Also known as hygric sensation. Both terms are indebted to the Greek noun hugros, which means humidity. They are used to denote a hallucination of water or other fluids, perceived in the tactile modality. Accordingly, the German psychiatrist and philosopher Karl Jaspers (1883-1969) classifies hygric hallucinations as a subclass of the " haptic hallucination. The British neurologist Macdonald Critchley (1900-1997), by contrast, classifies them as a type of "dysaesthesia. Hygric hallucinations may be experienced as cold, tepid, warm, or hot. They have been reported in the context of the use of "hallucinogens such as LSD and mescaline, but also in "aural phenomena preceding paroxysmal neurological disorders such as migraine and epilepsy. The term hygric hallucination should not be confused with the term " waterfall illusion.
References
Critchley, M. (1953). The parietal lobes. London: Edward Arnold & Co.
Jaspers, K. (1997). Generalpsychopathology. Volume 1. Translated by Hoenig, J., Hamilton, M.W. Baltimore, MA: Johns Hopkins University Press.
Dictionary of Hallucinations. J.D. Blom. 2010.