German-speaking children use sentence-initial case marking for predictive language processing at age four.

Adults incrementally integrate multiple sources of information to predict the upcoming linguistic structure. Although we have substantial evidence that children can use lexicosemantic information triggered by the verb, we have limited information as to whether children can use morphosyntax to generate predictions during the course of processing. Previous studies show that four-year-old Turkish-speaking children can use case-marking cues predictively; however German-speaking children have been reported to fail until late in development. The present visual-world eye-tracking study provides the first evidence from four-year-old German-speaking children (mean age: 4;03) interpreting sentence initial case marking cues independent of the identity of the verb and the canonical word order to predict the thematic role of the upcoming argument. We presented children with a visual context with a stereotypical but ambiguous event, the thematic structure of which can be resolved only on the basis of the case marking cues on subject-initial and object-initial structures locating the verb sentence-finally. Children were able to use the accusative case on the non-canonical object-initial utterances to predict that the upcoming argument should have the agent role before this argument and the verb became available. This study shows that the previously reported discrepancy between these two case-marking languages (i.e., Turkish and German) is not due to the crosslinguistic differences but due to methodological differences employed across studies. These findings provide support for language acquisition theories assuming early abstractions and adult-like parsing mechanisms predictively integrating multiple sources of cues.