With the increasing prevalence of autism diagnoses globally, the overall aim of this dissertation is to improve our understanding of the linguistic aptitude of autistic individuals. Given that the autism diagnosis is a spectrum, we rely on the Autism Quotient (AQ) test, which measures the quantity of autistic-like traits an individual possesses,…

Previous literature has shown that voicing contrast is a difficult feature for Chinese-English emergent bilingual learners of L3 Spanish (Bravo Diaz, 2020; Chen, 2007; Zhang, 2022). The production of voicing contrast in stops has been broadly investigated in second and third language studies (e.g., Zampini, 1998; Llama, 2010; Wrembel, 2014), but…

While language aptitude and motivation are considered to be important contributors to second language (L2) attainment, two major gaps in the past research have been (1) a lack of nonlinear models stemming from a naive and tacit assumption that learning outcomes are linearly related to their predictors, and (2) a lack of unified and integrative…

Although a number of studies have been conducted to explore how various individual difference (ID) factors such as aptitude, motivation, and anxiety contributing to L2 learners' speech performance over a period of time of L2 learning, only a few examined the effect of the three ID factors on learners' L2 speech performances based on classroom…

Despite the importance that learners must place on using prosody appropriately in EIL interaction, pragmatic functions of prosody have been largely disregarded in teaching materials and classroom instruction (Nikolic, 2018). Moreover, with a recent change in classroom paradigms instigated by the global development of educational technologies and…

Over the last two decades, there has been an increasing interest in third language (L3) phonology (Cabrelli Amaro, 2012; Cabrelli Amaro & Wrembel, 2016). However, research so far has been primarily directed at specific stages of learning and has independently explored either production (e.g., Llama, Cardoso, & Collins, 2010; Llama &…

Second language (L2) writing has been determined to be influenced by what is read, with language learners tending to borrow words and short phrases from input texts while writing (e.g., Wang & Wang, 2015). This phenomenon is referred to as lexical alignment. Only one empirical study has investigated the influence that the linguistic complexity…

Languages generally use musical pitch variation of the voice as part of their sound systems (Maddieson, 2011)--pitch variations that can be somewhat reminiscent of music. Music ability and/or training may influence language processing (e.g., Bidelman et al., 2011; Delogue et al., 2010). In particular, studies have concluded that there may be a…

As part of the Dynamic Model of Multilingualism (DMM), Herdina & Jessner (2002) cite multilinguals' increased metalinguistic awareness as one of the key factors that distinguish third language acquisition from second language acquisition. Many TLA studies have sought to show that this increased metalinguistic awareness and the beneficial…

Very high-level, functional ability in foreign languages is increasingly important in many walks of life. It is also very rare, and likely requires an early start and/or a special aptitude. This study investigated the extent to which aptitude for explicit learning, defined as "analytic ability" and aptitude for implicit learning, defined…

This dissertation aims to understand the maturational and non-maturational aspects of early bilingualism and language attrition in heritage speakers who have acquired their L1 incompletely in childhood. The study highlights the influential role of age and input dynamics in early L1 development, where the timing of reduction in L1 input and the…

The purpose of this dissertation was to examine the relationships between working memory (WM) and three commonly used learning strategies or conditions in the nature of proficiency among adult L2 Russian learners. Based on the aptitude-learning condition interaction framework articulated by Robinson (2002b), the study identifies two types of…

This inquiry analyzed the relationships between individual differences and gains made in oral proficiency of adult, second language learners of Spanish during one semester studying abroad. Oral proficiency was measured using a pre/post-SA Computerized Oral Proficiency Instrument (COPI, CAL, 2009). Gain scores were correlated with two cognitive…

Due to their unique profile as childhood bilinguals whose first language (L1) became weaker than their second language (L2), heritage speakers can shed light on three key issues in bilingualism--timing, input, and cross-linguistic interaction. The heritage speakers of focus in this dissertation are Korean second generation immigrants mainly…

This study examined the second language (L2) development of adult learners of Spanish at three levels of proficiency during and after a semester of instruction. A fundamental goal was to identify cognitive and psychosocial individual differences (IDs) that can explain between-learner variation over time in order to expand our understanding of the…