Pub. date: 2010 | Online Pub. Date: December 16, 2009 | DOI: 10.4135/9781412972000 | Print ISBN: 9781412940818 | Online ISBN: 9781412972000| Publisher:SAGE Publications, Inc.About this encyclopedia
Hallucinations and Altered Perceptions
Sensory percepts may sometimes occur in the absence of adequate sensory stimulation. The most prominent examples of nonveridical percepts are hallucinations. They can be pathological, but can also affect healthy individuals. Nearly 10% of the general population reported having experienced an unexplained perception; about 3% reported having heard a voice. Hallucinations may result in secondary delusions —inaccurate explanations of what is happening. This entry discusses hallucination in healthy people, in mental disorders, and in other medical conditions; other altered perceptions; nonveridical percepts in everyday life; and neuronal mechanism of nonveridical perceptions. Healthy people can experience hallucinations. For instance, the hearing of a family member's voice is not uncommon among recently bereaved people. These hallucinations become less frequent and cease over weeks or months. They are comforting and benign. Some people take hallucinogenic drugs, such as LSD or mescaline, with the clear intention of inducing hallucinogenic experiences. Hallucinations may also occur ...