Psi is the twenty third symbol in the late Greek alphabet. It came into being when the Greeks converted the Phoenician alphabet to phonetics.

The five short vowels A, E, I, O, and U were from aleph, hey, yod, ayin, and vav respectively. Then Eta, ( long 'e' ), Omega, ( long 'o' ), Theta ( the 'th' sound in Theta ), Phi ( the 'f' sound ) and Psi ( the 'sigh' sound in cyan ) were added. Psi originally represented sounds that occurred in Greek but not in Phoenician. The Greek alphabet was later assimilated by the Romans who replaced Psi with other letter combinations that produce the same sound. The Psi symbol has not completely disappeared. It remains in use today as a symbol to designate functions in scientific formulas.

Parapsychologists also associate ψ with the paranormal, deriving the relationship from the "psy" sound in parapsychology. Although core ψ subject matter revolves around psychic phenomena such as telepathy, precognition, clairvoyance and other manifestations of consciousness that transcend the human physical condition, the range of ψ phenomena has since become a catch- all phrase for anything paranormal, including UFOs. PSI phenomenon gained further popularity in 1996 when the Canadian sci-fi television series PSI Factor began airing. It lasted 88 episodes, covered a wide range of paranormal topics and ended in the year 2000. Although fictional, it was written in a docudrama style and featured commentary by well-known actor and proponent of ψ phenomenon Dan Akroyd.

In 2011 USI joined the Paranormal Site Investigators ( Logo left ) in order to network on areas of ψ phenomena that intersect with ufology. Associate members receive PSI Newsletters and Journals, as well as occasional email updates. At the time this article was written, The Paranormal Site Investigators approach to fieldwork was to monitor a location with audio-visual recording devices, establish a baseline for the normal environment, then investigate anything out of the ordinary as fully as possible. PSI also has an Education Committee comprised of education professionals. One of their objectives is to gain academic acceptance for the study of anomalous experiences by University students. PSI has allowed PhD candidates to advance their education by participating in field-based research studies.