HALLUCINATION. — A purely subjective perception, not corresponding to any external objective reality; the individual projects outside himself images existing in his mind with such vividness as to believe them truly to exist externally. Thus he sees things, animals, people; hears noises and voices; tastes flavours; has tactile impressions that exist only in his imagination. Hallucination may be causally linked to intoxications from alcohol (zoopsies of alcoholics), cocaine, hashish, etc.; infectious diseases, particularly those with high fever; it is a common feature of serious mental illnesses (epilepsy, general paralysis of the insane, schizophrenia, paranoia, manic-depressive forms); in persons with over-excitable imagination it may occur at the moment of drowsiness. A serious disturbance of the cognitive faculty, hallucination powerfully influences the practical activity of the subject, who is driven to act in accordance with impressions he believes to be real, performing actions and resorting to acts of offence or defence whose motivation, of purely subjective logic, ordinarily does not imply his moral responsibility.
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