Animist thinking in the elderly and in patients with Alzheimer's disease.

Some patients with Alzheimer's disease (AD) reveal low-level impairment in their concepts of living things (i.e., forgetting that zebras are striped). To test for more profound impairment, we investigated the concept alive--a "higher order" concept spanning every member of the domain. Many elderly controls were animists, attributing life to inanimates capable of self-generated activity (the sun, fire). Most AD patients were animists, with half even attributing life to inanimates whose activity is not self-generated (cars, lamps). Adult animists, like young children who have not yet acquired biological concepts, overattributed life to active inanimates. We believe this reflects an innate disposition to view active entities as agents, and that agency interferes with the biological concept alive. This interference, we suggest, reflects degradation of biological concepts in the face of spared perception of agents. It sheds light on the nature of fundamental questions concerning conceptual organization, innate endowment, and conceptual change.