Signaling Games

Signaling games are strategic interactions in which one party (the sender) has private information and another (the receiver) must act on the basis of a signal the sender chooses to transmit. Introduced by economist Michael Spence to model job-market signaling, the framework has become central to evolutionary biology, linguistics, and the study of animal communication.

The evolutionary analysis of signaling games, developed by Maynard Smith and extended by Amotz Zahavi, produces a counterintuitive result: honest signals are stable only when they are costly enough to be prohibitive for dishonest senders. The handicap principle — that a peacock's tail or a stag's roar is honest precisely because it is expensive — is an application of evolutionarily stable strategy analysis to communication. Cheap talk, in contrast, can be invaded by lying and is evolutionarily unstable unless the interests of sender and receiver are perfectly aligned.

The framework extends to human institutions: warranties signal product quality, educational credentials signal worker productivity, and charitable donations signal wealth. In each case, the signal's value depends on its cost differential between high-quality and low-quality senders. The formal logic of signaling games thus underwrites a surprising range of social and biological phenomena through the single principle that information is credible only when dishonesty is expensive.