Several theories have been proposed to explain the apparent linkage between alterations of consciousness and both spontaneous and laboratory psi performance.
William Braud (1980) has proposed that the lability of the subject's input-receiving system (i.e., the brain/mind) of the subject) is a key factor in psi experience. This lability (the ease with which a system can change from one state to another) characterizes alterations in consciousness.
Rex Stanford (1987) has discussed the psychophysical noise reduction that characterizes such consciousness-alteration methods as hypnosis and the ganzfeld. He suspects that the passive-experiential mood set advocated by White is more psi- conducive than an active, goal-oriented set. He also considers the role that ritual (e.g., hypnotic induction, attaching the ganzfeld goggles) might play in inducing a favorable set, thus facilitating high psi-scoring.
Honorton (1977) has outlined an information-processing model of psi based on a distinction between psi interactions (in which information is acquired by psi) and psi experiences (in which such information actually enters awareness). Psi-mediated awareness then becomes an act of signal detection; the signal/noise ratio can be reduced by enhancing internal attention states (e.g., via hypnosis, meditation, relaxation, dreaming, the ganzfeld).
Leonard George (1981) points out that mental imagery is a typical concomitant of psi-conducive states, and an increased orientation toward these images might make the detection of psi more likely during these types of consciousness alterations. If so, mental imagery training might be able to enhance positive psi-scoring.
Hans Eysenck (1975) has proposed that relatively low levels of cortical arousal expedite psi functioning. Because extraverts are characterized by chronically lower cortical arousal relative to introverts, this might explain the finding that extraverts make higher psi scores than introverts. Indeed, this is one of the few pieces of data in parapsychology that has been reported from different researchers with some consistency.
Another explanation of the link between psi and alterations of consciousness implicates the enhanced expectation of subjects who know they will be participating in a consciousnessalteration study. Indeed, the type of person volunteering for this type of study might be the kind of person who has a propensity for high psi-scoring (Rogo, 1976). Once the alteration of consciousness has been achieved, an implicit permission is granted for the subject to relax, turn his or her attention inward, and report unusual imagery that might be psi-related.