Expectation and locality effects in German verb-final structures

Probabilistic expectations and memory limitations are central factors governing the real-time comprehension of natural language, but how the two factors interact remains poorly understood. One respect in which the two factors have come into theoretical conflict is the documentation of both locality effects, in which having more dependents preceding a governing verb increases processing difficulty at the verb, and anti-locality effects, in which having more preceding dependents facilitates processing at the verb. However, no controlled study has previously demonstrated both locality and anti-locality effects in the same type of dependency relation within the same language. Additionally, many previous demonstrations of anti-locality effects have been potentially confounded with lexical identity, plausibility, and sentence position. Here, we provide new evidence of both locality and anti-locality effects in the same type of dependency relation in a single language—verb-final constructions in German—while controlling for lexical identity, plausibility, and sentence position. In main clauses, we find clear anti-locality effects, with the presence of a preceding dative argument facilitating processing at the final verb; in subject-extracted relative clauses with identical linear ordering of verbal dependents, we find both anti-locality and locality effects, with processing facilitated when the verb is preceded by a dative argument alone, but hindered when the verb is preceded by both the dative argument and an adjunct. These results indicate that both expectations and memory limitations need to be accounted for in any complete theory of online syntactic comprehension.

► We report two eye-tracking studies on expectations & locality in German verb processing.
► We eliminate confounds in expectation-based facilitation from preverbal dependents.
► We find new evidence of locality effects when memory load is high.
► These results constrain theories of expectations & memory in sentence comprehension.