Yerkes-Dodson law
Also known as: Arousal-performance relationship, Inverted-U hypothesis
Performance rises with arousal up to a point, then falls — and the optimum is lower for hard tasks.
What it means
The Yerkes-Dodson law describes an inverted-U relationship between physiological or mental arousal and performance: too little arousal leaves performance sluggish, moderate arousal optimizes it, and excessive arousal degrades it. A second component holds that the optimal level of arousal depends on task difficulty — simple, well-learned tasks tolerate and even benefit from high arousal, while complex or novel tasks are best performed at relatively low arousal. The mechanism is often explained through attention: moderate arousal sharpens focus, whereas high arousal narrows it excessively and disrupts the working memory that hard tasks demand. The nuance is that the 'law' is an empirical generalization with many exceptions and an oversimplified single curve; arousal is multidimensional. It matters across performance domains — sports, exams, public speaking — as a rationale for managing pressure to a task-appropriate level.
Examples
Mild nerves sharpen a sprinter, but the same intense arousal that powers the race would wreck a chess player solving a delicate endgame.
The deadline that sharpens a designer on Tuesday becomes panic on Friday night, when the same pressure has her rewriting a brief she had already solved.
Nerves add snap to a wedding toast you have rehearsed a hundred times, but wreck a job interview, where every answer has to be built on the spot.
First described in Robert Yerkes & John Dodson (1908).