Glossary
The key terms of hypnosis and research, explained simply.
- Induction
- The starting phase of hypnosis, in which the practitioner guides the person toward this state of focused attention, often with suggestions of relaxation and focus.
- Suggestion
- A proposal made during hypnosis, for example “your hand is becoming light”, experienced more directly and more automatically than usual. It is the core ingredient of hypnosis.
- Hypnotic suggestibility (or hypnotisability)
- The individual ease of responding to hypnotic suggestions. It is measured with standardised scales and varies widely from one person to another.
- Altered state of consciousness
- A way of functioning mentally that differs from ordinary wakefulness, without being sleep. Depending on the researchers, hypnosis is one, or is explained by ordinary mental processes (see “state and non-state theories”).
- Trance
- A common term for the hypnotic state. It can be misleading, as it wrongly suggests a loss of consciousness or control.
- Self-hypnosis
- The ability to enter hypnosis on your own, without a practitioner, usually learned in session and then practised alone, for example to manage stress or pain.
- Hypnotherapy
- The use of hypnosis in addressing a medical or psychological condition. It is a technique in the service of care, not a treatment in itself.
- Hypnoanalgesia
- The use of hypnosis to reduce pain, for example during a procedure, an examination or childbirth, alongside or sometimes partly replacing painkillers.
- “State” and “non-state” theories
- The scientific debate over the nature of hypnosis. “State” theories see it as a genuine altered state of consciousness; “non-state” theories explain it through ordinary processes such as attention, imagination and expectations.
- Pseudo-memory (false memory)
- A memory that feels real but does not match what actually happened. Hypnosis can encourage such memories, which makes it unsuitable for recovering reliable memories.
- Placebo effect
- A real improvement linked to expectations and the care context, rather than to the treatment itself. In research, it is distinguished from the specific effect of hypnosis.
- Randomised controlled trial (RCT)
- A study that compares a group receiving the intervention with a control group, with participants assigned at random. It is one of the most reliable ways to test whether something truly works.
- Systematic review
- A study that gathers and appraises, using a rigorous method, all existing research on a question, to draw a more robust overall picture than any single study.
- Meta-analysis
- A systematic review that statistically combines the results of several studies to estimate a more precise overall effect.
- Level of evidence
- A way of situating the strength of the data behind a claim. On this site, three markers: established (solid, converging evidence), promising (encouraging results to be confirmed), exploratory (early data, to interpret with caution).
- MRI (magnetic resonance imaging)
- A machine that images the brain. In its “functional” form (fMRI), it tracks blood flow to locate, indirectly, the most active areas.
- PET (positron emission tomography)
- An imaging technique that measures brain activity using a mildly radioactive tracer that follows energy use or blood flow.
- EEG (electroencephalography)
- A device that measures the brain’s electrical activity using electrodes placed on the scalp.
- Anterior cingulate cortex
- A deep, midline brain region. It detects conflict and effort, and contributes to the unpleasant side of pain. A kind of alarm system.
- Dorsolateral prefrontal cortex
- At the front of the brain, on the sides. The core of the network that steers voluntary attention and concentration, often called “the conductor”.
- Default mode network
- A set of regions that activate together when we are not doing anything in particular: daydreaming, self-reflection, rumination. Its front part often quiets down under hypnosis.
- Insula
- A region tucked deep in the brain that receives the body’s internal state (heart, breathing, pain). The seat of internal-sensation perception.
- Primary somatosensory cortex
- The area that receives and locates body sensations: touch, the intensity of a stimulus. The “basic” sensory area.
- Functional connectivity
- A measure of how much two regions “work together”: their activity rises and falls in a coordinated way. A connection can strengthen or loosen.
- Double dissociation
- A situation where action A changes X without affecting Y, and action B changes Y without affecting X. Strong evidence that X and Y are independent.