A patient reports a real stimulus is being perceived abnormally. Before revealing the answer, decide what distinguishes sensory intensity distortion from an illusion.

Ask whether the identity of the stimulus itself is being misperceived, or only its strength. Sensory intensity distortion differs from an illusion, in which a real stimulus is misperceived as something else entirely, rather than merely perceived as louder, brighter, or quieter than it truly is — the identity and nature of the stimulus remains correctly recognised, and only its felt intensity is altered. An illusion, by contrast, involves a real stimulus being perceived as something categorically different from what it actually is, such as a coat on a hook being misperceived as a person. Whether the stimulus's identity is correctly recognised, with only its intensity distorted, versus the stimulus itself being misperceived as something else entirely, is the key distinguishing feature.