Academic journal article The Journal of Parapsychology

Pk Tests in a Pre-Sleep State

Academic journal article The Journal of Parapsychology

Pk Tests in a Pre-Sleep State

Article excerpt

ABSTRACT: In an experiment with a single participant, the author, signals from a weak vibrator were presented at random time intervals to the participant, while he was ready to fall asleep at night. A pilot test of twenty 15-minute sessions indicated that this sleepy attention to the signals produced a reduction of the signal frequency, z = 2.45, p = .014, two-tailed, and a bunching of the signals along the time axis, z = 1.63. The subsequent main experiment, comprising 40 night sessions, confirmed the signal frequency reduction, = 2.24, p = .013, one-tailed, and the bunching effect, z = 2.85, p = .0022, one-tailed. In parallel with the night sessions of the main experiment there were added 40 day sessions in which the participant, exposed to the random vibrator signals, was fully awake and attempting to visualize vivid colors. These sessions gave a smaller reduction in signal frequency, z 1.01, ns, and a slightly negative bunching effect, z = -0.71, ns.

A large number of studies have already explored the PK performance of participants in special mental states, induced by hypnosis, meditation, mental imagery, or other induction procedures (Gissurarson, 1992). A common aim of these studies was the search for ways to produce PK effects more reliably or more strongly, such as to allow for more efficient studies of the basic PK mechanism and perhaps even for PK applications. These studies may be roughly divided into two classes. In the first class, participants are unselected or selected by formal rules (e.g., by the requirement that they be artists, or have meditated for 3 years). The studies of this class aim at particularly objective results that might be replicated by other researchers. However, even if all procedures are well specified and documented, the participants' perceptions of the test situation and their emotional reactions may vary uncontrollably; also, a subtle experimenter effect may be difficult to replicate.

The second class of studies works with a few highly selected participants, sometimes even with the experimenter as the only participant, the hope being that one might get stronger effects and better understand the individual approaches that lead to PK success. The experiment reported in this article belongs to this latter class, with myself acting as the only participant. I used as targets random time intervals. Let us therefore discuss first some previous experiments with random time intervals to get a feeling for the psychological conditions that might favor a lengthening or shortening of the intervals.


A Geiger counter exposed to a weak radioactive source may appear to be a good source of random time intervals. Under ideal conditions, the signals arrive randomly in time in the sense that the probability of observing a signal in a small time interval dt is proportional to dt and independent of when the previous signal has arrived. A first successful PK experiment with a Geiger counter, in which the participants tried to affect the number of counts in 1-min intervals, was reported by Chauvin and Genthon (1965). Unfortunately, it is difficult to stabilize the base counting rate of a Geiger counter, and the system may need some recovery time after each count so that the observed events are not truly independent. Therefore, Chauvin and Genthon had to alternate high-aim and low-aim runs, and they had to apply less powerful statistics than could have been used for truly random events.

Such imperfections of a Geiger counter are not critical, however, if one uses the Geiger counter (sometimes also an electronic noise source) as the heart of a digital random number generator (RNG; Schmidt, 1970). With the help of the digital RNG one can then produce random time intervals that permit an efficient statistical evaluation and can be made to approximate the distribution of signals from an ideal Geiger counter as closely as desired. …

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