The Stability and Variability of Dreaming

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1 Sleep, 1(3): Raven Press, New York The Stability and Variability of Dreaming Milton Kramer and Thomas Roth Dream-Sleep Laboratory, Veterans Administration Hospital. Cincinnati. Ohio Summary: To examine the stability and variability of psychological dreaming, we collected dream content from the end of the first four REM periods of the night for 20 consecutive nights from 14 volunteers, The dreams were scored for characters, activities, and descriptive elements utilizing the Hall-Van de Castle dream content scoring system, We were able to recover an adequate amount of dreaming (76% recall) from our awakenings and to achieve an adequate level of scoring reliability (91% agreement). Mean content was stable, as the mean overall night to night significant correlation of 0.46 reflects, yet variable enough (79% of the variance is unexplained) to be reasonable and manageable (3 to 15 items per night). Adaptation in dream content did occur as reflected (I) in all four second week content correlations being significant and larger than the nonsignificant first week correlations, and (2) in nights 19 and 20 being highly correlated and significant, whereas nights I and 2 were not; nights 10 and II, while nonsignificant, were at an intermediate level. We conclude that dreaming is both a stable and variable phenomenon that shows clear evidence of adaptation across nights. Key Words: Dreams, laboratory-dream content scoring Reliability of dreaming-stability of dreaming-variability of dreaming. The stability and variability of psychological dreaming are of considerable interest to both the dynamic psychotherapist and the sleep scientist. The psychotherapist is concerned with the stability-variability dimension in dreaming, since it is the dimension central to the manner in which he will utilize the dream in treatment. The sleep scientist finds the stability-variability dimension of great moment, since it is the dimension that determines whether dreaming will be the object of further scientific examination. The psychotherapist has assumed in his utilization of the dream that it is both a stable and a variable process. He treats the dream as stable when he utilizes the dream to make diagnostic statements about the dreamer. He treats the dream as variable when he explores the dream in treatment as responsive to some immediate concern or circumstance in the dreamer's life. The psychotherapist, therefore, Accepted for publication March Address reprint requests to Dr. Kramer at Dream-Sleep Laboratory, Veterans Administration Hospital, 3200 Vine Street, Cincinnati, Ohio

2 320 M. KRAMER AND T. ROTH operates with the dream as if it were potentially revelatory of both the trait and the state aspects of personality, i.e., both stable and variable. The sleep scientist is also interested in the stability and variability of the psychological processes that occur during sleep, such as dreaming. Unfortunately, from the perspective of dream psychology, sleep researchers have focused most of their attention on the biology of sleep-its physiology, pharmacology, and chemistry-and have neglected the study of the dream. Nevertheless, whether dreaming is stable or variable or both has considerable implication for our understanding of dreaming. If dreaming is not stable in some sense, then it is random "noise" in the system, and of no scientific interest. Ifit is stable, then dreaming is a regular process that can become the object of study and manipulation and thus is of greater scientific interest. If, in addition, dreaming is variable in any sense, then it takes on system characteristics of even greater interest because it is stable-flexible systems that are apt to participate in significant, i.e., adaptive, processes. An exploration of the stability of dreaming explores its variability as well. As has been done for sleep physiology (Moses et ai., 1972; Feinberg, 1974; Roth et ai., 1977), an exploration of the stability-variability of dreaming would examine: (1) the adequacy of dream measurement (reliability); (2) the level of overall dream stability-variability (content means and standard deviations); (3) the trends in stability across time (adaptation); and (4) the impact on the system of an acute manipulation (first night and last night effects in the laboratory). Data from such a study of dream variability-stability would allow a comparison of the psychology of sleep (dreaming) with the physiology of sleep (sleep stages) from the same or similar points of view. Recognizing the potential value of an exploration of dream stability-variability to both clinicians and researchers, we undertook to study the dream content of subjects across a number of nights. It is essential, if we are to examine the question of dream stability properly, to study enough normal subjects of the same sex, age, and race for a sufficient number of nights in the sleep laboratory, without any other manipulations, to obtain an adequate amount of data to be scored with a reliable dream content measuring device. All of these factors are known to affect dream content, have been discussed by us in other reports (Kramer et ai., 1975), and are appropriately attended to in the design of our study. METHOD We studied 14 normal, white, male college student volunteers between the ages of 20 and 25 for 20 consecutive nights in the sleep laboratory. The subjects reported to the sleep laboratory 1 hr before their normal bedtime. They were prepared for recording by having a central electroencephalographic lead, two electrooculographic leads, and one chin electromyographic lead affixed to their head (Rechtschaffen and Kales, 1968). The subjects then went to bed and were awakened from the end of each of the first four rapid eye movement periods (REMPs) occurring each night to report on what they had been dreaming. The subjects were allowed to sleep as long as they wished, but the night's sleep was Sleep, Vol. I, No.3, 1979

3 STABILITY - VARIABILITY OF DREAMING 321 terminated if the subject entered the fifth REMP before he spontaneously chose to end his night's sleep. The dream reports were tape recorded, transcribed, and coded. They were scored "blindly" and independently by two raters using the Hall-Van de Castle dream content scoring system (Hall and Van de Castle, 1966) for three content categories: characters, activities, and descriptive elements. The category of characters is self-evident. Activities include such things as physical activities, verbal activities, and movement. Descriptive elements include scoring for such things as size, color, and intensity. A score on each content scale for each subject on each night was derived by summing across the dreams of each night for each subject. Means and standard deviations for each scale were calculated for all 14 subjects over all 20 nights as well as for weeks 1 and 2. Pearson product moment correlations were done for each of the three content categories for each successive night pair, transformed and then averaged across the 20 nights. This correlation expressed the predictability of a given content level from night to night. An overall mean correlation of three content category mean correlations was also computed. The mean correlations for each of the three content categories and a mean of the three correlations were computed for weeks 1 and 2. The correlations of nights 7 to 8 and 14 to 15 were not included to avoid repetition in the former and expansion past 2 weeks in the case of the latter. RESULTS Recall The study presents the possibility of collecting some 1,120 dreams (14 subjects x 20 nights x four awakenings per night). Only 1,086 awakenings were made, primarily because of missed first REMPs, i.e., subjects had only three REMPs during some nights. Out of these 1,086 awakenings, 820 dreams were recalled for a dream recall percentage of 76%. Reliability The two judges each scored all of the dreams on the three scales. The exact percentage agreement dream by dream for each content category was for characters, 91%; activities, 93%; and descriptive elements, 89%. The overall percentage agreement was 91 %. Content The means and standard deviations for the three content categories are as follows: total characters, 7 ± 2; total activities, 14 ± 5; and total descriptive elements, 6 ± 2. The means of the three content means and standard deviations are 9 ±' 3. The means and standard deviations for the three content categories for week 1 are as follows: total characters, 7 ± 5; total activities, 11 ± 12; and total descrip- Sleep, Vol. 1, No.3, 1979

4 322 M. KRAMER AND T. ROTH tive elements, 6 ± 6. For week 2, the means and standard deviations are as follows: total characters, 6 ± 7; total activities, 12 ± 13; and total descriptive elements,s ± 7. The averages of the three means and standard deviations for weeks 1 and 2 are the same, 8 ± 8. Correlations The mean night to night correlations for each of the three content categories and the mean of the three are as follows: total characters, 0.40; total activities, 0.51; total descriptive elements, 0.45; and the average of the overall correlations, All the correlations but the one for total characters are significant (p ~ 0.05). For week 1 the correlations were for total characters, 0.26; total activities, 0.25; total descriptive elements, 0.14; and the mean of the three, None of the correlations for week 1 is significant. For week 2, the night to night correlations were for total characters 0.45; total activities, 0.56; total descriptive elements, 0.50; and the mean of the three, All four of these second week correlations are significant (p ~ 0.05). Although they are all larger and significant, the week 2 correlations are not statistically significantly different from week 1 correlations. Acute Effects The mean and standard deviations of the three content categories on each night in the three night pairs are for nights 1 and 2, 8 ± 6 and 6 ± 6; for nights 10 and 11, 6 ± 7 and 10 ± 11; and for nights 19 and 20, 9 ± 12 and 8 ± 8. The correlations for the three night pairs for each content category are in order, i.e., 1-2, 10-11, 19-20, as follows: total characters, 0.45, 0.07, and 0.61; total activities, 0.37, 0.48, and 0.94; and total descriptive elements, -0.05, 0.44, and The mean correlation for each night pair across the three content categories is for nights 1 and 2, 0.05; for nights 10 and 11, 0.30; and for nights 19 and 20, The mean night correlation across content categories is significantly different from the night 1-2 correlation (p < 0.02). DISCUSSION It is evident from even a cursory examination of the results of the present study that the dream is sufficiently stable and variable to satisfy both the clinician and the researcher. It seems worthwhile, however, to describe the implications of the results for the clinician and the researcher and to contrast the present findings on the stability of the psychology of sleep with the previous work on the stability of the physiology of sleep. The clinician finds support from the present results that the dream is stable enough to reflect long range aspects of personality, e.g., an overall mean night to night significant content correlation of 0.46, and yet variable enough to be potentially reflective of more immediate concerns of the dreamer, i.e., some 79% of the night-to-night variance remains unexplained. Such results are congruent with an increasing body of knowledge derived from experimental dream research that Sleep, Vol, I, No.3, 1979

5 STABILITY-VARIABILITY OF DREAMING 323 suggests that dreams are indeed trait and state sensitive in normal and psychopathological conditions (Kramer et ai., 1976a) and functionally related to the waking affective state of the dreamer (Kramer et ai., 1976b; Roth et ai, 1976; Kramer et ai., 1977). The sleep researcher is interested in knowing if the dream can be reliably measured, shows some degree of stability across time, does or does not adapt, and whether it is responsive to manipulation. These basic questions can all be answered in a positive manner. Yet, the interest in dreams has been artistic rather than scientific. Perhaps this is because the comparable results for the physiology of sleep are so much more powerful. A comparison of the variability of sleep physiology and sleep psychology might prove revealing. First, can dreaming be adequately recovered for use? Clearly, we can obtain dream reports in the laboratory at a rate of 76% of awakenings, which is adequate for most purposes. Important psychological differences can be shown with material obtained at this rate, e.g., male-female (Winget et ai., 1972), sick-well (Kramer et ai., 1969), young-old (Winget et ai., 1972), and schizophrenic-depressed (Kramer and Roth, 1973). Not all of these differences can be shown with sleep physiology measures. Second, can dreams be measured as reliably as sleep stages? It has been repeatedly demonstrated that dreams can be reliably measured, and this study simply confirms that fact (Hall and Van de Castle, 1966; Sandler et ai, 1968; Sandler et ai., 1970; Reichers et ai., 1970). Our mean overall percentage agreement of91% is certainly acceptable and comparable to sleep stage scoring reliability (Karacan et ai., 1978). Third, is dream content from night to night as stable as sleep stage physiology? The overall sleep stage predictability night to night using percentage data is 0.44 and using the time data is 0.28 (Roth et ai., 1977). We have two measures that address the question of the stability -variability of dream content. The mean of the overall correlations of 0.46, which is statistically significant, is the most direct expression of the stability of dream content. The standard deviation of the mean of the overall content categories reflects the content variability. In 95% of cases, all content, i.e., characters, activities, and descriptive elements, will vary between 3 and 15 on any given night. This is a reasonable and manageable range. Dream content data are more like time than percentage data and yet the magnitude of the dream content data overall correlation is more like the latter than the former. The stability of dream content across nights is clearly comparable to that of sleep physiology. It has been suggested that the stability of dream content is a function of its story-like nature and the fact that dreams are repeatedly filtered through a recall process in which stable individual differences are known to occur. Examining other story-like productions of the individual,would help to specify whether that apparent stability of dreaming is unique to the dream process or is a function of other psychological processes of the individual. Fourth, there has been a debate in the experimental dream literature about whether dreams show evidence of adaptation across nights (Whitman et al., 1962; Dement et ai., 1965; Hall, 1967; Piccione et ai., 1976). The present results are the Sleep. Vol. I, No.3, 1979

6 324 M. KRAMER AND T. ROTH first clear evidence we have found of adaptation. The week 2 correlations are larger than those in week 1 in all three content categories and overall. None of the week 1 correlations is significant. while all of the week 2 correlations are significant. Fifth and last, can a first night effect be seen in dream data as it has been occasionally reported in sleep physiology studies? We would expect, because of the so-called first night and last night effect, that content would be suppressed on night 1 as compared to night 2 and likewise for night 20 as compared to night 19. This was not the case. However, we did find that night 1 did not predict night 2 as well as night 10 predicted night 11 or night 19 predicted night 20, suggesting a first night effect. The answer here is equivocal. There may be a first night effect, but whether this is apparent or not may depend on how it is measured. We have examined the stability-variability of normal, unmanipulated dreaming. We conclude that it is both a stable and variable phenomenon that shows clear evidence of adaptation across nights. We compared the results of dream stability to those of sleep stage stability and found similar magnitudes. One may prefer to study the psychology of sleep-the dream-or the physiology of sleep-sleep stages-because of taste or interest but clearly not because one is art and the other science. REFERENCES Dement W, Kahn E, and Roffwarg H. The influence of the laboratory situation on the dreams of the experimental subject. J Nerv Ment Dis 140: , Feinberg I. Some observations on the reliability of REM variables. Psychophysiology 11:68-72, Hall C. Representation of the laboratory setting in dreams. J Nerv Ment Dis 144: , Hall C and Van de Castle R. The Content Analysis of Dreams. Appleton-Century-Crofts, New York, Karacan I, Orr W, Roth T, Kramer M, Shurley J, Thornby J, Bingham S, and Salis P. Establishment and implementation of standardized sleep laboratory data collection and scoring procedures. Psychophysiology 15: , Kramer M, Baldridge B, Whitman R, Ornstein P, and Smith-P. An exploration of the manifest dream in schizophrenic and depressed patients. Dis Nerv Syst (Supp\) 30: , Kramer M and Roth T. A comparison of dream content in dream reports of schizophrenic and depressive patient groups. Compr Psychiatry 14: , Kramer M, Winget C, and Roth T. Problems in the definition of the REM dream. In: Levin P and Koella WP (Eds), Sleep Proceedings of Second European Congress on Sleep Research. Karger, Basel, 1975, pp Kramer M, Hlasny R, Jacobs G, and Roth T. Do dreams have meaning? An empirical inquiry. Am J Psychiatry 133: , 1976a. Kramer M, Roth T, and Palmer T. The psychological nature of the REM Dream. I. A comparison of the REM dream report and T.A.T. stories. PsychiatrJ Univ Ottawa 1: , 1976b. Kramer M, Roth T, and Cisco J. The meaningfulness of dreams. In: Koella WP and Levin P (Eds), Sleep Proceedings of Third European Congress on Sleep Research. Karger, Basel, 1977, pp Moses J, Lubin A, Naitoh P, and Johnson L. Reliability of sleep stages: Psychophysiology 9:78-82, Piccione P, Thomas S, Roth T, and Kramer M. Incorporation of the laboratory situation in dreams. Sleep Res 5:120,1976. Rechtschaffen A and Kales A (Eds). A Manual of Standardized Terminology. Techniques and Scoring System for Sleep Stages in Human Subjects. U.S. Public Health Service, U.S. Government Printing Office, Washington D.C., Riechers M, Kramer M, and Trinder J. A replication of the Hall- Van de Castle character scale norms. Psychophysiology 7:328, Roth T, Kramer M, and Arand D. Dreams as a reflection of immediate psychological concern. Sleep Res 5: 122, Sleep. Vol. I. No

7 STABILITY - V ARIABILlTY OF DREAMING 325 Roth T, Kramer M, and Roehrs T. The consistency of sleep measures. In: Koella WP and Levin P (Eds), Sleep Proceedings of Third European Congress on Sleep Research. Karger, Basel pp Sandler L, Kramer M. Fishbein H. and Trinder J. Inter-laboratory reliability of the Hall-Van de Castle character scale. Psychophysiology 6:248, Sandler L. Kramer M, Trinder J, and Fishbein H. Inter-laboratory reliability of the Hall-Van de Castle characters, social interactions, actiyities and emotions scale. Psychophysiology 7:333, Whitman R, Pierce C, Maas J. and Baldridge B. The dreams of the experimental subject. J Nerv Ment Dis 134: , Winget C. Kramer M, and Whitman R: Dreams and demography. Can Psychiatr Assoc J 17: , Sleep. Vol. 1. No

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