Iconicity and Structure in the Emergence of Combinatoriality
One design feature of human language is its combinatorial phonology, allowing it to form an unbounded set of meaningful utterances from a finite set of building blocks. Recent experiments suggest how this feature can evolve culturally when continuous signals are repeatedly transmitted between generations. Because the building blocks of a combinatorial system lack independent meaning, combinatorial structure appears to be in conflict with iconicity, another property salient in language evolution. To investigate the developmental trajectory of iconicity during the evolution of combinatoriality, we conducted an iterated learning experiment where participants learned auditory signals produced using a virtual slide whistle. We find that iconicity emerges rapidly but is gradually lost over generations as combinatorial structure continues to increase. This suggests that iconicity biases, whose presence was revealed in a signal guessing experiment, manifest in nuanced ways. We discuss implications of these findings for different ideas about how biases for iconicity and combinatoriality interact in language evolution.