Pupillary responses reveal cognitive effort during second language word recognition in adolescent learners

Abstract It is widely established that processing language imposes considerable demands on cognitive resources, particularly in bilinguals who must simultaneously coordinate more than one language. While previous research has addressed top-down language control mechanisms during bilingual language processing, comparatively fewer studies have directly studied the cognitive effort involved in bottom-up lexical access during bilingual word recognition. Thus, this study focusses on factors assumed to modulate cognitive demands during bilingual word recognition, namely cognate status and lexical frequency. Besides decision accuracies and RTs, we measured changes in pupil size during visual word recognition in adolescent German learners of L2 English. Participants performed a visual lexical decision task in English, with German-English cognates and noncognates varying in lexical frequency. We found main effects of cognate status and frequency, with cognates and higher-frequent items being responded to more accurately and faster. Analyses of pupillary responses over time revealed an interaction of both factors, with a cognate advantage mainly present in lower-frequent items. Exploratory analyses of the pupillary data further suggested that cognate effects varied depending on lexical form similarity. Together, these findings indicate that cognate facilitation is particularly evident under increased processing demands and varies in strength and temporal dynamics across cognate types.