Johns Hopkins Psychiatry Guide

Hallucinations

Traci Speed, M.D., Ph.D., Thomas Sedlak, M.D., Ph.D.
Hallucinations is a topic covered in the Johns Hopkins Psychiatry Guide.

To view the entire topic, please or purchase a subscription.

Johns Hopkins Guides provide diagnosis, management, and treatment guidance for infectious diseases, diabetes, and psychiatric conditions. Explore these free sample topics:

Johns Hopkins Guides

~~ The first section of this topic is shown below ~~

DEFINITION

  • An hallucination is a perception without a stimulus.
    • With true hallucinations, the individual is convinced of the reality of the experience.
  • A true hallucination must be differentiated from:
    • Illusion - a misinterpretation of a stimulus (e.g., a crack on the floor is misperceived as a snake)
    • Pseudohallucination - occurs in inner subjective space (e.g., heard in one’s thoughts, not perceived as auditory, does not come through the ears)
    • Vivid imagery – increased imagination or mental images
  • Hallucinations can occur in any of the five senses (auditory, visual, olfactory, gustatory, and/or tactile).
    • Auditory hallucinations are the most common.
  • Hallucinations are not pathognomic for any specific psychiatric illness, including schizophrenia [1].
  • Hypnagogic and hypnopompic hallucinations can occur in healthy people when falling asleep and awakening, respectively.

~~ To view the remaining sections of this topic, please
or purchase a subscription ~~

Last updated: December 5, 2014