Werker, J. .
The process of language acquisition begins in perceptual development long before infants produce or even understand, their first words. In this talk, I will review the rapid changes in auditory, visual, and multimodal speech perception that occur in the first months of life as a function of growing up with one or more languages, and how growing perceptual knowledge of the native language(s) intersects with higher levels of language acquisition. I will then present evidence that, while under typical circumstances the timing of perceptual attunement seems to be constrained by maturation, there are identifiable variations in experiences that can accelerate, slow down, or modify this developmental trajectory. Finally, I will introduce new questions about whether or not studies to date on the timing of plasticity have considered all the relevant input systems. The implications of these findings for better understanding language development in both typically developing and atypical populations will be considered.