Hallucinations are defined as

• A. False beliefs despite proof
• B. Perceptions in the absence of external stimuli
• C. Distorted interpretation of real stimuli
• D. Imagined sensations only in sleep

Answer: (B)

Hallucinations are sensory experiences that seem real but occur without any actual external input. They can involve any sense—hearing voices (auditory), seeing people or things (visual), smelling odors (olfactory), tasting flavors (gustatory), or feeling sensations on the skin (tactile)—and they can occur while a person is awake. This is what makes them “perceptions in the absence of external stimuli.”

Delusions, by contrast, are false beliefs held with conviction despite clear evidence to the contrary. Illusions are misperceptions of real external stimuli (a rope seen as a snake in dim light, for example). Imagined sensations limited to sleep describe dream imagery or hypnagogic experiences, which are not hallucinatory experiences occurring while awake.