Costly Signalling

A costly, observable action that reveals private information because faking it would not pay.

This explains warranties, credentials, notice periods and probation better than trust does. None of them are about honesty; each is a cost structured so that only somebody telling the truth can comfortably bear it. It also accounts for a great deal of otherwise baffling behaviour — conspicuous expenditure, qualifications for jobs that do not require them, and making people prove commitment through inconvenience. The mirror-image result matters too: cheap talk conveys information only when interests are already aligned, which is exactly when you needed it least.

How it feels

• Somebody is spending real resources purely to be believed.
• The expensive thing has no direct use — its only job is to be expensive.
• Two parties are saying identical words and only one is staking anything.
• A requirement exists that does not obviously improve the work.

Who is playing

The sender, the receiver, and the pool of other senders the receiver is comparing against. A signal only separates relative to a population, so the other candidates are players even though they never appear.

Where it lands

If costs differ enough by type, the types separate and the signal is informative. If not, everyone sends it, it costs everybody, and it tells nobody anything — an arms race in credentials.

What moves it

Design the screen rather than judging the person: deposits, staged payments, trial periods, references that cost something to obtain. And watch for signal inflation — when everyone can afford the signal it stops separating and becomes pure waste.

Not to be confused with

Nearly every misread in practice is a shape mistaken for its neighbour — and each of those mistakes points you at the wrong fix.

Where you have already met it