The emergence of word order and morphology in compositional languages via multigenerational signaling games

The experimental study of language change may provide novel insights into the nature of language, in particular on the role of cognitive biases and social processes in shaping grammatical and semantic structures. Here, we introduce multigenerational signaling games (MGSGs) as a new experimental paradigm for investigating how simple compositional languages emerge and change during transmission across generations in a diffusion chain, where each transmission step requires coordination between sender and receiver in a signaling game. We obtained three main results. First, we replicate and extend earlier findings by Moreno and Baggio suggesting that, in signaling games with fixed roles, mappings of signals to meanings tend to be transmitted from senders to receivers. We show that this holds for signaling games played in diffusion chains too, in which the receiver in one game becomes the sender in the next game. Second, we provide an experimental proof of concept that MGSGs are a viable laboratory model of cultural language change. Players consistently agreed upon a common signaling system after repeated signaling rounds, and the resulting code was effectively transmitted and gradually modified over generations. Third, we establish a baseline of results for further research using MGSGs. We found that the order of elements initially imposed on signals is largely maintained by successive generations. Moreover, the degree of coordination among players and the fidelity of inter-generational transmission exhibit a cumulative increase across generations. Finally, replicating a seminal result by Esper, we observed that morphological marking of semantic categories such as agent, action, and patient emerged gradually in the course of transmission.