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…

Foreign language aptitude is defined as one's potential to learn a second language. A language learner with higher aptitude is predicted to learn more, faster, and reach a higher level of proficiency. If this is the case, one way to validate the construct of aptitude and its measure is to conduct a validation study in which measures of aptitude is…

Energy Conservation Theory of Second Language Acquisition (ECT-L2A) (Han, Bao, & Wiita, 2017b), an interdisciplinary theory juxtaposing a physics perspective and an applied linguistics perspective, conceptualizes individuals' ultimate attainment as a function of dynamic transformation of endogenous and exogenous energies throughout the…