Endogenous or exogenous? The data don't say
In an exciting in depth study of Korean language learners, Han, Musolino, and Lidz (1) show that children often arrive at grammars that do not match their parents. Learners appear to choose between multiple linguistic systems that are consistent with their most direct observed evidence. The authors frame these results as informing the nature vs. nurture debate: because learners acquire a grammar that is not determined by their input, they must be bringing information to the problem "on the basis of an internally driven learning mechanism" (1)
Proceedings of the National Academy of Sciences