In an eyetracking during reading study, Bott and Gattnar (2015) followed up on the observed cross-linguistic variation in the processing of grammatical aspect comparing an aspect language, Russian, with the non-aspect language German. They investigated whether the differences in the aspectual systems of the two languages affected the time course of mismatch detection in the case of lexical aspectual mismatch.All test sentences contained clear instances of (in Russian always perfective) transitive achievement verbs such as  win, find, reach, notice, etc. which were modified by a semantically mismatching for-adverbial (e.g., for three hours) or a semantically fitting ago-adverbial (e.g., three hours ago) in aspectual control conditions. Crucially, both Russian and German have relatively free word order making it possible to test for effects of mismatching vs. matchingadverbials in the word order  subject verb object adverbial but also in the order adverbial verb subject object. The results show that Russian readers immediately detect the aspectual  mismatch irrespective of whether they have seen the subject or the object argument yet. This is different in German where aspectual mismatch detection only started after the verb plus all its obligary arguments had been encountered. This result was modeled by Bott and Sternefeld (2017) in an incremental event semantics drawing on insights from mereological semantics as proposed by Krifka (1989, 1992); see  also  section 6.1 (and the entry  mereology). The incremental semantic derivations show that in a non-aspect language like German, lexical aspect really is a property of whole sentences and strongly depends on the compositional interpretation of the verb, its arguments, and their thematic roles. In an aspect language like Russian, on the other hand, the grammatical aspect imposes itself strong constraints on lexical aspectual interpretation. These psycholinguistic results thus nicely fit semantic proposals for grammatical aspect that have been proposed in the framework of mereological semantics (see, e.g., Filip 2008, a.o.).