What Is PSI?
PSI (often written as psi, using the Greek letter Ψ) is the umbrella term used in academic parapsychology to refer to all anomalous psychological phenomena — any process of information transfer or physical influence that cannot be explained by known sensory or motor channels. PSI encompasses both receptive phenomena (acquiring information without normal sensory input) and expressive phenomena (influencing physical systems without normal physical interaction).
Categories of PSI
PSI phenomena are traditionally divided into two broad categories. Psi-gamma refers to anomalous cognition — the acquisition of information through non-sensory means. This includes ESP (Extra-Sensory Perception), RV (Remote Viewing), telepathy, clairvoyance, and precognition. Psi-kappa refers to anomalous perturbation — the influence of physical systems through non-physical means. This includes PK (Psychokinesis), telekinesis, and what parapsychologists term RSPK (Recurrent Spontaneous Psychokinesis) — the proposed mechanism behind poltergeist activity.
Research History
Academic PSI research began with the founding of SPR (Society for Psychical Research) in London in 1882 and has continued through university-based laboratories and independent research institutes. Key research programs have included J.B. Rhine’s card-guessing experiments at Duke University, the SRI (Stanford Research Institute) remote viewing program, Ganzfeld telepathy experiments at multiple institutions, and the Global Consciousness Project at Princeton. These programs have produced a body of statistical evidence that proponents argue demonstrates small but consistent PSI effects.
The Evidence Debate
The status of PSI evidence is one of the most contentious issues in science. Meta-analyses of certain experimental protocols — particularly Ganzfeld experiments and random number generator studies — have shown hit rates above statistical chance, and these results have been replicated across independent laboratories. Critics counter that the effect sizes are small, the phenomena cannot be produced on demand, no physical mechanism has been identified, and methodological concerns may account for the positive results.
PSI and Paranormal Investigation
While academic PSI research operates in controlled laboratory settings, the claimed phenomena overlap significantly with what paranormal investigators encounter in the field. Mediumship, psychic impressions during investigations, and cases involving apparent poltergeist activity all fall within the PSI framework. Understanding PSI research provides investigators with a scientific context for evaluating experiential claims.
Related Terms
PSI encompasses ESP (Extra-Sensory Perception), RV (Remote Viewing), PK (Psychokinesis), and RSPK (Recurrent Spontaneous Psychokinesis). Research is conducted at institutions including SRI (Stanford Research Institute), DOPS (Division of Perceptual Studies), IONS (Institute of Noetic Sciences), and through organizations like SPR (Society for Psychical Research).