Agent:  Person who tries to communicate information to a percipient in an ESP experiment, or to influence behaviour of animate or inanimate targets in a PK experiment.

Altered State(s) of Consciousness (ASC):  Umbrella term covering any mental state different from that of normal consciousness. See also Meditation.

Animal Telepathic Communication:  The process of a human connecting telepathically to an animal.  The human is generally in a quiet, meditative state of mind and may receive a variety of intuitive impressions, images, feelings, emotions, or words in their mind from the animal.  See also Telepathic Interspecies Communication.

Animal Psi:  Psi exhibited by an animal, sometimes abbreviated to 'anpsi'.

Apparition:  Visual appearance to a person, normally in a waking state, of another person who is not actually present and may well be deceased. Apparitions may include scenes (countryside, and so on). See also Ghost; Hallucination.

Apport:  Physical object which appears in an enclosed space into which orthodox entry is impossible. Implies a process of matter passing through matter. See also Teleportation.

Astral Body:  Occultist term for the double of a person’s physical body, which can separate from it during a dream, an OBE, or at death. See also Etheric Body.

Astral Projection:  The separation of a person's astral body, which is able to move outside the confines of the physical body.

Astrology:  Interpretation of the motion of the heavenly bodies as influencing a person’s (or institution’s) life course.

Aura:  Field of luminous radiation surrounding a physical body, like a halo; usually seen only by a clairvoyant.

Automatic Writing:  Form of automatism where a person writes intelligibly in a recognized language, but without conscious knowledge of what is being written.

Automatism:  Complex activity executed while in a state of dissociation. Automatic writing is one example.

Bilocation:  The seeing, or being aware of, an individual in two places at the same time.

Biofeedback:  The monitoring of physiological processes, normally not amenable to voluntary control, with the goal of controlling them.

Blind:  Procedure for assessing experimental results in which a judge is ignorant of the way in which the targets and responses were related. See also Double Blind.

Boggle Threshold:  A term coined by Renée Haynes to indicate the point at which a phenomenon is considered highly unlikely to be real.  This point is subjective and will vary from individual to individual.

Book Test:  Survival test in which information is transmitted between communicator and medium based on a passage on a specific page in a book which neither the medium nor sitters would be aware of, thus ruling out normal knowledge by either alone, or telepathy between them.

Cabinet:  Enclosed, usually a curtained, space, often used by a physical medium as a place within which s/he concentrates her/his psi faculty.

Card Guessing:  A method of testing for ESP where a percipient tries to guess the identity of cards which s/he cannot see.

Chair Test: Before a public meeting with no members of the audience present, a chair is chosen randomly and the percipient describes the characteristics of the person who will occupy that chair during the meeting.

Chance Score:  Score achieved in a psi test that could have been expected without the intervention of paranormal effects. See also Probability.

Cipher Test:  A living person devises a cipher known only to him- or herself.  Attempts are made to break it while the originator is still alive but if these fail, yet the cipher is broken after the originator's death by paranormal means (rather than a computer program), that is considered evidence for the originator's survival.

Clairaudience:  Process of acquiring information paranormally by attending to auditory imagery or hallucinatory voices. See also Clairvoyance.

Clairvoyance:  Process of acquiring information paranormally about a psychical event or object.

Closed deck:  Pack of cards used in a psi test in which each type of symbol occurs the same number of times, such as in a pack of ordinary playing cards. See also ESP Cards; Open Deck.

Coincidence:  Occurrence of two or more significantly related events within a short period of time, which do not appear to have any orthodox causal links between them.

Combination Lock Test: A combination padlock is set by a person who is the only one who knows the number.  If attempts to elicit the number are unsuccessful while the owner is still alive, yet the number is obtained by paranormal means after the owner's death, that is evidence of survival.

Communicator:  Personality, purportedly of a deceased being, who communicates with living persons, often via a medium. See also Drop-in Communicator.

Control:  Personality, purportedly of a deceased being, who normally takes charge of a medium during trance, and sends messages to the sitter(s) from the communicator(s).

Control Group:  Group of persons assessed for performance relative to an experimental group, although not subject to (all of) the same procedures.

Correlation:  Measure of the degree to which two variables vary together in a statistical assessment. See also Regression.

Critical Ratio:  Useful method of stating the statistical significance of a score in aforced-choice test of ESP or PK.

Cross-Correspondence:  Process of putting together fragmentary items of information, usually obtained from two or more independence mediums, which are initially without significance, but which when assembled together convey an intelligent message or make a significant allusion.

Cryptomnesia:  Person’s unawareness, or forgetting, that s/he has normally acquired certain information. It may be remembered later, but its normal source is forgotten. Sometimes called ‘source amnesia’ or ‘unconscious plagiarism’ [Offered as an alternative explanation of some allegedly paranormal awareness].

Deathbed Experience:  Experience of a dying person, in which s/he is aware of dead friends or relatives. Akin to an altered state of consciousness. See also Near-Death Experience.

Decline Effect:  Decrease of frequency of correct scores when a psi test is repeated.

Déjà Vu:  Feeling of a person that s/he has already lived through the current experience. [When s/he also knows in advance the next stage in the experience, the state was called ‘promnesia’ by Myers.]

Dermo-Optical Perception: The ability to obtain by touch information normally only available to sight.

Development Circle: A group that meets in order to allow its members to develop mediumistic abilities, usually under the direction of an experienced medium.

Dice-Throwing Experiment: Psychokinesis test in which a subject tries to influence the fall of dice.

Direct Voice: Mediumistic phenomenon in which a voice ostensibly of a spirit is heard by sitters.

Direct Writing: Paranormal production of writing without the intervention of a medium.

Discarnate Entity:  Disembodied being, assumed to be that of a deceased person.

Displacement: A term used in card-guessing tests to indicate the correct choice of cards either in front or behind the target in a series.

Dissociation:  Mental process which leads to the development of separate centres of consciousness, or of activity outside normal consciousness.

Direct Mental Interaction with Living Systems (DMILS):  Tests where a person (an ‘agent’) tries to interact with a biological target system, such as another person’s physiological responses or the behaviour of animals.

Doorway Test: A test to determine the reality of auras.  A person either stands close to the edge of a door or not on random trials and the percipient says whether or not they are doing so.  Statistically significant results would indicate that the percipient was able to determine the person's presence by means of the aura projecting beyond the physical body.

Double Blind:  Procedure for assessing experimental results when both the judge and the experimenter are blind.

Down Through (DT):  Technique for testing clairvoyance when a percipient has to guess the order of the target symbols, from top to bottom, in which a set of test cards are stacked. (Bottom-to-top order is ‘Up-through’.)

Dowsing:  Paranormal detection of subterranean liquids and minerals using a divining rod or pendulum.

Drop-in Communicator:  Communicator who manifests uninvited at a sitting, and whose existence is unknown both to the medium and the sitters at her/his first appearance.

Ectoplasm:  Substance which emanates from some physical medium (usually when in a trance) and from which materializations seem to be formed.

Electroencephalography (EEG):  Method of recording and amplifying fluctuations in voltage in a person’s brain.

Electronic Voice Phenomenon (EVP):  Voices, usually of deceased beings, recorded paranormally on a magnetic tape. See also Instrumental transcommunication.

ESP: see Extrasensory Perception.

ESP Cards:  Special kind of closed deck pack of cards; normally consists of 25 cards in five sets of five different symbols.

Etheric Body: see Astral Body

Experimenter:  Person in charge of an experiment, and perhaps its designer; usually also responsible for the appraisal of its results.

Experimenter Effect:  Influence on an experiment apparently due to some aspect, conscious or otherwise, of the experimenter’s interaction with his subjects. May include the experimenter’s attitude to his experiment, or to the whole field.

Extrasensory Perception (ESP):  Umbrella term for paranormal acquisition of information about persons, events or objects. See also Psi.

Filter Hypothesis:  Explanation of the occurrence of psi in terms of the dramatic or emotional character of the information, which breaks through the defences of a person and thus gains his/her attention.

Focus: A living person who is the centre of poltergeist activity.

Forced-Choice Test:  Guessing test where a percipient must choose one from a limited number of targets.

Free-Response Test ESP:  Test in which there is an unlimited (or very large) number of targets.

Ganzfeld:  Homogeneous environment created for a percipient by playing white noise through headphones and furnishing a uniform visual field by (for example) translucent goggles.

General Extrasensory Perception (GESP):  [Umbrella term referring to] clairvoyance, telepathy or both, when the conditions make it impossible to distinguish them.

GESP: see General Extrasensory Perception.

Ghost:  Popular term for apparition, or for an invisible entity thought to be the cause of a haunting.

Glossolalia:  Speech of a person in an invented, or at least unrecognized, language. See also Xenoglossy.

Goat:  Person who doubts that s/he can succeed in a task requiring ESP which s/he is asked to undertake. Often used more loosely to refer to a person who doubts the possibility of psi. See also Sheep.

Hallucination:  Sensory experience which seems to be normal to the person, but in which the physical objects experienced do not in fact exist within range of his/her normal senses. It is ‘collective’ if experienced by more than one person; ‘veridical’ if the information obtained is correct.

Haunting:  Occurrence of paranormal phenomena on several occasions at one particular location. Often associated with apparitions or poltergeists.

Hit:  Successful response in a psi test. Opposite of Miss.

Hyperaesthesia:  Excessive sensitivity of a person’s sensory means.

Hypnagogic:  State of consciousness just at the point of going to sleep; vivid imagery in state of relaxation.

Hypnopompic:  State of consciousness just at the point of waking up.

Hypnosis:  State of consciousness, usually induced, in which a person is susceptible to suggestion.

Instrumental Transcommunication (ITC):  Anomalous communications received through electronic media.

JOTT (Just One of Those Things):  a spatial discontinuity, typically the unaccountable displacement of an article, known as a JOTTLE see also Apport.

Judge:  Person who appraises targets, and/or responses to them, after psi tests have been carried out.

Karma:  Sanskrit word referring to actions in one incarnation that have effects in a later incarnation. Popularized in the West in the writings of theosophy and occultism. May relate to reincarnation.

Kirlian Photography:  Special kind of high-frequency electrophotography which records radiation field surrounding the photographed object.

Levitation:  Lifting and suspension of an object or a person in the air without apparent use of orthodox physical or technological means.

Lucid Dream:  Dream in which a dreamer is aware that s/he is dreaming.

Macro-PK: observable large-scale PK (psychokinesis), such as table-tipping, levitation, apports and other effects described in physical mediumship and poltergeist episodes. 

Map Dowsing: A form of dowsing in which a map is used rather than the actual location.

Materialization:  Appearance of a person or an object in apparently solid form, usually during a sitting held by a physical medium; possibly produced out of ectoplasm.

Meditation:  Umbrella term covering techniques for attaining altered states of consciousness.

Medium:  Person who regularly, and often at will, receives purported communications from the dead (‘mental medium’) and/or causes physical materializations (‘physical medium’).

Mentalism: A stage act simulating telepathy.

Mesmerism:  Term, made popular in the late 18th and early 19th centuries, for what is now called ‘hypnosis’. Also known as ‘animal magnetism’.

Micro-PK: small-scale PK (psychokinesis), demonstrated statistically in experiments by means of dice throwing, random event generators, etc

Mind-reading: see Telepathy.

Minilab:  Secure glass tank containing objects wich are used as targets for PK by living subjects and possible discarnate entities.

Miss:  Unsuccessful response in a psi test. Opposite of 'hit'.

Muscle Reading: A stage act in which the performer is able to find a hidden object known to another by holding their arm and going to the object's location. The performer claims to be using telepathy but is guided by unconscious muscular cues.

Near-Death Experience:  Experience, often similar to an apparition or an OBE, undergone by a person on the brink of death. See also Death-Bed Experience.

Non-Intentional Psi:  Ability of person to effect psi in response to his/her needs, but not by conscious effort.

Observational Theories:  Theories which assert that the observation of the results of an experiment is necessary for psi to effect, retroactively, those results. See also Retroactive PK.

Occultism:  Umbrella term concerning doctrines such as divination, magic and astrology.

Open Deck:  Deck of cards in which the numbers of symbols of different types are determined by a table of random numbers. See also Closed Deck.

Ouija Board:  Board marked up with letters and numbers, used as an aid to receive messages delivered from a communicator at a sitting, and answers supplied to questions posed by sitters or medium.

Out-of-the-Body Experience (OBE):  Experience of being spatially separated from the physical body, varying from being in a physical-like space that appears to include the location of the physical body to being in a space differing to a lesser or greater degree from physical manifestation.

Paranormal:  Phenomenon which is considered impossible according to the established scientific world-view.

Parapsychology:  Scientific study of psychical phenomena. Sometimes used as a synonym for ‘psychical research’, sometimes restricted to its experimental aspects.

Percipient:  Person who experiences extrasensory influence or impression, and is often under test for psi ability. See also Subject.

Phantasm: A hallucinatory sensory impression or illusion.

PK: see Psychokinesis.

Placebo:  Treatment of a control group in an experiment which simulates treatment received by the experimental group but in fact is innocuous; object (often medicinal) given to a person without known beneficial effects other than that of suggesting that it will help.

Placement Test:  Test for PK in which a percipient has to make test objects land in a given area.

PMIR: see Psi-Mediated Instrumental Response.

Poltergeist:  Physical form of psychical phenomenon, often involving dislocation and transportation of objects and even apports (although, unlike hauntings, rarely apparitions). Frequently regarded as of a mischievous, destructive or pathological character.

Possession:  Control of person (often a medium) by a discarnate entity.

Precognition:  Paranormal (non-inferential) knowledge of a future event. If event is interpreted as a target, then precognition becomes a form of ESP. See also Premonition; Retrocognition.

Premonition: Intuitive sense of a future event, of a personally significant and often threatening nature.

Presentiment: Unconscious form of precognition or premonition, demonstrated statistically in laboratory settings. 

Probability:  Of a given result in an experiment, proportion of occasions that it would be expected on chance alone: the lower the probability, the more significant the results.

Prophecy: see Precognition.

Psi:  Umbrella term covering ESP and PK, in colloquial usage equivalent to 'psychical phenomena'.

Psi-Conducive:  Environment or person, in ordinary life or the laboratory, favourable for the occurrence of psi. Opposite of psi-inhibiting.

Psi Faculty or Ability:  Capacity of a person to effect psi.

Psi-Hitting: Percipient's rate of scoring hits in a series of psi tests is above chance.  Opposite of psi-missing.

Psi-Inhibiting:  Environment or person, in ordinary life or the laboratory, unfavourable for the occurrence of psi. Opposite of psi-conducive.

Psi-Mediated Instrumental Response (PMIR): Explanation of spontaneous psi events in terms of an organism’s capacity to scan its environment and respond appropriately to it, sometimes without understanding why.

Psi-Missing:  Percipient’s rate of scoring hits in a series of psi tests is below chance. Opposite of psi-hitting.

Psyche:  Psychological core of a person; sometimes refers to his/her soul.

Psychic [adjective] or Psychical: see Paranormal.

Psychic: [noun] Person gifted at effecting psi.

Psychic Healing:  Paranormal medical practice, including immersion, psychic surgery, laying on of hands, and forms of healing at a distance. Often spontaneous, but also testable in the laboratory.

Psychical Phenomena:  Umbrella term covering phenomena not explicable by orthodox scientific theories (including medicine and technology).

Psychical Research:  Umbrella terms covering all types of study of psychical phenomena. See Parapsychology.

Psychokinesis (PK):  Paranormal influence of the mind of a person upon physical objects. See also Macro-PK, Micro-PK, Recurrent Spontaneous Psychokinesis (RSPK).

Psychometry:  Process by means of which a person, often a medium, holds an object and thereby paranormally obtains information about its history, and (sometimes) about persons who have held it before.

Psychophysics:  The science of the relationship between the mental and the physical, or between subjective sensations and experiences and their physical stimuli.

Psychosomatic:  Type of bodily illness or disease caused, or aggravated by worry, anger, or other emotional states.

Quantum Mechanics:  Branch of physics concerned with the ultimate constituents of matter.

Radionics: A method of diagnosis and treatment based on differential patterns of energy in healthy and unhealthy organisms.

Random Numbers:  Sequence of numbers produced by some process which, it is hoped, does not follow any law or regularity. [When produced by a mathematical process which contains no periodic properties, they are called ‘pseudo-random numbers’.]

Random Event or Number Generator (REG or RNG):  Electronic apparatus involving a random physical process, from which random numbers are generated, to be used as targets in a psi test.

Raudive Voices: see Electronic Voice Phenomenon.

Receiver: see Percipient.

Recurrent Spontaneous Psychokinesis (RSPK):  Repeated occurrence of PK in a given place over a period of time. Associated with poltergeists.

Regression [in hypnosis]:  State in which a hypnotized person seems to return to a previous period of existence, either in his current life or a possible previous life.

Regression [in statistics]:  Method of fitting a curve to data obtained from a test. See also Correlation.

Reincarnation:  Form of survival in which a soul passes from one physical body at its death and later becomes reborn in another physical body. (According to Hinduism, Buddhism and some occultist teachings, karma influences the process.)

Remote Viewing:  Form of GESP in which a percipient, although unaware of an agent’s location and surroundings, tries to describe them.

Repeatability:  Property of a phenomenon such that it can be reproduced, under specified conditions, whenever it is required.

Response:  Act carried out by a subject in accordance with the requirements of an experimenter (for example, guess made by a percipient when attempting to identify a target in a psi test).

Retroactive PK:  Influence exerted by a percipient or agent on an experiment after it has been run.

Retrocognition:  Form of ESP in which an event of the past is described by apparently paranormal means. See also Precognition.

RSPK: see Recurrent Spontaneous Psychokinesis.

Run:  Sequence of trials in a test.

Score:  Number of hits achieved in a run. See also Chance Score.

Séance:  see Sitting.

Second Sight: Term for psychic ability, particularly associated with Scotland. 

Sender: see Agent.

Sensitive: see Medium; Psychic.

Series:  Collection of runs, taken together for some purpose of the experiment group of spontaneous cases being considered together with regard to common features.

Session:  Period during which a sitting, or run of trials, continues with little or no interruption.

Sheep:  Person who believes that s/he can succeed in a psi task that s/he is about to undertake. Often used more loosely to refer to anyone who believes in the possibility of psi. See also Goat.

Sheep-Goat Effect:  Tendency of sheep to psi-hit, and goats to psi-miss.

Significance:  The odds against chance that a particular circumstance can occur.

Sitter:  Participant at a sitting.

Sitting:  Session usually held with a medium.

Slate Writing: The appearance of writing on a slate in the presence of a medium.

Somnambule:  Sleep-walker; a person under deep hypnosis.

Spirit: see Discarnate Entity.

Spirit Photography: The appearance of images of the deceased on photographic film or plates. See also Thoughtography.

Spiritualism:  View that human personality survives death, and that it is possible to obtain evidence of this through communications from discarnate entities. (To be distinguished from the religious view, also called ‘Spiritualism’, which centres on the belief in discarnate entities and their presumed teachings.)

Spontaneous:  Type of psychical phenomena which take place in ordinary life, often without warning.

Stacking Effect: An artefact in an experiment caused by similarities in guessing patterns leading to a spuriously significant result.

Standard Deviation: Statistic which indicates the variation in the values of a set of data (for examples, scores).

Subject:  Person participating in an experiment; usually a percipient, but sometimes either him/her or an agent.

Super-ESP Hypothesis: The hypothesis that any information that could be obtained from an alleged discarnate entity could in theory be gleaned by extrasensory perception between living individuals.  The survival hypothesis is not therefore the only, nor the simplest, explanation for the communication.

Survival:  Existence of the discarnate entity after the death of (the physical body) of a person. Reincarnation is an example.

Synchronicity:  Acausal occurrence of events forming a significant coincidence.

Table-Tilting:  Form of automatism in which several persons put their finger tips on the top of a table, when it moves and/or taps out messages in a code.

Target:  Object (mental or physical) which a percipient in a test attempts torespond to (for ESP), or affect (for PK).

Telekinesis:  Term used in older literature to describe PK.

Telepathic Interspecies Communication:  The process of a human connecting telepathically to an animal.  The human is generally in a quiet, meditative state of mind and may receive a variety of intuitive impressions, images, feelings, emotions, or words in their mind from the animal.  See also Animal Telepathic Communication.

Telepathy:  Paranormal passage of information from one person to another.

Theosophy:  Forms of philosophical and religious doctrine claiming access to a direct knowledge of God. For some theosophists, means of access include supernatural (and thus, perhaps, paranormal) revelation.

Thought Transference: see Telepathy.

Thoughtography:  Paranormal appearance of images on photographs.

Trance:  State of dissociation, such as is achieved by (auto-) hypnosis, in which asubject is susceptible to suggestion or automatism; condition of many mediumswhen they undergo changes of personality and seem to give communications fromdiscarnate entities.

Travelling Clairvoyance: see Out-of-the-Body Experience.

Trial:  Test, usually one in a series or run.

Ufology:  Study of unidentified flying objects and related phenomena.

Veridical:  Property of information (including apparitions, dreams and hallucination) such that it corresponds with the relevant piece of reality.

Xenoglossy:  Speech of a person in a recognized language which, however, s/he has not learnt normally. See also Glossolalia.

Zener Cards:  see ESP Cards.