The arena of language evolution: the emergence of symbolic referential signals in a common task framework

We present the common task framework approach to testing causal theories about the evolution of language. There are now many theories about how symbolic communication emerged, but less work trying to compare, synthesize and test these theories. We suggest that the first step is to formalize the theories as causal graphs using tools from the field of causal inference. This helps recognize the critical causal links that differentiate theories. The second step is to use methods from lab-based experimental semiotics to specify a ‘common task’ or ‘arena’: an experimental environment and a task for individuals to complete. The different theories suggest different designs for this arena, and the experimental results can be used as a measure of the relative success of each theory. In this paper, we provide an example from anthropological theories of the emergence of symbolic communication, suggesting that an effective arena contains an asymmetry of information, division of labour and contextually distal meanings. We run experiments in arenas based on collaborative construction and fire maintenance. The results indicate that the effectiveness of pointing can limit the emergence of symbolic signals, a problem that has previously not been worked into theories. In this way, we hope the common task framework can be used as a method to further develop theories of language evolution.