A box with a lever taught psychology that behavior is shaped by its consequences

B.F. Skinner built a chamber where an animal's own actions -- pressing a lever, pecking a disk -- triggered food, and recorded exactly how reward schedules changed behavior. The 'Skinner box' turned operant conditioning into something measurable, and it still underlies how casinos, apps and classrooms dole out reinforcement.

— B.F. Skinner, The Behavior of Organisms — Appleton-Century, 1938
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