Déformation professionnelle is a French phrase, meaning a tendency to look at things from the point of view of one's own profession rather than from a broader perspective. It is often translated as "professional deformation" or "job conditioning," though French déformation can also be translated as "distortion." The implication is that professional training, and its related socialization, often result in a distortion of the way one views the world.
As a term in psychology, it was likely coined by the Belgian sociologist Daniel Warnotte or Russian-American sociologist Pitirim Sorokin.
Alexis Carrel: "Chaque savant, grâce à une déformation professionnelle bien connue, s'imagine connaître l'être humain, tandis qu'il n'en saisit qu'une partie minuscule." / "Every specialist, owing to a well-known professional bias, believes that he understands the entire human being, while in reality he only grasps a tiny part of him." L'Homme, cet inconnu, Chapter 2, p. 43, Harper & Brothers, 1935. [2]