folie à deux

a rare psychotic disorder in which two intimately related individuals simultaneously share similar or identical delusions (French, “double insanity”). It is the most common form of shared psychotic disorder. Rarer forms involving more than two intimately related individuals or members of the same family are called folie à trois (a delusion shared by three people), folie à quatre (a delusion shared by four people), and so on.

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Psychology term of the day

January 5th 2025

common region

a recently introduced gestalt principle of organization, stating that objects sharing a common bounded region of space appear to belong together and tend to be perceived as a distinct group. For example, animals in a fenced-in enclosure are more likely to be seen as a group than are the same distribution of animals arrayed in open space. Also called law of common region; principle of common region. [proposed in 1992 by U.S. psychologist Stephen E. Palmer (1948– )]