Loss Aversion
The behavioral-economics finding that losses are felt more strongly than equivalent gains, formalized in prospect theory.
Loss aversion is the tendency for losses to be felt more strongly than equivalent gains: losing $100 typically hurts about twice as much as winning $100 pleases. Kahneman and Tversky's prospect theory (1979) formalized the effect with a loss-aversion coefficient λ of roughly 2, and it earned Kahneman the 2002 Nobel Memorial Prize in Economic Sciences.
Prospect theory replaces the symmetric utility curve of standard expected-utility theory with a value function that is concave for gains, convex for losses, and steeper for losses than gains. This single asymmetry explains several anomalies that standard supply-and-demand reasoning cannot: the endowment effect (people demand more to give up an object than to pay to acquire it), status quo bias, and the disposition effect (investors sell winners too early and hold losers too long).
The effect is robust and replicable in laboratory experiments, though its size varies across contexts, stakes, and cultures. It is routinely invoked to explain real-world behavior: why people overpay for extended warranties, why tax rebates are more effective than equivalent tax cuts, and why framing messages in terms of what will be lost changes behavior in health and savings campaigns.
Critics note that field evidence is mixed, that framing effects shrink in high-stakes or repeated decisions, and that expertise reduces the effect. Like other cognitive biases, loss aversion describes systematic tendencies — real, measurable, but not universal laws of behavior.
Tags
behavioral economics decision making prospect theory psychology