Native word order processing is not uniform: An ERP study of verb-second word order

Studies of native syntactic processing often target phrase structure violations that do not occur in natural production. In contrast, this study examines how variation in basic word order is processed, looking specifically at structures traditionally labelled as violations but that do occur naturally. We examined Swedish verb-second (V2) and verb-third (V3) word order-processing in adult native Swedish speakers, manipulating sentence-initial adverbials (temporal idag ‘today’, spatial hemma ‘at home’, and sentential kanske ‘maybe’) in a written sentence completion task, in acceptability judgements, and neurocognitively as event-related potentials (ERP) recorded to visually presented sentences. An initial corpus study showed that the adverbials differ in frequency in fronted position (idag > kanske > hemma), and although all occur mainly with V2 word order, kanske occurs more frequently with V3 in natural production than both idag and hemma. The experimental results reflected these patterns such that V2 sentences were overall more frequently produced and were deemed more acceptable than V3 sentences. The ERP results revealed no indication of sentence reanalysis on the P600 amplitude with V3 word order, but rather an expected increase of the amplitude of the N400 effect. We found consistent effects of adverbials. As predicted, V3 kanske-sentences were produced more frequently and were judged as more acceptable than sentences with the other adverbials. The ERP analyses showed an unexpected prolonged and more widely distributed negativity (300-1000 ms) with kanske in comparison to with idag and hemma (restricted to 300-700 ms) possibly indicating that the processing of the naturally occurring V3 with kanske is more effortful than processing of V3 with other adverbials. Taken together the results suggest a more varied native word order processing than previously reported.