INVESTIGATION OF BILINGUAL LANGUAGE PROCESSING VIA PUPILLOMETRY.

Abstract

This study used pupillometry to examine how language similarity and cognate status affect bilingual word recognition and cognitive effort. Two bilingual groups—English–French (EF) and English–Mandarin (EM)—completed language identification and lexical decision tasks under three conditions: No Control, Control (including non-words), and Cognate. Pupil dilation, reaction time, and accuracy were recorded throughout. Results showed that the No Control condition produced the fastest and most accurate responses, while the Control condition caused slower responses and lower accuracy due to the added demands of non-word processing. The Cognate condition produced intermediate performance, reflecting additional cross-linguistic processing demands. EF bilinguals demonstrated stronger cognate effects and greater cognitive effort than EM bilinguals, suggesting that language similarity increases cross-linguistic activation. Pupillometry findings aligned with behavioural data: higher-demand conditions produced larger pupil dilations, indicating greater mental effort. EF bilinguals showed increased pupil dilation for cognates, suggesting that cognates can create lexical competition rather than facilitation, whereas EM bilinguals showed little cognate-related effect. Overall, the findings demonstrate that bilingual lexical processing is influenced by both task demands and language relatedness, support refinements to the BIA+ model, and highlight pupillometry as a sensitive tool for studying cognitive mechanisms in bilingual word recognition.