The Theory of Honest Signalling

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Introduction: Part 1

Introduction: Part 2

The Basic Problem

The Basic Solution

Honest signalling in biology

Zahavi's handicap principle

Grafen's model

Attracting mates

Begging for food

Deterring predation

Contesting resources

Autumn color

Honest signalling in economics

Conspicuous consumption


The mathematics of honest signalling

Signalling as a game


Other resources

Carl T. Bergstrom

Using Mathematica

Contact Information

Department of Zoology
University of Washington
Box 351800
Seattle, WA 98195-1800

The Basic Solution: Costly Signals

How can honest communication be ensured despite conflicting interests between a signaller and a signal receiver?

In both biology and economics, a number of authors recognized that there may be a connection between the cost of signals and the reliability or honesty of signals. This lead to a suggestion for a possible solution to the problem of honest communication despite conflicting interests. Loosely paraphrased, the solution typically took something of the following form.

Suppose that signals are costly, and that for one reason or another, lies cost more than honest signals.

If the extra cost of lying is sufficiently large, then it may never be worthwhile to lie.

Assuming that there is something to be gained from sharing information, communication still take place, and necessarily will be reliable despite the conflict of interest.

Of course, this solution left open many questions. What sort of mechanisms, biological or economic, would make lies cost more than honest signals? Do all signals have to be costly, or can honest signals be free? How much must lies cost in order for signalling to remain honest? Will individuals that use costly signals necessarily be better off than agents that simply decide not to communiate?

In the sections that follow, we explore these and other questions. We will begin by looking at costly signals in biology. Later, we will consider examples from economics.

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Last modified September 4, 2002
Copyright © 2002 Carl T. Bergstrom