Conspiratorial whispers and conspicuous displays: Games of signal detection

Recent models of signaling have assumed that the expenditure required to en sure detection of a display is negligible and have concentrated instead on the costs that may be necessary to maintain honesty. Such models predict th at individuals who share the same interests are likely to communicate using "conspiratorial whispers," signals that are cheap and inconspicuous. Here, I present a game-theoretical model of signal detection (in a noisy environ ment, in the presence of potential eavesdroppers), which demonstrates that the idea of conspiratorial whispers is far too simplistic. It is true that in "cooperative" signaling systems (where signalers attempt to elicit respo nses that are beneficial for receivers), signal cost is not required to mai ntain honesty. However, some level of expenditure is still needed to ensure that a signal is reliably detected. Moreover, there exists a conflict of i nterest between signalers and receivers over the division of this expenditu re. To predict the stable level of display in such cases, one needs to know how this conflict of interest will be resolved. The model reveals that the outcome may range from a whisper to a conspicuous and costly (though still conspiratorial) display. The more closely related the receiver is to the s ignaler, the greater the level of signal exaggeration that is expected-the opposite prediction to that of honest signaling models.