The Effect of Word Informativeness on Eye-Movement Reading Behavior: Cross-Linguistic Variability and Individual Differences

Research has consistently demonstrated that the importance or centrality of a linguistic unit to a larger unit’s meaning affects multiple aspects of reading behavior. However, there is an ongoing debate on how to quantify a unit’s degree of importance or centrality, which subsequently limits our understanding of the impact of this important source of information. Here we introduce a novel measure, which we term “informativeness”, to assess the significance of a word to the meaning of its containing sentence. Our measure is based on the comparison of vectorial representations of the full sentence with a revised sentence without the target word, resulting in an easily interpretable quantification. We then leverage large-scale datasets of first (L1) and second language (L2) eye-movement data (from the Multilingual Eye-tracking Corpus, MECO), to investigate how informativeness impacts different eye-movement measures, across languages and levels of reading skill. Our results reveal that informativeness influences multiple eye-movement measures, with particularly notable effects on total reading duration and rereading rate, but not earlier oculomotor measures. The effects of informativeness on eye movements generalize to both first and second language readers, and diverse writing systems, although some interactions between informativeness and language do exist. Notably, we identify interactions between informativeness and individuals’ reading skills, with more pronounced effects among poorer readers. Together, these findings provide a deeper understanding of the interplay among multiple cues that collectively shape reading behavior.