An event-related FMRI study on case and number agreement processing in native and proficient nonnative speakers of Basque
Differences in native and nonnative sentence processing may surface most clearly around parameters that are not shared between L1 and L2. We investigated whether differences between Spanish-Basque bilinguals exist in processing related to the particular constraints of the ergative-absolutive case system of Basque, which is not present in Spanish, but not in processing related to number agreement which occurs in both languages. In an event-related FMRI experiment, we tested this hypothesis by examining the cortical networks recruited for reading in Spanish-Basque bilinguals. Highly proficient nonnative and native speakers of Basque read sentences containing violations of ergative case assignment or violations of number agreement as well as correct sentences (e.g., “Gizonak lehiatilan jaso ditu sarrerek/sarrera/sarrerak goizean”, respectively, approximate translation: “The man at the box office has received the tickets-erg/ticket/tickets in the morning”) while performing an acceptability judgment task. Preliminary results (6 nonnative and 16 native speakers) showed that ergative case violations and number violations similarly elicited activation increases compared to correct sentences in the right inferior parietal lobule and the precuneus while number violations elicited additional activation increases in middle and inferior frontal cortex, consistent with reports for morphosyntactic agreement errors. Compared to native speakers, nonnative speakers engaged the medial prefrontal cortex more strongly while processing ergative case violations and number violations, suggesting that they engaged additional cognitive resources to arrive at the same behavioral outcome. These latter effects, however, did not seem to differ between the ergative case and number violations. Thus, our preliminary results support the hypothesis that while morphosyntactic processing is quantitatively different in the two groups, native and nonnative speakers do not show qualitatively different responses when processing morphosyntactic features that are specific of the L2.