You suspect a patient may hold a Capgras-type delusion about a family member. Which single question would most usefully help confirm this specific pattern, rather than a more general sense of unfamiliarity?

Directly asking whether the person's appearance looks exactly right is the key question, since Capgras syndrome is specifically defined by acknowledging perfect physical resemblance while rejecting the underlying identity — a more general question about the relationship or sleep would not surface this specific, structured delusional pattern.

Key discriminating feature: The defining feature of Capgras syndrome is that the physical resemblance is acknowledged as perfect while the underlying identity is rejected, so directly asking whether the appearance itself looks right is what separates this specific delusion from a more general, less structured sense of unfamiliarity.

Common misconception: Assuming the belief must involve a change in the person's actual appearance risks missing the specific, defining feature of Capgras syndrome: perfect acknowledged resemblance combined with rejection of identity.