FIHELaD has advanced the state of the art in several key ways. Traditionally, research on heritage language acquisition has examined either the majority or the minority language in isolation, focusing on specific age groups of bilingual children. FIHELaD moved beyond this approach by testing how person-level factors influence both the majority and minority languages of a given language pair, in children aged 5-12, within a classroom learning context. For the first time, FIHELaD applied contrastive focus in a visual-world eye-tracking experiment to investigate the developmental trajectory of the same minority and majority language in contact situations, while accounting for their differing typological focus properties. Furthermore, FIHELaD explored the predictive factors shaping bilingual language outcomes by measuring not only psycholinguistic but also sociolinguistic person-level variables. Finally, FIHELaD triangulated findings by integrating multiple sources of behavioural data (offline measures, real-time gaze tracking, and pupillometry) combined with advanced statistical modelling. This approach shed light on apparent discrepancies between offline and online findings within the same population, task, and grammatical construction. The findings from FIHELaD have important implications for research, education, and policy. For researchers, the project’s novel methodology can inspire future studies on heritage speakers across different language pairs. For educators, the results can guide targeted instruction to strengthen heritage speakers’ communicative abilities in daily life. For policymakers, the insights can support more effective language choices in high-stakes contexts, such as asylum hot-spots, to facilitate communication between migrants and officials.
