eg, birds warning each other that there is a snake in the grass
Wait, this is not the example in the Wikipedia page, which is actually “When an alert bird deliberately gives a warning call to a stalking predator and the predator gives up the hunt, the sound is a signal.”
I found this page which gives a good definition of signaling:
Signalling theory (ST) tackles a fundamental problem of communication: how can an agent, the receiver, establish whether another agent, the signaller, is telling or otherwise conveying the truth about a state of affairs or event which the signaller might have an interest to misrepresent? And, conversely, how can the signaller persuade the receiver that he is telling the truth, whether he is telling it or not? This two-pronged question potentially arises every time the interests between signallers and receivers diverge or collide and there is asymmetric information, namely the signaller is in a better position to know the truth than the receiver is. ST, which is only a little more than 30 years old, has now become a branch of game theory. In economics it was introduced by Michael Spence in 1973. In biology it took off not so much when Amotz Zahavi first introduced the idea in 1975, but since, in 1990, Alan Grafen proved formally that ‘honest’ signals can be an evolutionarily stable strategy.
Typical situations that signalling theory covers have two key features:
there is some action the receiver can do which benefits a signaller, whether or not he has the quality k, for instance marry him, but
this action benefits the receiver if and only if the signaller truly has k, and otherwise hurts her — for instance, marry an unfaithful man.
So in the alarm example, the quality k is whether the bird has really detected the predator, and the “action” is for the predator to give up the hunt. Later in the Wikipedia article, it says “For example, if foraging birds are safer when they give a warning call, cheats could give false alarms at random, just in case a predator is nearby.”
Indeed, to me ‘signalling’ is doing some action which is differentially costly depending on whether some fact is or isn’t true—so mere assertion doesn’t count, even if it conveys information.
Wait, this is not the example in the Wikipedia page, which is actually “When an alert bird deliberately gives a warning call to a stalking predator and the predator gives up the hunt, the sound is a signal.”
I found this page which gives a good definition of signaling:
So in the alarm example, the quality k is whether the bird has really detected the predator, and the “action” is for the predator to give up the hunt. Later in the Wikipedia article, it says “For example, if foraging birds are safer when they give a warning call, cheats could give false alarms at random, just in case a predator is nearby.”
Indeed, to me ‘signalling’ is doing some action which is differentially costly depending on whether some fact is or isn’t true—so mere assertion doesn’t count, even if it conveys information.