Artificial Life VI


Evolved Signals: Expensive Hype vs. Conspiratorial Whispers

Jason Noble
School of Cognitive and Computing Sciences, University of Sussex
http://www.cogs.susx.ac.uk/users/jasonn/


Abstract

Artificial life models of the evolution of communication have usually assumed either cooperative or competitive contexts. This paper presents a general model that covers signalling with and without conflicts of interest between signallers and receivers. Krebs and Dawkins (1984) argued that a conflict of interests will lead to an evolutionary arms race between manipulative signallers and sceptical receivers, resulting in ever more costly signals; whereas common interests will lead to cheap signals or "conspiratorial whispers". Simple game-theoretic and evolutionary simulation models suggest that signalling will evolve only if it is in the interests of both parties. In a model where signallers may inform receivers as to the value of a binary random variable, if signalling is favoured at all, then signallers will always use the cheapest and the second-cheapest signal available. Costly signalling arms races do not get started. A more complex evolutionary simulation was constructed, featuring continuously variable signal strengths and reception thresholds. As the congruence of interests between the parties became more clear-cut, the evolution of successively cheaper signals was observed. The findings are taken to support a modified version of Krebs and Dawkins's argument.


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