Jean Marie Joseph Capgras (23 August 1873 – 27 January 1950) was a French psychiatrist who is best known for the Capgras delusion, a disorder he discovered. He received his medical degree in Toulouse, later working in several mental institutions in France, although these duties were interrupted by the Great War. In 1929-1936, he was associated with Hôpital Sainte-Anne where he remained until his retierment. With his mentor, Paul Sérieux (1864–1947), he contributed on psychiatric publications such as Les Folies raisonnantes (1909) ("The Reasoning of Follies)" ) and Les Psychoses à base d'interprétations délirantes (1902) (“Psychoses Based on Delusional Interpretations”). With Sérieux, he described a type of non-schizophrenic, paranoid psychosis referred to as Delerium of Interpretation with Serieux and Capgras . Capgras delusion was described in 1923 in a study published by Capgras and his intern Jean Reboul-Lachaux, titled L'illusion des "sosies" (the illusion of doubles ) dans un délire systématisé chronique. This disorder is defined as a delusion that a close relative or friend has been replaced by an impostor.