Knowra Hallucination Hallucination A perception-like experience occurring without a corresponding external stimulus. Hallucinations can involve any sensory modality and may occur in health conditions, during sleep transitions, or under other circumstances.
Illusion : A misperception of an existing external stimulus. Unlike hallucinations, illusions distort something present in the environment.
Predictive processing : A theory that perception combines sensory input with predictions generated by the brain. Overweighted predictions may produce perception-like experiences when incoming evidence is insufficient.
Visual hallucination : The perception of images, forms, or scenes without corresponding visual stimuli. This sensory form ranges from simple flashes to detailed scenes.
Psychosis : A mental state involving impaired contact with reality, which may include hallucinations or delusions. Hallucinations can occur during psychosis, but their presence alone does not establish it.
Delusion : A firmly held belief that persists despite strong contradictory evidence. Hallucinations are perceptual experiences; delusions are beliefs, though they can occur together.
Source monitoring : The cognitive process of identifying the origin of memories, thoughts, and perceptions. Mistaking internally generated content for external input is one proposed route to hallucination.
Olfactory hallucination : The perception of odors without a corresponding odor source. Smell experiences illustrate hallucinations beyond the more commonly discussed voices and images.
Schizophrenia : A psychiatric disorder involving symptoms such as psychosis, disorganization, and changes in motivation or cognition. Hallucinations, especially voices, can be part of schizophrenia’s clinical presentation.
Pseudohallucination : A vivid perception-like experience recognized as arising in the mind rather than external reality. The term marks experiences that resemble hallucinations but retain insight into their internal origin.
Auditory verbal hallucination : The experience of hearing speech or voice-like sounds without an external speaker. Voice-hearing is a well-studied specific form of hallucination.
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