Title: "Rules and variation in child language acquisition"
Abstract: One of the most well-known phenomena in language acquisition is that children can acquire rules when they are available (Berko 1955; Brown 1973). But precisely how children acquire such rules under circumstances of language variation is not as frequently discussed. In one literature, it is widely known that children exposed to stable language variation (e.g. Labov, 1989) can learn and match this variation in their own productions (Labov & Roberts, 1995; Roberts, 1997). However, evidence from a related literature suggests that children exposed to variation that is inconsistent – for example, from late learners or pidgin or creole speakers - do not learn and match the probabilities of the input variation, instead regularizing the dominant form in their productions (Singleton & Newport 2004, Hudson-Kam & Newport, 2005, 2009). In my work, I ask how we reconcile these two related but seemingly conflicting findings. What are the principles that govern when children learn rules and when they reproduce variation or inconsistency? In a series of experiments, I explore how the structure of the input, the maturational state of the child, and the social context of the learning could constrain the acquisition of variation. I further propose that particular constraints on the acquisition of categorical rules are well captured by a recent computational model of rule learning and generalization (Yang, 2016), suggesting a possible mechanism for this process.