Natural language is known to play a crucial and specific role for children's learning in school mathematics. Not only does it carry special vocabulary, but subtle differences between natural languages may lead to surprising challenges, for instance, for learners who are not taught mathematics in their mother tongue. In this paper, the…

This dissertation features a relative clause island, whose status has been known to differ significantly across languages and extraction types. By conducting a series of acceptability judgment experiments with human participants, as well as measuring token-by-token surprisal values among large language models, I demonstrate the following: First,…

Due to the typological differences between Korean's aspect system and English's aspect system in terms of progressive construction "-ko iss," learners can no doubt have difficulty acquiring and using the "-ko iss" construction in learner Korean. This dissertation investigates two main points: (i) how is the "-ko iss"…

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 current study examined the extent to which first language (L1) utterance fluency measures can predict second language (L2) fluency and how L2 proficiency moderates the relationship between L1 and L2 fluency. A total of 104 Japanese-speaking learners of English completed different argumentative speech tasks in their L1 and L2. Their speaking…

This dissertation developed a new learner corpus of Japanese and introduced an error and linguistic annotation scheme specifically designed for Japanese particles. The corpus contains texts written by learners who are in the first year to fourth year university level Japanese courses. The texts in the corpus were tagged with part-of-speech and…

Negation is a cornerstone of human language and one of the few universals found in all languages. Without negation, neither categorization nor efficient communication would be possible. Languages, however, differ remarkably in how they express negation. It is yet widely unknown how the way negation is marked influences the acquisition process of…

This study investigated the relative contributions of English morphological and vocabulary knowledge to second language (L2) reading comprehension among 100 adult Japanese English as a foreign language (EFL) learners. The study also investigated the extent to which the roles of morphological and vocabulary knowledge in L2 reading comprehension…

Research on second language (L2) pronoun use in null-argument languages has traditionally focused on whether or not a speaker's first language (L1) also allows null pronouns. However, recent studies have pointed out that it is equally important to consider the specific linguistic properties of overt pronouns in the L1 and L2, which may differ even…