Thirteen days: Joseph Delboeuf versus Pierre Janet on the nature of hypnotic suggestion

Abstract The problem of post‐hypnotic suggestion was introduced in 1884. Give a hypnotic subject thepost‐hypnotic command to return in 13 days. Awake, the subject remembers nothing yet nonetheless fulfillsthe command to return. How then does the subject count 13 days without knowing it? In 1886, Pierre Janetproposed the concept of dissociation as a solution, arguing that a second consciousness kept track of timeoutside of the subject's main consciousness. Joseph Delboeuf, in 1885, and Hippolyte Bernheim, in 1886,proposed an alternative solution, arguing that subjects occasionally drifted into a hypnotic state in which theywere reminded of the suggestion. This article traces the development of these competing solutions and describessome of Delboeuf's final reflections on the problem of simulation and the nature of hypnosis. © 2004Wiley Periodicals, Inc.