Before revision:  In our model, young senders are uncertain about the prevailing distribution of play, so they rationally send out-of-equilibrium signals as experiments to learn about receivers' behavior . Differences in the payoff functions of the types of senders generate different incentives for these experiments.
After revision:  In our model, young senders are uncertain about the prevailing distribution of play, so they rationally send out-of-equilibrium signals as experiments to learn about the behavior of the population of receivers . Differences in the payoff functions of the types of senders generate different incentives for these experiments.