"Variability" and "fractality," two key concepts in Complex Dynamic Systems Theory (CDST)--the former concerning changes and variations, and the latter concerning recursiveness and self-similarities--may seem contradictory at first glance. This forum piece attempts to elucidate how the two seemingly contradictory properties can…

Positive psychology (PP) is currently employing its modern research toolkit to examine how individual differences of hedonic (i.e. pursuing pleasure, fun, and painlessness) versus eudaimonic (i.e. pursuing meaning, self-worth, and growth) well-being motives play out against emotional and learning challenges or outcomes in life. Similarly oriented,…

The present study aimed to validate a 70-item Korean bilingual version of the Vocabulary Size Test (VST) using Rasch modeling. The goal was to assess the applicability of this Korean version of the VST for Korean learners of English in an English as a foreign language (EFL) context by examining validity evidence based on Messick's framework.…

Grit is among the individual difference (ID) variables that have recently come to the attention of researchers investigating second language acquisition. While some empirical evidence has been accumulated, it is clearly scant and limited, also because of the fact that many studies have looked into domain-general grit rather than this attribute as…

Relatively few studies in the field of second language acquisition have undertaken to investigate the interrelationships of constellations of individual difference variables. This is certainly true of how complexes of ID factors impact motivation to learn an additional language. In order to address this gap, the paper reports a study that examined…

How could individual differences in processing non-speech acoustic signals influence their cue weighting strategies for L2 speech contrasts? The present study investigated this question by testing forty L1 Chinese-L2 English listeners with two tasks: one for testing the listeners' sensitivity to pitch and temporal information of non-speech…

The influence of individual difference variables on second language (L2) listening comprehension has been an area of research that has been gaining renewed attention in recent years. The current study investigated the effects of two cognitive variables, aptitude and metacognitive awareness, on 107 native-Korean, English as a foreign language…

In many contexts of multilingualism, language learners can initiate communication in the target language (TL), or a contact language (such as English). Patterns of use emerging from these choices affect TL development. They also vary between individuals. Willingness to communicate (WTC) needs to be investigated in ways that capture these…

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 book highlights the roles of several individual difference (ID) variables on the language learning process, exploring them from both the students' and the teachers' perspectives. It presents the results of a large-scale, mixed-methods investigation which was conducted with secondary school pupils and their teachers in Hungary. The…

Children who attend English immersion institutions present largely different attitudes toward learning English. The current study attempted to explain these differences by examining the variations of children's temperament (i.e., impulsiveness and anxiety). The study also investigated whether parent-child interactions as a means for English…

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…

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)…

The English language is a catalyst for economic growth, modernization, and globalization. In this milieu, English language competency--defined as the practical ability to use English effectively in diverse contexts, encompassing linguistic, cognitive, and intercultural skills--is recognized as an essential skill (Amor et al., 2023). Research on…

This chapter is dedicated to the presentation and discussion of the results of the empirical investigation undertaken for the purpose of the present book. It concentrates on the outcomes of the in-depth analysis of the patterns of WTC, motivation, boredom and language anxiety, the relationships of these variables as well as the influences shaping…