One of the fundamental questions in the field of language acquisition is a learnability problem, which considers how learners acquire certain aspects of language which are not directly provided in the input or whose referents are not readily observable. This dissertation investigates Japanese children's acquisition of various linguistic phenomena,…

The present dissertation reports two experiments that examine implicit and explicit language learning methods and their impacts on early vocabulary, grammar, and phonological acquisition, in addition to working memory, proactive/reactive control, and fluid intelligence, as well as learner motivation. Experiment 1 investigated adult L2 acquisition…

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,"…

Gestures and other bodily movements are frequently used as instructional strategies in second language classrooms. Research has demonstrated that gestures are an effective strategy to improve L2 vocabulary recall. However, previous studies have only used vocabulary items that are known to participants in their native languages. Additionally,…

The importance of input on language learning cannot be overstated. One method of providing input to learners at a level that is appropriate for them is called extensive reading, in which learners read an abundance of texts. In practice, for learners of English as a second or foreign language, these texts are often books that have been written and…

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…

The question of whether second languages (L2s) are best learned implicitly or explicitly has been a topic of much empirical discourse, with the majority of studies pointing to the benefits of explicit instruction when learning L2 grammar rules. However, given the focus on grammar, it is unclear how generalizable these findings are to other…

The acquisition of a sound system is an integral component of second language (L2) communication, yet it is one of the most difficult skills to teach and is therefore largely ignored in L2 classrooms (Derwing, 2010). In laboratory settings, phonetic training studies have typically examined syllables, rather than words, with no referential meaning.…

This dissertation presents various machine learning applications for predicting different cognitive states of students while they are using a vocabulary tutoring system, DSCoVAR. We conduct four studies, each of which includes a comprehensive analysis of behavioral and linguistic data and provides data-driven evidence for designing personalized…

Lexical categories like noun and verb are foundational to language acquisition, but these categories do not come neatly packaged for the infant language learner. Some have proposed that infants can begin to solve this problem by tracking the frequent nonadjacent word (or morpheme) contexts of these categories. However, nonadjacent relationships…

This dissertation tests a new account of rapid word learning and vocabulary growth that these processes develop as the result of attentional biases to the features of a category that are relevant to labeling/categorization, built as the result of word-learning experience within each category. Study 1 demonstrated that children's vocabulary size…

This study sought to validate adult-child shared storybook reading as a method for teaching target vocabulary words to preschool children with disabilities. The Vocabulary Learning through Books (VLTB) instructional procedure incorporates, adult-child book reading, questioning during reading requiring the child to answer with a target word, and…