A patient describes a hallucinatory perception. Before revealing the answer, decide what specifically distinguishes an extracampine hallucination from a hallucination more generally.

Ask specifically about the spatial location of the perceived stimulus relative to what the relevant sense organ could physically detect from that position. An extracampine hallucination differs from an ordinary hallucination only in this one specific respect: the impossible location of the perceived stimulus, not in its perceptual quality, conviction, or any other feature. Most often described for vision, such as seeing something behind the head, or hearing, such as a voice from an impossibly distant location, this spatial impossibility is the single detail that separates the extracampine form from hallucination in general, and the patient may or may not spontaneously notice this impossibility themselves.