Conversational hypnosis was a concept largely devised and attributed to an American psychiatrist by the name of Milton Erickson. Erickson founded the American Society for Clinical Hypnosis and was best known for his theories concerning the unconscious mind and how it is susceptible to suggestion in ways that our conscious minds are not.

Probably the single most important concept defined by Erickson was the trance theory. He believed the unconscious mind is always listening, and that while in a trance state, a subject is receptive to things that they would not normally be receptive to. This is a form of indirect suggestion, and the susceptibility comes by inducing a hypnotic trance.  It is important to note that conversational hypnosis is not mind control, but rather a form of influencing people through conversation alone.  There is no taking over a person's thoughts or actions in this process.  Free will is maintained.

Trance as defined by Erickson is an everyday occurrence that happens any time we are intensely focused on something. Trance is a state of concentration rather than zoning out or being mindless. It is when we are thinking so much about one particular thing that all our mind's energy is focused there, putting us in a more receptive state.

While trance by this definition makes us more vulnerable (to suggestion, at least), it also allows us to focus and concentrate much better than we can in normal frames of mind. Erickson's conversational hypnosis techniques have been employed and written about by many hypnotists and scholars around the world.

Conversational hypnosis is no longer a secret concept that normal people can't learn, but is rather becoming accessible to anyone regardless of psychological or hypnotic experience.