Widespread use of the Modern Language Aptitude Test (MLAT) in L2 studies of individual differences implicitly assumes that L2 aptitude is a distinct cognitive facet. There is considerable evidence for prediction from L1 abilities to L2 learning. In this longitudinal study, L1-MLAT-L2 relations were examined in 307 US secondary students based on…

This longitudinal study with time-serial data examines for the first time whether different types of intraindividual variation in second language (L2) performance and cognitive functioning are related, and how and when they influence L2 development longitudinally in older adulthood. We analyzed the L2 development of 26 German-speaking adults aged…

This longitudinal study investigated development of second language (L2) reading comprehension ability and predictive contributions of five L2 reading components (word recognition speed, listening comprehension, vocabulary breadth, grammar knowledge and first language [L1] reading comprehension) using latent growth curve modelling. The…

This study longitudinally examined the effects of cognitive and sociopsychological individual differences (aptitude, motivation, personality) and the quantity and quality of second language (L2) experience on L2 speech gains in naturalistic settings. We elicited L2 spontaneous speech from 50 Chinese learners of English at the beginning and the end…

Millions of public-school students in the United States are identified as English language learners (ELLs), whose academic success is tied to their second language (L2) English education. Previous research in adult populations indicates that L2 proficiency is related to the contextual variable of the prevalence of one's first language (L1) among…

Spanish-speaking students constitute the largest subgroup of emergent bilingual (EB) students in the United States. Using longitudinal data on a nationally representative sample of Spanish-English EBs, we explore profiles of English reading trajectories and how early individual differences (i.e., early Spanish reading and English oral proficiency)…

Despite the growing body of studies on collocation learning in SLA research, there are hardly any studies taking the perspective of the individual learner or studies that have examined the effect of individual differences. This study--a qualitative component of a mixed-methods longitudinal project--presents an in-depth exploration of the intro-…

This paper examines evidence for relationships among individual differences (IDs) in L1 achievement, L2 aptitude, and L2 achievement. It begins by providing an overview of my academic journey from L1 educator to L2 researcher and explains the development of the Linguistic Coding Differences Hypothesis (LCDH). Next, I review Peter Skehan's…

In this preregistered, longitudinal study of early code-switching, 34 US-born, Spanish-English bilingual children were recorded with a bilingual family member at 2;6 and 3;6, in Spanish-designated and English-designated interactions. Children's Spanish and English expressive vocabulary and their exposure to code-switching were measured through…

Recent longitudinal approaches to second language (L2) pronunciation development have prioritized developmental trajectories, highlighting individual variation in phonetic learning over time. Aligning with this research paradigm, the present study examined voice onset time (VOT) production in Spanish/b/and/p/ over two semesters of elementary…

Studies that have measured pragmatic fluency in the form of planning time and speech rate, as indicators of processing ability, have confirmed that learners' processing ability and pragmatic knowledge are independent from each other. The present study is a longitudinal, developmental investigation which investigates whether the study abroad stay…

This study examines the extent to which extra-linguistic factors such as language dominance, order of acquisition and language of instruction are deterministic for multilingual transfer selection and subsequent development. We test two groups of Catalan-Spanish bilinguals acquiring English as an L3 in a controlled setting. We first examine…

The present study examines both properties of the language and properties of the learner to better understand variability at the earliest stages of second language (L2) acquisition. We used event-related potentials, an oral production task, and a battery of individual differences measures to examine the processing of number and gender agreement in…

Narrative production draws upon linguistic, cognitive and pragmatic skills, and is subject to substantial individual differences. This study aimed to characterise the development of narrative production in late childhood and to assess whether children's cumulative experience of reading fiction is associated with individual differences in narrative…

A number of longitudinal studies of L2 production have reported frequency effects wherein learners' produce more frequent words as a function of time. The current study investigated the spoken output of English L2 learners over a four-month period of time using both native and non-native English speaker frequency norms for both word types and word…