Yerkes-Dodson Law
A principle in psychology holding that performance improves with rising arousal up to a point, after which further arousal causes performance to decline — forming an inverted-U curve whose peak shifts depending on task difficulty.
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Origin
Robert Yerkes and John Dodson published the original finding in 1908 in the Journal of Comparative Neurology and Psychology. Their experiment used Japanese dancing mice navigating a brightness-discrimination task under varying electric-shock intensities. They found that optimal stimulation decreased as task difficulty increased — a result later reinterpreted as the famous inverted-U relationship between arousal and performance.
Updated February 22, 2026