Which best describes a hallucination?

A hallucination is defined as a sensory experience that occurs in the absence of an actual external stimulus. Therefore, the best description of a hallucination is that it represents a sensory experience of something that does not exist outside the mind. This means that individuals who experience hallucinations perceive things—such as sounds, sights, or sensations—that are not present in the real world, and these experiences are linked to various psychological or neurological conditions.

Hallucinations might manifest in different forms, such as auditory (hearing voices), visual (seeing things that aren't there), or other sensory modalities. The nature of these experiences hinges on them being internally generated rather than a reflection of any shared reality, which supports the idea that they exist solely within the individual's mind.

The other options fail to encompass the essential characteristics of hallucinations. While some might involve sensory distortions, they do not capture the fundamental aspect that hallucinations exist with no basis in external reality. Thus, recognizing hallucinations as experiences rooted solely in the mind is key to understanding their definition and significance in fields such as psychology and drug recognition.