A skilled hypnotist can deliberately produce or prevent hypnotic amnesia in a subject, but effectiveness depends on the subject’s susceptibility, the suggestions used, ethical limits, and context (therapeutic vs. experimental).
Explanation and important details
What “hypnotic amnesia” is
Hypnotic amnesia refers to a temporary inability to recall material that was learned, experienced, or suggested while under hypnosis (or just before it), usually produced by a posthypnotic suggestion such as “You will not remember anything from this session until I say the word ‘apple.’” The amnesia is typically reversible (recall returns when the cue is given or after termination of the suggestion) and is different from organic memory loss.
Can it be produced deliberately?
Yes. Hypnotists routinely use posthypnotic or post-trance suggestions to block recall of specified material. Laboratory studies and clinical practice show that:
Highly suggestible individuals are much more likely to exhibit robust hypnotic amnesia.
Suggestions that are clear, specific, and delivered while the subject is deeply hypnotized work best.
Amnesia can be for particular events, for content of the session, or for certain words, images, or experiences.
Classical experimental paradigms (e.g., Hilgard, Bowers, later cognitive-neuroscience studies) demonstrate reliable induction of amnesia for words, lists, or autobiographical material in responsive subjects.
Can a hypnotist prevent or reverse hypnotic amnesia?
Yes. A hypnotist can give suggestions that prevent amnesia (for example, instructing the subject to remember everything) or later remove a previously given amnesia suggestion (reversal cue, deactivation, or posthypnotic “recall” suggestion). Empirical findings:
A suggestion to remember counteracts an earlier suggestion to forget, especially in more suggestible people.
Specific recall cues (a word, a gesture) reliably restore memory if the amnesia was suggestion-based.
If the subject resists or is not sufficiently responsive, prevention or reversal may fail or be partial.
Mechanisms and variability
Mechanisms are not “erasing” memory traces; rather, suggestion changes access to the memory (retrieval) and the subject’s introspective/reporting. Neuroimaging shows changes in brain regions involved in memory retrieval and executive control during hypnotic amnesia.
Individual differences: hypnotizability (scale scores), motivation, trust in the hypnotist, expectations, and the nature of the material all influence outcome.
Not all subjects: Low-suggestibility people often show little or no hypnotic amnesia; some highly suggestible people show very strong, reversible effects.
Limits, risks, and ethics
Ethical practice requires informed consent. Deliberately causing amnesia outside an agreed therapeutic or research context is unethical.
Hypnotic amnesia is generally temporary. Long-term permanent amnesia is not reliably produced by suggestion alone.
Suggestion can sometimes produce confabulation or altered reports — so memory retrieved under hypnosis may be distorted.
In forensic contexts, hypnotically induced amnesia or memory enhancement/removal is controversial; courts often treat such memory as unreliable.
Practical examples
Produce: During trance say, “After you wake, you will not remember anything I say for the next hour.” Many responsive subjects will report no recall until a specified cue.
Prevent: Before presenting material say, “You will remember everything I say today and will have perfect recall after waking.” This often reduces or eliminates hypnotically induced forgetting.
Reverse: After inducing amnesia, give a posthypnotic cue such as “When I snap my fingers you will remember everything” — many subjects will recover recall on the cue.
Evidence base (brief)
Classic experimental work (e.g., Ernest Hilgard) and numerous cognitive-neuroscience studies confirm the phenomenon and its modifiability by suggestion. Modern neuroimaging shows correlates in prefrontal and medial temporal systems when amnesia is suggested versus when recall is allowed.