Historical Perspective on Hallucinations

Lavater introduced "hallucination" in the English language in 1572 to refer to "ghostes and spirites walking the nyght". The word was first used in its current sense by Jean Etienne Esquirol in 1837.

Descriptions of hallucinatory phenomena have figured prominently in written documents since the beginning of recorded history.

In the Middle Ages, hallucinations were thought to be manifestations of demons or angels. A religious person who experienced such phenomena was seen as a saint, whereas a commoner was believed to be possessed by the devil. In certain cultures today, hallucinations are still perceived as the work of Satan or as a result of magic (Wahass & Kent, 1997).

Normally, hallucinations are perceptions that occur in the absence of corresponding sensory stimuli. From the subjective point of view of the individual who experiences these phenomena, they are indistinguishable from normal perceptions. Something is perceived yet, objectively, there is nothing to perceive. In this sense, hallucinations are different from illusions, which are distortions or misperceptions of a perceivable object. However, people having hallucinations are confronted to other people dismissing their perceptions. Therefore, the estimation of hallucinations in the general population is based on people having experienced perceptions not confirmed by others.

In the general population, using the data from the NIMH epidemiological catchment area survey, Tien (1991) found an incidence of visual hallucinations of 2% among men and 1.3% among women.

In a comparative study of hallucinations in the general population and among schizophrenics, Lindal et al. (1994) observed that the former mainly reported visual hallucinations involving persons, whereas the latter were more likely to report other types of hallucinations. However, schizophrenia is relatively infrequent in the general population.

In the United States, the Epidemiological Catchment Area study (Regier et al., 1988) found a lifetime prevalence of schizophrenia of 1.5%.

This prevalence was 0.7% in the National Comorbidity Survey (Kendler et al., 1996). An Israeli survey found a prevalence of 0.7% in individuals aged 35-45 years (Levav et al., 1993).

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