A Psychophysiological Study of Out-of-the-Body Experiences

This mind boggling experiment done in 1968 points to the fact that the human consciousness is mobile. It does not have to be stationary inside the brain but can move around at will. If this is true the western scientific view of the brain and consciousness needs to be revised.

Researcher: Charles T. Tart Psychology Department, University of California. The experiment was published in the Journal of the American Society for Psychical Research, 1968, vol. 62, no. 1, pp. 3-27.

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Abstract
A young woman (Miss Z) who frequently had spontaneous out body experiences (OBEs) was studied in a sleep laboratory for four nights. She reported several partially out experiences and two full ones. While the physiological data are limited by dependence on her retrospective report in correlating physiological pattern with the experience, it seems as if her out experiences occurred in conjunction with a non-dreaming, non-awake brain wave stage characterized by predominant slowed alpha activity from her brain and no activation of the autonomic nervous system. Two incidents occurring in the laboratory provide suggestive evidence that the out of-the-body experiences had parapsychological concomitants.

Description of Miss Z
Miss Z is a young, unmarried woman in her early twenties, with two years of college education. Her education was temporarily interrupted at the time of this study because of her need to work in order to earn money to continue at college. She is a warm and highly intelligent person, and had great interest in what the study would show. Psychologically, it is extremely difficult to describe Miss Z. My informal observations of her over a period of several months (undoubtedly distorted by the fact that one can never describe one's friends objectively) resulted in a picture of a person who in some ways was quite mature and insightful, and in other ways so extremely disturbed psychologically that at times, when she lost control, she could possibly be diagnosed as schizophrenic.

Miss Z came from a broken home. She recounted a number of instances of apparent parapsychological interaction between her and her parents as well as between her and her foster parents. She had been hospitalized for several weeks for psychiatric treatment about a year prior to the present study. Despite numerous psychological difficulties in her personal life during the several months over which the experiment was carried out, however, Miss Z did not interject her personal difficulties into the experimentation.

Preliminary Experiment
My (Charles Tart's) interest in OBE experiences has two separate facets. On one level, I am interested in such experiences as a unique, psychological experience, possibly related to nocturnal dreaming. On another level, I am interested in the extrasensory aspects of the experience: in some OBE experiences the person reports accurate information about the distant localities he seemed to be at, and such information would apparently have to have been acquired by some form of extrasensory perception. Thus we have a unique psychological experience worthy of study in its own right, as well as an experience that often seems to have parapsychological aspects.

Laboratory Procedure
I (Charles Tart) was able to observe Miss Z in my sleep laboratory for four non-consecutive nights, over a period of approximately two months. The procedure was essentially the same on all nights, and will be described here. Miss Z's electroencephalogram (EEG) was recorded each night.

Recording was continuous through the night on a Grass model VII polygraph, running at a speed of ten millimeters per second. Rapid eye movements (REMs) were recorded by means of a miniature strain gauge, taped over the right eyelid. This technique for recording REMs is described in detail elsewhere (4, 58). Movement of the eye under the closed eyelid distorts the strain gauge and a corresponding electrical output is recorded on the Grass polygraph. This combination of two EEG channels and a REM channel is typical in sleep studies and allows one to discriminate the various stages of sleep, including dreaming sleep.

Basal skin resistance (BSR) was also recorded on the Grass polygraph. Silver-silver chloride electrodes were used, one on the thenar eminence of the palm of the right hand, the other on the right forearm.

The sleep laboratory consisted of two rooms, each lined with acoustic tile for sound attenuation. A large window was between the rooms for viewing, but in this experiment it was covered with a Venetian blind in order that the subject's room could be reasonably dark for sleeping. This blind allowed enough light to come through so that the subject's room was dimly illuminated, but not enough to disturb sleep.

The polygraphs were located in the second room, and the door was kept closed. An intercom system allowed hearing anything the subject said. I monitored the recording equipment throughout the night while the subject slept and kept notes of anything she said or did. Occasionally I dozed during the night, beside the equipment, so possible instances of sleep talking might have been missed.

The subject slept on a comfortable bed just below the observation window. The leads from all electrodes were bound into a common cable running off the top of her head, and terminating in an electrode box on the head of the bed. This arrangement allowed her enough slack wire so that she could turn over in bed and otherwise be comfortable, but did not allow her to sit up more than two feet without disconnecting the wires from the box, an event which would show up on the recording equipment as a tremendous amount of sixty cycle artifact. Thus her movements were well controlled.

Immediately above the observation window (about five and a half feet above the level of the subject's head) was a small shelf (about ten inches by five inches). Immediately above this shelf was a large clock, mounted on the wall.

Each laboratory night, after the subject was lying in bed, the physiological recordings were running satisfactorily, and she was ready to go to sleep, I went into my office down the hall, opened a table of random numbers at random, threw a coin onto the table as a means of random entry into the page, and copied off the first five digits immediately above where the coin landed. These were copied with a black marking pen, in figures approximately two inches high, onto a small piece of paper. Thus they were quite discrete visually.

This five-digit random number constituted the parapsychological target for the evening. I then slipped it into an opaque folder, entered the subject's room, and slipped the piece of paper onto the shelf without at any time exposing it to the subject. This now provided a target which would be clearly visible to anyone whose eyes were located approximately six and a half feet off the floor or higher, but was otherwise not visible to the subject.

The subject was instructed to sleep well, to try and have an OBE experience, and if she did so to try to wake up immediately afterwards and tell me about it, so I could note on the polygraph records when it had occurred. She was also told that if she floated high enough to read the five-digit number she should memorize it and wake up immediately afterwards to tell me what it was.

My conversation with Miss Z after I had prepared the target was, of course, minimal and could not have given her any clue as to the target number. In future experiments, however, it would be preferable for a second experimenter, who had had no contact at all with the subject, to prepare the targets.

Night IV - The Break-through
On reporting to the laboratory on the fourth night, Miss Z seemed to be determined to have the right kind of OBE experience. Although I had indicated complete satisfaction with her performance so far, she was angry at herself because she had not been able to float up and read the target number. Miss Z went quickly to sleep, entering Stages 3 and 4 less than fifteen minutes after going to bed.

The night was uneventful for the most part - there were several Stage 1 dream periods in the first two-thirds of the night, as would be expected for any normal subject. After four and a half hours of sleep, she had a Stage 1 dream period with REMs which lasted for half an hour. The EEG was technically rather poor on this night, being obscured with a great deal of sixty cycle artifact and requiring rather heavy high frequency filtering to make it clear, so the EEG findings should be taken with the realization that they are subject to more error than usual.

Miss Z's Stage 1 dream terminated with several minutes of intermittent body movements and EEG artifact. Then (at 5:50 A.M.) the occipital channel showed an enlarged, slow wave artifact, the REM channel showed no REMs, and the record looked like a Stage I tracing; however, I could not be sure due to the considerations mentioned above. At 5:57 A.M. the slow wave artifact was lessened and the record looked somewhat like Stage 1 with REMs, but I could not be sure whether this was a waking or a Stage I record.

This lasted until 6:04 A.M., at which time Miss Z awoke and called out that the target number was 25132.

This was correct (with the digits in correct order), but I did not say anything to her at this point; I merely indicated that I had written the number down on the record.

I then told her she could go back to sleep, but twenty minutes later I awakened her so that she could get ready to go to work. At this time, she described her experience as follows:

I woke up; it was stifling in the room. Awake for about five minutes. I kept waking up and drifting off, having floating feelings over and over. I needed to go higher because the number was lying down. Between 5:50 and 6:00 A.M. that did it. ... I wanted to go read the number in the next room, but I couldn't leave the room, open the door, or float through the door. . .. I couldn't turn off the air conditioner!

It should be mentioned that Miss Z had expected me to prop the target number up against the wall on the shelf; actually, I had laid it flat on the shelf, which she correctly perceived. Also, I had put a second number on a shelf in the equipment room, but she reported she could not get into this room to see the number.

Neither could she turn off the air conditioner, and she complained - that although it had been stifling, it was too cold in the room by that time.

Since Miss Z's correctly calling a five-digit number (P = 10^-5 [i.e., odds of 1 in 100,000]) was the first strong evidence that her OBE experiences contained a parapsychological element.

I inspected the laboratory carefully the next day to see if there was any way in which this number [Note 2] could have been read by non parapsychological means.

As a first alternative to an explanation involving extrasensory perception, we decided that "sophisticated" cheating by Miss Z was not impossible. She might have concealed mirrors and reaching rods in her pajamas and used these during the period when the EEG was difficult to classify (due to movement artifacts) to read the number. While this is possible, I personally doubt that it occurred.

The second alternative is that she might have seen the number reflected in the surface of the case of the clock which was mounted on the wall above it. This was the only reflecting surface in the room placed in such a way that this might have been possible. Both Dr. Hastings and I spent some time in the dimly lit room to dark-adapt our eyes, and tried to read a number from the subject's position on the bed, as reflected on the surface of the clock. As the room was dimly lit and the surface of the clock was black plastic, we could not see anything of the number. However, when we shone a flashlight directly on the number (increasing its brightness by a factor somewhere between several hundred and several thousand) we could just make out what the number was in the much brighter reflection.

Thus, although it seems unlikely, one could argue that the number constituted a "subliminal" stimulus in its reflection off the clock surface. Therefore, Miss Z's reading of the target number cannot be considered as providing conclusive evidence for a parapsychological effect. After calling out the number, Miss Z again returned to sleep and spent approximately twenty minutes in a stage where the EEG was again quite difficult to classify. It was a generally low voltage, flattened record which looked rather like a poorly developed Stage 1 record. However, there were no REMs to speak of, and there was only a small amount of alphoid activity. Upon awaking, she reported that she had had a number of floating sensations during this time.

Discussion
In the course of four nights in the laboratory, Miss Z reported three clear-cut incidents of "floating" and two instances of feeling completely out of her body. The floating incidents, according to her accounts, were all characterized by the feeling that she was starting to rise up above her body, but only slightly, and then [Note 3] being back in her body, usually waking in the process. The "nightmare" during her second laboratory night is not clearly classifiable as an OBE experience. Only the final night in the laboratory produced a report of an OBE experience giving fair evidence of parapsychological concomitants (her reading of the target number), but as this evidence is not conclusive, the remainder of this discussion will focus on the subjective experience of being out of the body, and on the concomitant psychophysiological states.

It is difficult to state conclusively what kind of EEG pattern accompanied the floating experiences and full OBE experience because we must depend on Miss Z's retrospective report for the approximate times when they occurred. In connection with most of these experiences, she reported waking up briefly several times during their course; thus, one would expect whatever pattern accompanied them to be mixed with transitory waking patterns, as well as with the body movement artifacts which generally accompany waking from sleep.

My general impression of the EEG correlates of Miss Z's floating and OBE experiences is that they occurred during a rather poorly developed Stage 1 pattern which was dominated by alphoid activity and often mixed with transitory periods of wakefulness. This alphoid activity was always one to one and a half cycles per second slower than her normal alpha rhythm. No REMs seemed to accompany these experiences and, judging from the one night when the plethysmograph was working satisfactorily and the two nights when the skin resistance channel was working satisfactorily, there are no marked autonomic alterations concomitant with the experiences; that is, heart rate stays at a normal, steady rate, and there is no pronounced change in either BSR or spontaneous GSR activity. 

Further, it can be stated with some certainty that Miss Z's OBEs experiences do not occur in a normal state of Stage 1 dreaming. She showed normal, well developed Stage 1 EEG and REM patterns, but she did not report OBE experiences in conjunction with these patterns unless they changed into the alphoid pattern, without accompanying REMs. Figure 1 shows a typical example of Miss Z's waking EEG pattern and an example of Stage 1 dreaming with REMs. Figure 2 shows a sample of Stage 2 sleep with an example of the prominent alphoid pattern she showed in conjunction with her OBE experiences; this particular example is taken from her second laboratory night when she reported seeing the time. 

Considering, then, that we have a fairly good correlation between Miss Z's reported OBE experiences and a relatively distinct neurophysiological pattern, how would we describe her physiological state? Here we run into considerable difficulty. The mixture of Stage 1 and pronounced alphoid activity, along with no REMs or cardiovascular or skin resistance changes, has not been described before, to my knowledge, in the sleep literature. [Note 4] The particular pattern cannot be unequivocally classified as a waking pattern, nor can it be unequivocally classified as any of the known stages of sleep. Nor is it a typical Stage 1 drowsy pattern by any means, because of the pronounced alphoid activity.