Eric Eich University of British Columbia
The idea that what has been learned in a certain state of mind or brain is best remembered in that state is an old and familiar one in psychology. The credit for this concept--one that I refer to as state dependent memory--goes to an astute French aristocrat, the Marquis de Puységur ( Chastenet de Puységur, 1809; Ellenberger , 1970). In 1784, Puységur discovered that although a person might appear, upon awakening, to be amnesic for events that had occurred during hypnosis, memory for these events returned once the individual reentered a state of "magnetic sleep"--Puységur's term for hypnosis. Decades later, a French physician named Azam ( 1876) related a strikingly similar observation in connection with the case of a young woman who suffered sudden attacks of hysterical somnambulism, or "pathological sleep," as the disorder was then known. And in an article published in 1910, Morton Prince conjectured that the reason most people have difficulty remembering their dreams is not because they do not want to remember--as Freud ( 1953) and other psychodynamicists of the day were claiming--but rather, because they cannot remember, owing to the dissimilarity between the states of "natural sleep" and ordinary wakefulness.
Like psychology itself, the concept of state dependent memory has a long past, but a short history as a subject of scientific study. Indeed, the earliest experimental demonstrations of human state dependence date only to the late 1960s (see Eich, 1977; Weingartner, 1978), and of the 100-plus empirically oriented articles of the subject that have appeared since then, approximately 70% have been published within the last 10 years.
During the first decade of research on human state dependent memory, from about 1967 to 1976, almost all experiments dealt with drug-defined differences in state. This type of experiment is exemplified by the work of Goodwin, Powell,