Comparisons between psi and perception without awareness (hence-forth PWA) (1) have been made throughout the history of parapsychology. Frederick Myers (1903) was perhaps the first researcher to suggest a relationship between the paranormal and information below the level of conscious awareness.
Since then, a number of researchers have been impressed by the apparent similarities between psi and PWA (see, e.g., Beloff, 1972; Dixon, 1979; Nash, 1986; Roney-Dougal, 1981, 1986; Schmeidler, 1986). It is important to note, as Beloff (1972) did, that the analogy can begin only at the point at which the information about the target has entered the cognitive system and is awaiting processing. A stimulus that is of such intensity to allow PWA is, nonetheless, a sensory stimulus. It has known physical qualifies (albeit weak), and it is available to the known sensory apparatus of the percipient. A psi input, however, is, by nature, not available to any of the recognised senses, and, in an experimental situation, is actively shielded from the percipient. What the present article is concerned with, therefore, is the way the information (either psi information or information that is perceived outside of 'awareness) is processed once it is in the system.
Assuming that psi processing is unconscious in nature (for justification of this assumption, see, e.g., Broughton, 1988; Stanford, 1990), then it would be reasonable to suggest that it might be processed similarly to other unconscious phenomena. (2) If this were the case, then it would add considerable credibility to the psi hypothesis. It would do this in the general sense that learning that psi has certain properties indicates that it has existence and that it can be studied in similar ways to other psychological phenomena. Comparing psi and PWA may also help shed some light on the way in which weak stimuli are processed (be they psi stimuli or weak sensory stimuli). Nash (1986) contended that many of the factors that have been previously found to be important in psi research were later found also to apply to PWA, and vice versa. For example, Nash identified, among others, that the drawing of responses, unintentional negative scoring (or "missing"), improved performance at the beginning and end of testing (U-shaped scoring distribution), and the effect of believers versus disbelievers were all effects first found in parapsychology that were subsequently found to have a similar effect in PWA research. Likewise, sensory deprivation, relaxation, perceptual defence, galvanic skin response, and right hemisphericity were all effects that were first found to influence PWA scores and were later found to have an effect on psi tasks.
Moreover, understanding PWA is important for parapsychologists because it offers another explanation for certain kinds of anomalous experience that does not imply psi. PWA offers a possible mechanism for many experiences in which people claim to have been influenced by some "unknown" or anomalous means. In many cases, the stimulus identified by the percipient as being anomalous may simply have been outside of awareness. This may have led the percipient to conclude that, as he or she had no conscious awareness of being influenced, then there must have been a "paranormal" force at work.
There have been many comparisons between the two phenomena over the years (see, e.g., Beloff, 1972; Dixon, 1979; Nash, 1986; Roney-Dougal, 1986, 1987; Schmeidler, 1986). One comparison is at the subjective level. Responses in both PWA tasks and psi tasks are often described as guesses, and it is often impossible to distinguish between guesses in the two types of task. In an experiment related to this theme, Miller (1940) presented participants with a PWA test disguised as a test of telepathy. None of the participants were aware that there was a PWA component to the task and were surprised to learn that their guesses were not based on telepathy but had actually been influenced by a weak sensory stimulus. …