Overview -------- Supplementary materials for the paper: " Using verb morphology to predict subject number in L1 and L2 sentence processing: A visual-world eye-tracking experiment". This repository contains: - **Appendix S1** (picture complexity effects on eye movements). - The **data** and the **R code** of the analyses and graphs. - An English translation of the **debriefing interview questions**. - A spreadsheet providing an **item list**. - Supplementary **table S1**, providing the detailed outcomes of the three cluster-based permutation analyses. - 4 **videos** illustrating the different trial types of the eye-tracking experiment and an **explanatory file** regarding these videos. All **visual stimulus materials** are available on IRIS: https://doi.org/10.48316/9pmb-pf98. Abstract --------- We investigated whether adult German native speakers and Dutch-speaking second-language learners of German exploit German regular verb morphology for predictive sentence processing and whether such predictive processing is moderated by working memory capacity and awareness of the predictive cue. In a picture-matching task with visual-world eye-tracking, the participants (first-language group: *n* = 31; second-language group: *n* = 30) saw two pictures of action scenes, varying in the number of referents depicted (singular versus plural). Simultaneously, they heard sentences in German in which the verb suffix represented the first reliable cue for grammatical number of the upcoming subject noun phrase. Successful exploitation of this number cue was measured as anticipatory button-press reaction times and eye-movements toward the correct picture, before subject onset. We found significant prediction effects in both the first-language and the second-language group, with anticipatory processing being somewhat faster in the native speakers than in the learners. Faster reaction times on prediction trials were associated with higher working memory scores. Debriefing interviews revealed that all participants had become aware that they could use the verb form predictively, adding further evidence that prediction can be a conscious process.