D elusions can vary both thematically and in scope. The delusions of some individuals are tightly circumscribed; for example, a person with “Capgras” delusion may believe that a loved one (usually a spouse or close relative) has been replaced by a physically identical impostor, but be mentally lucid in seemingly all other respects. More remarkable still is the phenomenon of “perceptual delusional bicephaly,” exemplied by the case of a man who believed that he had two heads, the second of which belonged to his late wife’s gynecologist. This patient was unfortunately hospitalized with gunshot wounds after attempting to remove the second head violently. He had initially planned to attack it with an ax (Ames, 1984).