Delusional misidentification of inanimate objects: a literature review and neuropsychological analysis of cognitive deficits in two cases

Following a brief review of the literature on Delusions of Inanimate Doubles (DID), compared with other similar delusions, two cases are presented. Each completed a battery of tests designed to explore their cognitive abilities. In both cases, familiar and unfamiliar face-processing skills remained intact and word memory was unaffected. Their abilities to identify famous buildings and recognise unfamiliar houses were impaired. We propose that an extension of Ellis and Young's (1990) account of Capgras delusion can explain the cognitive impairments in case of DID. A comparison of the hypotheses of Staton et el. (1982), Ellis and Young (1990), and Van Lancker (1991) is also made. The last two have obvious similarities and seem to provide the best general approach. Finally, we caution the need to consider how a mood of suspiciousness may be needed to distort attribution processes that sustain delusional thinking.