Among Erickson’s best-known innovations is the hypnotic handshake induction, which is a type of confusion technique. The induction is done by the hypnotist going to shake hands with the subject, then interrupting the flow of the handshake in some way, such as by grabbing the subject’s wrist instead. If the handshake continues to develop in a way which is out-of-keeping with expectations, a simple, non-verbal trance is created, which may then be reinforced or utilized by the hypnotist. All these responses happen naturally and automatically without telling the subject to consciously focus on an idea.
This induction works because shaking hands is one of the actions learned and operated as a single “chunk” of behavior; tying shoelaces is another classic example. If the behavior is diverted or frozen midway, the person literally has no mental space for this - he is stopped in the middle of unconsciously executing a behavior that hasn’t got a “middle”. The mind responds by suspending itself in trance until either something happens to give a new direction, or it “snaps out”. A skilled hypnotist can often use that momentary confusion and suspension of normal processes to induce trance quickly and easily.
Any habitual pattern which is interrupted unexpectedly will cause sudden and light trance. The handshake is a particularly good pattern to interrupt because the formality of a handshake is a widely understood set of social rules. Since everyone knows that it would be impolite to comment on the quality of a handshake, regardless of how strange it may be, the subject is obliged to embark on an inner search (known as a transderivational search, a universal and compelling type of trance) to identify the meaning or purpose of the subverted pattern.