Suggestion is the psychological process by which a person guides their own or another person's desired thoughts, feelings, and behaviors by presenting stimuli that may elicit them as reflexes instead of relying on conscious effort.

Nineteenth-century writers on psychology such as William James used the words "suggest" and "suggestion" in the context of a particular idea which was said to suggest another when it brought that other idea to mind. Early scientific studies of hypnosis by Clark Leonard Hull and others extended the meaning of these words in a special and technical sense (Hull, 1933).

The original neuropsychological theory of hypnotic suggestion was based upon the ideomotor reflex response that William B. Carpenter declared, in 1852, was the principle through which James Braid's hypnotic phenomena were produced.