Covert hypnosis refers to an attempt to communicate with another person's unconscious mind without that person noticing. As it often takes place in the course of a seemingly regular conversation, it is also known as conversational hypnosis or sleight of mouth. The objective is to change the person’s behavior subconsciously so that the target believes that they changed their mind of their own volition. When performed successfully, the target is unaware that they have been hypnotized or that anything unusual has occurred.
Covert hypnosis is a phenomenon not too different from indirect hypnosis, as derived from Milton H. Erickson and popularized as "The Milton Model" in style,  but the defining feature is that the hypnotized individual subsequently engages in hypnotic phenomena without conscious effort or choice. Covert hypnosis, like "Ericksonian Hypnosis",[clarification needed] "operates through covert and subtle means... to reach deeper levels of consciousness than are touched by the surface structure of language". It is the concept that an individual, 'the hypnotist,' can control another individual's behavior via gaining rapport.  During hypnosis, the operator (hypnotist) makes suggestions. The subject is intended to not be completely aware, on a conscious level, of the manipulation.
The hypnotist gains rapport  with the listener(s) and the hypnotist maintains psychological congruency  (the act of truly acting towards your goals without hesitation[clarification needed]), both linguistically and in one's nonverbal communication. As the subject listens while feeling a psychological connection with the hypnotist and the hypnotist displaying behaviors such as confidence and understanding, the hypnotist then presents linguistic data in the form of metaphor:
- "The Metaphor presents a surface structure of meaning in the actual words of the story, which activates an associated deep structure of meaning that is indirectly relevant to the listener, which activates a recovered deep structure of meaning that is directly relevant to the listener."
 In other words, this process builds most likely unconscious states within the listener, and then associates those states through covert conditioning, also known as covert anchoring, thereby forming unconsciously controlled behaviors and thoughts. Often methods of tricking the listener to believe that the hypnotist is talking about something else other than the subject are employed, for instance, by shifting use of time and use of identity in language. One famous example is employed by Milton H. Erickson "and a tomato can be happy".
A state of forgetfulness can be elicited by talking about what it feels like to be in that state in a manner that implies the other person is currently experiencing it. Once this state is at a heightened peak the hypnotist can then talk about that state relating to a concept like the unsuspecting subject's name (a phenomenon called name amnesia), and the subject will suddenly be unaware of his/her name on questioning (provided the suggestions implied immediate effect and the reader is suggestible enough to be influenced in this way). The purpose of covert hypnosis is to shut down or at least reduce the use of analytical mind in a person. This can be achieved fairly quickly by someone with practice.
Covert hypnosis in the media
Real estate trainer Glenn Twiddle in June 2010, appeared on the Australian television show A Current Affair. The segment explains how he teaches real-estate agents these techniques to use on unsuspecting buyers of property.
- Nathan Blaszak (2004). How To Hypnotize Anyone Without Getting Caught. Life Tricks Inc. pp. 1–250.
- Kevin Hogan (2006). Covert Hypnosis: An Operator's Manual. Network 3000 Publishing. p. 232. ISBN 0-9709321-4-6.
- Kevin Hogan and James Speakman (2006). Covert Persuasion: Psychological Tactics and Tricks to Win the Game. Wiley. p. 223. ISBN 0-470-05141-8.
- Glenn Twiddle (2010). Advanced Hypnotic Selling. Glenn Twiddle Publishing. p. 136. ISBN 978-0-9807711-0-7.
- Dilts, Robert (1999). Sleight of Mouth: The Magic of Conversational Belief Change. ISBN 0-916990-43-5.
- Robert B. Dilts; Judith A. Delozier (2000). "776 MiltonModel" (Online encyclopedia). Encyclopedia of Systemic Neuro-Linguistic Programming and NLP New Coding. NLP University Press. Retrieved 21 May 2012.
- Erickson, Milton H. (December 1976). Hypnotic Realities: The Induction of Clinical Hypnosis and Forms of Indirect Suggestion.
- Cohen, Michael H. A Question of Time. p. 8.
- Trancework: An Introduction to the Practice of Clinical Hypnosis. p. 37.
- Haley, Jay. Uncommon Therapy. ISBN 0-393-31031-0.
- Gavin, James. Lifestyle Fitness Coaching. p. 41.
- Robert Norton and David Brenders. Communication and Consequences: Laws of Interaction. p. 207.
- Geoff Shearer (9 June 2010). "Real estate agents use hypnosis to seal property deals". The Courier Mail. Retrieved 21 May 2012.