Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We develop a method for random assignment of language to participants in a controlled laboratory experiment, and use this to test the learning efficiency hypothesis (LEH henceforth), that languages are learned more quickly when they can be determined with fewer number of observations according to theory. This hypothesis plays a crucial role in the development of the theory of learning efficiency of compositional languages. Despite this, evidence on the empirical validity of the LEH has been elusive. Here we develop a novel extension of a coordination game within which languages emerge endogenously. We show that one can control features of an emergent language by varying the game's incentives. This enables us to compare speed of learning across participants randomly assigned to different languages. Our data provide cogent evidence supporting the LEH: languages with structures that theory implies can be determined with fewer observations are learned more quickly in the lab, and are in this sense more efficient.