Psychics and mediums: the evidence

• A. A belief that the physical world is an illusion created by the mind
• B. A claim that a person can acquire information about people, objects, or events through means not explained by known sensory or inferential channels ✓
• C. A religious conviction that the soul survives bodily death
• D. A psychological diagnosis describing a dissociative personality disorder

Why: Psychic claims are assertions that information is obtained through paranormal means, such as telepathy, clairvoyance, or precognition, rather than through the ordinary senses or reasoning. Option B captures this by specifying acquisition of information through channels unexplained by known mechanisms.

• A. The practice of using a physical instrument to detect electromagnetic fields
• B. The claim that a person can communicate with the deceased or other non-physical entities on behalf of living clients ✓
• C. A form of meditation designed to increase physical endurance
• D. The ability to move objects by mental force alone

Why: Mediumship refers specifically to the purported ability to act as an intermediary between the living and the dead or other spirits. Option D describes psychokinesis, a distinct claim, which is why it is not the correct definition of mediumship.

• A. Retrocognition
• B. Psychometry
• C. Clairvoyance ✓
• D. Ideomotor response

Why: Clairvoyance ('clear seeing') is the claimed perception of distant or hidden information without sensory contact. Psychometry refers to sensing information from handling objects, and retrocognition refers to knowledge of past events, so those are distinct claims.

• A. Because psychic abilities can only be measured in sealed laboratory chambers
• B. Because vague definitions make claims untestable, so precise definitions are needed to determine what observations would count as evidence for or against them ✓
• C. Because operational definitions are required by law for any claim about the supernatural
• D. Because definitions allow practitioners to charge higher fees for their services

Why: Unfalsifiable or loosely worded claims cannot be meaningfully tested. Operational definitions specify observable criteria, allowing researchers to design experiments and judge whether results support or fail to support a claim.

• A. They always use standardized, double-blind protocols
• B. They frequently rely on vague or general statements that many people could apply to themselves, a pattern sometimes called the Barnum or Forer effect ✓
• C. They are always recorded in full by independent observers
• D. They produce identical results across every participant

Why: Readings often contain broad, flattering, or ambiguous statements that feel specific to the listener, a phenomenon known as the Barnum or Forer effect. This vagueness makes it hard to distinguish genuine information from ordinary inference, cold reading, or confirmation bias.

• A. Harry Houdini
• B. Richard Hodgson ✓
• C. Joseph Jastrow
• D. Hans Bender

Why: Richard Hodgson, an American lawyer who joined the Society for Psychical Research, investigated the medium Leonora Piper extensively. He later concluded that some of her results were unusually impressive, though he remained cautious about explaining them, illustrating the early attempts to test mediums systematically.

• A. To train professional mediums
• B. To certify the authenticity of spirit photographs
• C. To investigate spiritualist claims using scientific methods ✓
• D. To promote the use of hypnosis in medicine

Why: Funded by a bequest from Henry Seybert, the commission was tasked with examining spiritualist phenomena scientifically. Its members, including William Pepper and George Fullerton, ultimately found that the phenomena they examined were fraudulent or unsupported, making it one of the earliest formal institutional tests of mediumship.

• A. Harry Houdini ✓
• B. David Devant
• C. John Nevil Maskelyne
• D. Howard Thurston

Why: Harry Houdini spent much of the 1920s exposing mediums, often by replicating their tricks on stage and publishing exposés. He famously investigated Mina 'Margery' Crandon, whose séances he publicly challenged, using his knowledge of stage magic to explain the methods behind supposed paranormal effects.

• A. Use of too many participants
• B. Reliance on anecdotal reports and insufficient controls against fraud ✓
• C. Excessive use of statistical analysis
• D. Publishing results in peer-reviewed journals

Why: Many early investigations relied heavily on personal accounts, sittings with limited oversight, and inadequate safeguards against deception. Later researchers introduced controls such as blind protocols, sealed conditions, and independent observers to reduce the chance that fraud or suggestion could explain the results.

• A. Observational studies of spontaneous psychic experiences in daily life
• B. Controlled tests in which a receiver attempts to identify a target sent by a sender while under sensory deprivation ✓
• C. Historical surveys of medium biographies
• D. Physical measurements of ectoplasm under infrared light

Why: Ganzfeld experiments place a receiver in a state of mild sensory deprivation, often with halved ping-pong balls over the eyes and white noise, then ask them to pick the target image or clip sent by a sender. Their results and methodological critiques, such as issues with randomization and sensory leakage, have been widely debated.

• A. Reading a sealed letter without opening it using special equipment
• B. Inferring information about a person from their appearance, body language, and responses without any prior knowledge of them ✓
• C. Obtaining private information about a client by hacking into their personal records
• D. Entering a trance state that allows direct communication with the deceased

Why: Cold reading is a set of techniques where a reader makes accurate-seeming statements by observing subtle cues such as clothing, age, grief, and reactions to guesses, while appearing to have no prior information about the person.

• A. Reading a client's mind through heightened emotional states
• B. Using information gathered in advance about a client, such as from social media, public records, or conversations with acquaintances ✓
• C. Reading tarot cards while the room is heated to induce trance
• D. Interpreting the body temperature changes of a subject during a session

Why: Hot reading relies on prior access to information about the target. Unlike cold reading, which uses observation during the session, hot reading depends on researching or obtaining details beforehand.

• A. The Barnum effect, also called the Forer effect ✓
• B. The sunk cost fallacy
• C. The confirmation bias cascade
• D. The availability heuristic

Why: The Barnum (Forer) effect describes people's tendency to accept vague, general personality descriptions as uniquely accurate. Psychics use it by offering broad statements that listeners eagerly fit to their own lives.

• A. Firing blank cartridges to startle the audience into a trance
• B. Making a rapid series of many different guesses so that some are likely to hit, then emphasizing the successful ones ✓
• C. Delivering a message at high volume to overcome skeptics
• D. Sending multiple mediums to the same sitting to cross-check details

Why: Shotgunning involves throwing out many specific statements at once. Given enough guesses, some will match, and the reader focuses on the hits while ignoring or quickly moving past the misses, creating an impression of accuracy.

• A. Psychic energy is weakened by laboratory equipment and fluorescent lighting
• B. Skeptics deliberately suppress psychic abilities through negative thinking
• C. Cold and hot reading techniques are eliminated when the reader cannot see the sitter, the sitter provides no feedback, and the information is blind-checked ✓
• D. Scientific instruments cannot detect the subtle signals that psychics transmit

Why: Controlled protocols remove the cues cold reading depends on, such as visual observation and verbal feedback, and prevent hot reading by withholding prior information. Under these conditions, claimed abilities typically perform at chance level, which suggests the apparent accuracy in ordinary sessions comes from these techniques.

• A. A conscious decision to move an object in a specific direction
• B. Unconscious muscle movements produced by expectations or suggestions, without awareness of the movement ✓
• C. A spirit's physical influence on objects in a room
• D. A reflex triggered by sudden changes in temperature

Why: The ideomotor effect describes small, unconscious muscle movements that occur in response to an idea or expectation. The person producing the movement is typically unaware they are doing it, which can make a planchette or pendulum appear to move on its own.

• A. Sigmund Freud, while studying hysteria in patients
• B. William Carpenter, while explaining table-turning and dowsing phenomena ✓
• C. Harry Houdini, while exposing fraudulent mediums
• D. Alfred Russel Wallace, while cataloguing spirit photographs

Why: The physiologist William Benjamin Carpenter described unconscious muscular action in the 1850s and used it to explain table-turning and similar séance phenomena. Later, psychologist William James and others expanded the concept.

• A. Spirits push it across the board when they are present
• B. The board contains hidden magnets that respond to ambient energy
• C. Participants' hands make tiny unconscious movements guided by expectation, and these add up to noticeable motion ✓
• D. The board's wood absorbs static electricity that moves the planchette

Why: Ideomotor movements by several participants, each small and unnoticed, can combine to move the planchette in directions no single person intends. Expectation of spirit control makes these movements more likely to be interpreted as supernatural.

• A. Asking the board questions whose answers are only known to the spirit world
• B. Having participants rest their fingertips lightly on the planchette while blindfolded or while listening to questions, then checking whether the answers match what they expected ✓
• C. Recording the session with a video camera to look for visible hand movements
• D. Holding the session in a darkened room to remove visual cues

Why: Blindfolding participants and having the experimenter control the questions removes the knowledge that would otherwise guide ideomotor responses. When answers become random or track only the experimenter's knowledge, the source is likely the participants' own unconscious movement rather than an external agent.

• A. It requires no evidence at all, making it easier to accept
• B. It explains the movement using a known, testable psychological mechanism, while spirit claims have no independent verification ✓
• C. It was endorsed by all major religious traditions
• D. Spirit explanations have been proven false in every case

Why: The ideomotor effect is a documented phenomenon that can be reproduced and tested in controlled conditions. Spirit explanations, by contrast, rest on claims that cannot currently be independently checked, so the ideomotor account is the more parsimonious and evidence-based explanation.

• A. A psychic's deliberate use of cold reading techniques to gather information from a client
• B. The tendency to accept vague or general statements as accurate because they seem personally meaningful to the listener
• C. A statistical method for checking whether a psychic's predictions came true more often than chance
• D. The process by which a medium verifies a message with the sitter's family before delivering it

• A. A reading that gives a precise date and name that later turn out to be correct
• B. A personality description such as 'You have a great need for other people to like you, yet you tend to be critical of yourself,' which most people rate as highly accurate
• C. A psychic who records all readings on video so that predictions can be checked later
• D. A medium who asks the sitter to confirm each detail before continuing

• A. It causes people to remember hits vividly and forget misses, so the apparent success rate appears higher than the actual one
• B. It makes people distrust any information that comes from a stranger, including accurate readings
• C. It forces psychics to make more predictions than they otherwise would
• D. It causes skeptics to deliberately reject all evidence presented to them

• A. It is too specific to be tested against any outcome
• B. It is so vague and multi-branched that almost any sitter can find a matching person, making a hit likely regardless of the psychic's ability
• C. Psychics are legally forbidden from mentioning names
• D. It relies entirely on the sitter's own statements, so no information is transferred

• A. Asking the psychic to explain how their abilities work
• B. Recording predictions in advance and comparing them with outcomes, including misses, under controlled conditions such as double-blind testing
• C. Relying on testimonials from satisfied clients
• D. Trusting the psychic's own estimate of their accuracy rate

• A. 1 in 2
• B. 1 in 5 ✓
• C. 1 in 10
• D. 1 in 25

Why: With five equally likely symbols (circle, cross, wavy lines, square, star), each guess has a 1 in 5 (20%) chance of being correct by chance alone. Researchers compare observed hit rates against this baseline to see whether results exceed what chance predicts.

• A. To make the experiment more entertaining for participants
• B. To ensure the target cannot be predicted or inferred by the participant or experimenter ✓
• C. To increase the number of trials needed for statistical significance
• D. To allow the sender to choose targets based on their intuition

Why: If targets are predictable or can be inferred through normal cues, apparent success may reflect sensory leakage or experimenter bias rather than extrasensory perception. Proper randomization closes these alternative explanations, so that any above-chance performance must be explained some other way.

• A. A failure of the participant's equipment during testing
• B. Unintended normal sensory cues that allow a participant to identify targets without any extrasensory ability ✓
• C. The loss of data when records are not properly stored
• D. The tendency of participants to forget their guesses over time

Why: Sensory leakage refers to ordinary channels such as hearing a sound, glimpsing a reflection, or noticing a change in the experimenter's breathing that could reveal the target. Early ESP experiments were often criticized because such leakage was not adequately controlled, which is why later studies used sound-proofed, isolated conditions.

• A. It doubles the number of trials so results are more reliable
• B. It prevents both the participant and the person recording the responses from knowing the correct target during the trial, reducing unintentional cueing and recording bias ✓
• C. It requires two participants to agree on every guess
• D. It ensures that the target is shown twice to the participant

Why: In a double-blind design, neither the participant nor the experimenter who scores responses knows the target until after the guess is recorded. This prevents subtle cues, such as facial expressions or tone of voice, and scoring errors from influencing results.

• A. 20
• B. 40 ✓
• C. 60
• D. 100

Why: Expected chance hits equal the number of trials multiplied by the probability of success on each trial: 200 × 1/5 = 40. The observed 60 hits exceeds this baseline, but whether the difference is statistically significant depends on the variance, which a binomial test would assess. Above-chance results alone do not establish ESP without ruling out methodological flaws.

• A. Confirmation bias
• B. Selective memory (hit-and-miss memory bias) ✓
• C. Anchoring bias
• D. Dunning-Kruger effect

Why: Selective memory, often called the hit-and-miss effect, causes people to recall the statements that seemed accurate while forgetting the many that were wrong. This makes a psychic's overall record seem far more impressive than it actually is.

• A. The tendency to believe vague, general personality descriptions apply specifically to oneself ✓
• B. The tendency to predict future events based on past patterns
• C. The tendency to disbelieve information that contradicts existing views
• D. The tendency to rate ambiguous images as more meaningful in groups

Why: In 1948, psychologist Bertram Forer gave students a personality sketch of mostly generic statements and found most rated it as highly accurate. Psychics often use similar broad statements that nearly everyone can relate to.

• A. They have access to secret government databases
• B. They use subtle verbal and visual cues from the sitter, combined with probability and leading questions ✓
• C. They are genuinely receiving information from spirits
• D. They prepare detailed files on every client beforehand

Why: Cold reading relies on observing body language, clothing, and speech, then making guesses and using the sitter's reactions to refine them. Statements are phrased so that the sitter supplies the specific meaning, creating the impression of hidden knowledge.

• A. It ensures the psychic's predictions are recorded and checked later
• B. The sitter's nods and reactions guide the psychic to continue on productive lines, while silence or disagreement prompts a change of direction ✓
• C. It allows scientists to measure psychic energy in real time
• D. It requires the psychic to repeat the same reading to every client

Why: Psychics continuously read facial expressions and verbal responses, reinforcing hits and quietly abandoning misses. Because the sitter's own reactions shape the session, the psychic appears to be getting increasingly accurate even without any real information.

• A. Hits are always caused by fraud
• B. With many vague statements and a large population of people, some matches are expected by chance alone, and dramatic hits are often remembered while countless misses are forgotten ✓
• C. Psychic abilities only work occasionally, so one hit is meaningless
• D. Only scientists can verify whether a hit is genuine

Why: Given enough guesses and enough people, coincidental matches are statistically inevitable. Without recording all predictions, including misses, and comparing results to chance, a memorable hit tells us little about actual ability.