 30 to 1,000 lucid dreams a year and were
familiar with the method of signaling out of lucid dreams by means
of characteristic, predetermined eye movements.
The experimental protocol for the lucid
dream task was as follows: (1) the lucid dreamers had to stand up
in their lucid dreams, (2) they had to count from twenty-one to
twenty-five, (3) then they had to perform ten squats (deep knee
bends), and (4) finally, they had to count again from twenty-one to
twenty-five. The lucid dreamers were instructed to mark the
following events by left-right-left-right eye movements: the onset
of lucidity, the beginning of each sequence (1-4) and the end of
the lucid dream task. After a maximum of two successful tasks in
one lucid dream, the participants had to wake themselves by the
technique of focusing a fixed spot in the lucid dream described by
Tholey (1983) and report a complete and precise dream immediately.
The participants spent two to four
nonconsecutive nights in a sleep laboratory. Sleep was recorded by
means of the following standard procedures: EEG (C3-A2, C4-A1)
Electrooculogram (EOG), submental EMG and ECG. Prior to the lab
night, the participants were asked to carry out the lucid dream
task in the waking state (including eye signaling measured by EOG
recording). Participants were instructed to carry out the task in
their lucid dreams exactly in the same way as they performed the
task in wakefulness.
In 15 nights, the participants succeeded
in 11 lucid dreams to complete the lucid dream task 14 times. The
participants completed the lucid dream task in different number of
times. In three lucid dreams, the task was accomplished twice. Two
intervals of counting and three intervals of performing squats were
excluded from further analysis because the dreamer wasn’t
able to follow the lucid dream protocol exactly. For the counting
and the squatting intervals, the duration between the two
left-right-left-right eye movements were determined and mean values
for each participant were computed. For statistical analysis,
two-sided t-tests for dependent samples were used to compare the
durations of the counting and squatting intervals in the lucid
dream and in the waking state.
Results
Mean durations and standard deviations for
the counting and the squatting intervals are depicted in Table 1.
No differences in the durations between counting in lucid dreams
and in wakefulness were found for the first counting interval (d =
0.07, power = 0.07; t(4) = .15; p = .89) and the second counting
interval (d = 0.26, power = 0.11; t(3) = .53; p = .64). However, a
significant difference in the time duration was found for
performing squats interval (d = 1.58, power = 0.89; t(4) = 3.54; p
= .02).
Discussion
The study replicates the finding of
LaBerge’s (1985) pilot study, that time intervals for
counting were quite similar in lucid dreams and in wakefulness but
performing squats required 44.5 % more time in lucid dreams than in
the waking state. However, the second counting interval had an
effect size d = .26, which is considered by Cohen (1988) as a small
to medium effect size. Given to the small number of participants
the power of the test was too low to detect a statistical
significant difference. In contrast, the effect size for the
squatting interval was large (d = 1.58), demonstrating that there
is a difference between the required time needed to perform squats
and to count in a lucid dream.
A methodological issue in the present
study is that the duration for the motor activity task was longer
than for the counting task, therefore it might be possible that, in
general, longer tasks cause more of a disproportionate time error
than short tasks. To clarify, if longer task yield different
durations in lucid dreams and in wakefulness, in further studies,
different time intervals (e.g., counting 10 to 60 seconds) should
be examined. Furthermore, subsequent studies should investigate
what kind of factors causes the different time intervals by using
tasks with different complexities (e.g., simple vs. complex
movements).
Even though the participants were
instructed to carry out the squats in the same way as in the waking
state, it is possible that the subjective time for the participants
was different. To test this hypothesis in further studies,
participants should be asked about the subjectively elapsed time
they experienced in their lucid dreams (like Moiseeva, 1975).
To conclude, the present findings, on one
hand support the hypothesis of a correspondence between time
durations in lucid dreams and in the waking state. On the other
hand, the findings also demonstrate that motor activities, like
performing squats, require more time in lucid dreams than in
wakefulness. In future studies, different time intervals, different
activities, and the generalizability of the present results to
dreaming in general should be studied.
References
* Cohen, J. (1988) Statistical power
analysis for the behavioral sciences. Hillsdale, NJ: Erlbaum.
* Dement, W., & Kleitman, N. (1957)
The relation of eye movements during sleep to dream activity: an
objective method for the study of dreaming. Journal of Experimental
Psychology, 53, 339-346.
* Erlacher, D., Schredl, M., &
LaBerge, S. (2003) Motor area activation during dreamed hand
clenching: a pilot study on EEG alpha band. Sleep and Hypnosis, 5,
182-187.
* Glaubman, H., & Lewin, I. (1977) REM
and dreaming. Perceptual and Motor Skills, 44, 929-930.
* Hall, C. S. (1981) Do we dream during
sleep? Evidence for the Goblot hypothesis. Perceptual and Motor
Skills, 53, 239-246.
* Hobson, J. A., & Stickgold, R.
(1995) The conscious state paradigm: a neurocognitive approach to
waking, sleeping, and dreaming. In M. S. Gazzaniga (Ed.), The
cognitive neurosciences. Cambridge: MIT Press. Pp 1373-1389.
* LaBerge, S. (1985) Lucid dreaming. Los
Angeles, CA: Tarcher.
* Maury, A. (1861) Le sommeil et les
reves. Paris: Didier.
* Moiseeva, N. I. (1975) The
characteristics of EEG activity and the subjective estimation of
time during dreams of different structure. Electroencephalography
and Clinical Neurophysiology, 38, 569-577.
* Rosenlicht, N., Maloney, T., &
Freiberg, I. (1994) Dream report length is more dependent on
arousal level than prior REM duration. Brain Research Bulletin, 34,
99-101.
* Schredl, M. (2000) Body-mind
interaction: dream content and REM sleep physiology. North American
Journal of Psychology, 2, 59-70.
* Tholey, P. (1983) Relation between dream
content and eye movements tested by lucid dreams. Perceptual and
Motor Skills, 56, 875-878.
* Tholey, P., & Utecht, K. (1997)
Schöpferisch Träumen. Der Klartraum als Lebenshilfe (3.
ed.). Eschborn: Klotz. |
Consciousness 
