Towards an integrative theory of language aptitude

This dissertation works towards an integrative theory of language aptitude, exploring how multiple learner characteristics jointly influence second language learning. Drawing on Snow’s theory of aptitude complexes, this research conceptualizes language aptitude as a system of interacting components from across cognitive, affective, and conative domains. The first part of this dissertation examines network analysis as a methodological tool. Chapter 2 shows that network analysis can reveal complex relationships in cross-sectional data, highlighting variable importance and interactions without predefined predictors and outcomes. Chapter 3 extends network analysis to time-series data from a 32-week Dutch course, demonstrating how learner states (e.g., anxiety, motivation, and engagement) evolve over time and interact differently within and between individuals.
The second part of this dissertation reports findings from a large, empirical study of learners of Dutch in the Netherlands. Chapter 4 identifies five interconnected domains of learner individual differences, including cognitive abilities, proficiency level and use, motivation and effort, self-beliefs and emotion, and pro-social behaviours. Learning gains were associated with lower external pressure and higher multilingualism, with proficiency and length of residence moderating other relationships. Chapter 5 identifies five learner profiles based on these domains, ranging from broadly positive to negative and mixed profiles, though these profiles did not significantly differ in learning outcomes. Overall, the dissertation highlights the value of examining multiple interacting factors in language learning and positions network analysis as a promising exploratory approach for developing a more comprehensive theory of language aptitude.