This dissertation investigates when and how children figure out the force of modals, that is, when and how they learn that "can/might" express possibility, whereas must/have to express necessity. Learning modal force raises a logical "Subset Problem": given that necessity entails possibility, what prevents learners from…

Infants and toddlers experience the world in interaction with others. Likewise, social interactions are important in learning about math--concepts of number ("one," "two," "three"), space ("on top," "upside-down," "round"), and magnitude ("more," "big,"…

When learning a language, typically-developing infants face the daunting task of learning both the sounds and the meanings of words. In this dissertation, we focus on a source of variability that complicates the one-to-one relationship between words and their meanings: wordform variability. In Chapter 1 we make a distinction between the micro…