Hallucinate

Hallucinate is the perception of a sensory experience without an external stimulus that corresponds to that experience. The term is most commonly used in psychology, psychiatry, and neurology to describe phenomena in which individuals see, hear, smell, taste, or feel something that is not present in the environment. Hallucinations can occur in any sensory modality, though visual and auditory forms are the most frequently reported.

Causes of hallucinations are diverse and include neurological disorders such as Parkinson’s disease, epilepsy, and dementia; psychiatric conditions such as schizophrenia and bipolar disorder; substance use, particularly with psychedelics, stimulants, alcohol withdrawal, and certain prescription medications; and physiological states like sleep deprivation, fever, or sensory deprivation. Cultural and religious practices may also involve intentional induction of hallucinatory states through meditation, chanting, or the use of psychoactive plants.

Hallucinations are classified by content (simple versus complex), modality (visual, auditory, olfactory, gustatory, tactile, or multimodal), and by their relationship to reality (pseudohallucinations are recognized by the experiencer as unreal). In clinical settings, the presence, frequency, and distress associated with hallucinations help guide diagnosis and treatment, which may involve antipsychotic medication, cognitive‑behavioral therapy, or addressing underlying medical conditions.

Research into the neural mechanisms of hallucination has contributed to broader understanding of perception, consciousness, and brain connectivity, highlighting the brain’s capacity to generate experiences independent of external input. Related concepts include illusion, delusion, and perception.