Introduction
In less than a year, children go from a vocabulary of one or two words to a productive corpus of 300+ items, with some estimates indicating that children are learning nine new words a day. Unfortunately, the mechanisms whereby such a shift occurs are not yet well understood. Explanations range from social-pragmatic accounts that highlight the role of the parent-child interaction, to constraints or principles accounts that stress the importance of cognitive heuristics in language acquisition, to associationistic theories that emphasize domain-general learning mechanisms of attention. In addition, there are also interactionist models that attempt to combine aspects of all of these positions.