Signal

A signal in economics, biology, and communication theory is any observable behavior or trait that conveys information about an unobservable property. The concept was formalized in economics by Michael Spence, who showed that in markets with asymmetric information, agents may engage in costly signaling to distinguish themselves from less desirable types. A university degree signals ability not because education is inherently valuable, but because obtaining it is costlier for low-ability individuals than for high-ability ones. The cost, not the content, does the communicative work.

Signals are ubiquitous but fragile. In network science, signals propagate through topology, amplified or attenuated by the structure of connections. In information warfare, signals are manufactured: front groups send false signals of grassroots support, and coordinated inauthentic behavior floods information environments with synthetic signals designed to drown out authentic ones. When signaling becomes cheap — when anyone can send any signal at negligible cost — the signal loses its information value and the market for attention collapses into noise.