|Coined by||B. P. Wiesner (1942)|
|Definition||A term used to demarcate processes or effects associated with cognitive or physiological activity that fall outside of conventional scientific boundaries (ESP, for example).|
|Pronunciation:||Pronounced with a silent p, sounding like "sigh".|
The term was coined by biologist Berthold P. Wiesner, and first used by psychologist Robert Thouless in a 1942 article published in the British Journal of Psychology. Psi was argued by Thouless and Wiesner to offer a non-theoretical manner of referring to extrasensory perception and psychokinesis, these terms being unjustifiably loaded with suggestions as to how the phenomena were caused or experienced.
Traditionally the term has had two sub-categories:
- Psi-Gamma - Pertaining to paranormal cognition (ESP, remote viewing, etc.)
- Psi-Kappa - Pertaining to paranormal action (psychokinesis, etc.)
Although Thouless and Wiesner were careful to offer psi as merely referring to certain paranormal activity worthy of study, it has come to connote the processes that somehow cause them, or a certain faculty of human psychology. In a 1994 paper in the Psychological Bulletin, Daryl J. Bem and Charles Honorton defined psi thus:
The term psi denotes anomalous processes of information or energy transfer, processes such as telepathy or other forms of extrasensory perception that are currently unexplained in terms of known physical or biological mechanisms. The term is purely descriptive: It neither implies that such anomalous phenomena are paranormal nor connotes anything about their underlying mechanisms.
Similarly, according to the Parapsychological Association, psi can be
used either as a noun or adjective to identify paranormal processes and paranormal causation; the two main categories of psi are psi-gamma (paranormal cognition; extrasensory perception) and psi-kappa (paranormal action; psychokinesis), although the purpose of the term "psi" is to suggest that they might simply be different aspects of a single process, rather than distinct and essentially different processes.
However, it has been pointed out by parapsychologist Carl Williams:
Historically, the study of psi has been viewed as existing far outside the normal boundaries and concerns of 19th - and 20th - century science. Whether proposing the possibility of contact with the dead or novel forms of communication, books with titles such as Beyond the Reach of Sense (Heywood, 1974) and Beyond Reality (Rogo, 1990) establish psi as an object of scrutiny out of this world; and to many the study of psi and its existence are seen as existing in the Margins of Reality (Jahn & Dunne, 1987).
Scientific study 
In an experiment using neuroimaging to resolve the psi debate (Moulton and Kosslyn, 2008) wrote:
Functional magnetic resonance imaging (fMRI) was used in an effort to document the existence of psi. If psi exists, it occurs in the brain, and hence, assessing the brain directly should be more sensitive than using indirect behavioral methods (as have been used previously). To increase sensitivity, this experiment was designed to produce positive results if telepathy, clairvoyance (i.e., direct sensing of remote events), or precognition (i.e., knowing future events) exist. Moreover, the study included biologically or emotionally related participants (e.g., twins) and emotional stimuli in an effort to maximize experimental conditions that are purportedly conducive to psi. In spite of these characteristics of the study, psi stimuli and non-psi stimuli evoked indistinguishable neuronal responses-although differences in stimulus arousal values of the same stimuli had the expected effects on patterns of brain activation. These findings are the strongest evidence yet obtained against the existence of paranormal mental phenomena.
See also 
- Extrasensory perception
- List of psychic abilities
- Psi (disambiguation)
- Psi (Cyrillic) Legend Ѱ
- Enhanced Intuition
- Remote viewing
- Aura Manipulation/Control
- "The Parapsychological Association"
- "The Institute of Noetic Sciences"
- Rhine Psi Research Center
- Society for Psychical Research
- Psi Research Database
- Princeton Global Consciousness Project
- What do parapsychologists study?, Parapsychological Association (2007-02-03)
- Psi - Glossary of Key Words Frequently Used in Parapsychology, Parapsychological Association (2007-01-29)
- Thouless, R. H. (1942). "Experiments on paranormal guessing". British Journal of Psychology, 33, 15-27.
- Bem, D. J., & Honorton, C. (1994). Does psi exist? Replicable evidence for an anomalous process of information transfer. Psychological Bulletin', 115, 4-18.
- http://www.parapsych.org/glossary_l_r.html#p Parapsychological Association Glossary of Parapsychological terms
- Moulton, S. T., & Kosslyn, S. M. (2008). Using neuroimaging to resolve the psi debate. Journal of Cognitive Neuroscience, 20, 182-192.