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a sensory impression (sight, touch, sound, smell, or taste) that has no basis in external stimulation. Hallucinations can have psychologic causes, as in mental illness, or they can result from drugs, alcohol, organic illnesses, such as brain tumor or senility, or exhaustion. When hallucinations have a psychologic origin, they usually represent a disguised form of a repressed conflict. adj. adj hallu´cinative, hallu´cinatory.
auditory hallucination a hallucination of hearing; the most common type.
gustatory hallucination a hallucination of taste.
haptic hallucination tactile hallucination.
hypnagogic hallucination a vivid, dreamlike hallucination occurring at sleep onset.
hypnopompic hallucination a vivid, dreamlike hallucination occurring on awakening.
kinesthetic hallucination a hallucination involving the sense of bodily movement.
olfactory hallucination a hallucination of smell.
somatic hallucination a hallucination involving the perception of a physical experience occurring within the body.
tactile hallucination a hallucination of touch.
visual hallucination a hallucination of sight.
false perception of movement or sensation, as from an amputated limb, or crawling sensation on the skin.
A false sense of touching something or of objects moving on the skin. This abnormal perception is a hallmark of some withdrawal states, such as delirium tremens in alcohol withdrawal. See: formication
See also: hallucination