Event-related brain indices of gap-filling processing in Kaqchikel

In many languages with flexible word order, transitive sentences in which the subject precedes the object have been reported to have a processing advantage during sentence comprehension compared with those in which the subject follows the object. This observation brings up the question of why this subject-before-object (SO) order should be preferred in sentence comprehension, together with the related empirical question of whether this preference is universal across all human languages. In the present ERP study, we address these two issues by examining the word order preference in Kaqchikel, a Mayan language spoken in Guatemala, in which the verb-object-subject (VOS) order is the syntactically basic word order. In the experiment, native speakers of Kaqchikel were auditorily presented four types of sentences (VOS, VSO, SVO, and OVS), followed by a picture that either matched or mismatched an event described in a preceding sentence, while their EEGs were recorded. The result of the ERP experiment showed that VSO elicited a larger positive component, called a P600 effect, in the comparison to the canonical word order, VOS in the third region (i.e., O of VSO versus S of VOS), in which the filler-gap dependency was supposed to be established in VSO sentences. Furthermore, SVO also exhibited a P600 effect compared to VOS in the third region, reflecting an increased syntactic processing cost. These results indicate that the syntactically basic word order, VOS, requires a lower amount of cognitive resources to process than other possible word orders in Kaqchikel. Based on these results, we argue that the SO preference in sentence comprehension reported in previous studies may not reflect a universal aspect of human languages; rather, processing preference may be language-specific to some extent, reflecting syntactic differences in individual languages.