Languages differ in how they mark the dependencies between verbs and arguments, e.g., by case. An eye tracking and EEG picture description study examined the influence of case marking on the time course of sentence planning in Basque and Swiss German. While German assigns an unmarked (nominative) case to subjects, Basque specifically marks agent arguments through ergative case. Fixations to agents and event-related synchronization (ERS) in the theta and alpha frequency bands, as well as desynchronization (ERD) in the alpha and beta bands revealed multiple effects of case marking on the time course of early sentence planning. Speakers decided on case marking under planning early when preparing sentences with ergative-marked agents in Basque, whereas sentences with unmarked agents allowed delaying structural commitment across languages. These findings support hierarchically incremental accounts of sentence planning and highlight how cross-linguistic differences shape the neural dynamics underpinning language use.This work was funded by Swiss National Science Foundation Grant Nr. 100015_160011 (B.B. and M.M.), the NCCR Evolving Language, Swiss National Science Foundation Agreement Nr. #51NF40_180888 (B.B. and M. M.), and the PhD Program in Linguistics and the Graduate Research Campus of the University of Zurich (A.E.). DEB is supported by a grant from the Harvard Data Science Initiative and the Branco Weiss Foundation. I.B.-S. is supported by an Australian Research Council Future Fellowship (FT160100437). I.L. is supported by grants from the Spanish Ministry of Economy and Competitiveness (Grant No. FFI2015-64183-P) and the Basque Government (IT1169-19). The authors thank Anne-Lise Giraud for the suggestion to include beta-band analyses, Vitória Piai for advice on EEG data processing, Giuachin Kreiliger for statistical consultation, Andrina Balsofiore and Edurne Petrirena for help recording the lead-in fragments, Nathalie Rieser and Debora Beuret for help with data collection and processing, and the Phonogram Archives of the University of Zurich for technical support. The authors also thank two anonymous reviewers for their helpful comments on an earlier version of the manuscript
