Neural correlates of processing case in adults and children

Sentence-initial arguments with role-specific case markers (e.g., accusatives) have been reported to be processed slower than arguments with default case markers (e.g., nominatives), both in adults and children. However, the evidence for this comes from studies that conflate word order and case, comparing initial arguments with default case and fronted (scrambled) arguments with role-specific case. Here, we disentangle these effects by studying the parsing of Basque sentences, where both role-specific (ergative) and default (absolutive) case can occur sentence-initially in canonical word order. Two EEG experiments explore how adults and six-year-old children process ergative and absolutive markers in sentence-initial position. We find that the ergative case elicits a power synchronization in theta compared to the absolutive case in both adults and children, an effect we attribute to retrieving more specific relational information from memory. In contrast, processing ergative case markers leads to a beta power desynchronization in adults but a synchronization in children. This suggests that six-year-old children are still developing top-down processing mechanisms for the parsing and integration of case marking information.