An ERP investigation of individual differences in the processing of wh-dependencies by native and non-native speakers

Abstract

This study examines the processing of wh-dependencies by native English speakers and Mandarin Chinese-speaking learners of English. Wh-dependencies involve a long-distance relationship between a fronted wh-word (e.g., who) and the position in the sentence where it originated, called a gap site. The examination of wh-dependency resolution presents an interesting test case for whether or not grammatical knowledge is used online because, in languages such as English, wh-movement is constrained such that extraction is only possible from certain positions and is barred from other positions, called islands (Ross, 1967). In examining whether native speakers and second language (L2) learners are sensitive to island constraints online, this study tests predictions of prominent L2 processing theories which argue that adult learners are unable to utilize abstract grammatical information during processing (e.g., Clahsen & Felser, 2006). In the native literature, the processing of wh-dependencies has been proposed to involve at least two distinct processes, a predictive process in which the parser searches for a potential gap site, and an integrative process, when the dependency is successfully resolved at the gap site. The broader electrophysiological literature has linked these qualitatively different processes to distinct event-related potential (ERP) components: the N400 for prediction (e.g., Federmeier, 2007; Lau et al., 2008; 2013; Michel, 2014; Van Berkum et al., 2005), and the P600 for syntactic integration (e.g., Gouvea et al., 2010; Kaan et al., 2000; Phillips et al., 2005). Although previous ERP studies have examined these components independently, few studies have tracked the dynamics of wh-dependency resolution across the sentence, examining both prediction and integration to investigate whether these processes are indexed by unique components. The present study takes this approach, focusing on the processing of wh-dependencies at three critical regions across the sentence, two of which are associated with prediction, and one with integration. This study additionally investigates the extent to which the use of grammatical knowledge during online processing and the ability to engage in predictive processing is modulated by proficiency in L2 learners, and performance on a range of cognitive measures in native speakers. Results show that both native speakers and highly proficient learners engage in gap prediction during processing, although this is limited to certain contexts for learners. In examining processing inside of an island, a position from which extraction is prohibited, the current study shows that native speakers and highly proficient learners are guided by grammatical knowledge. Finally, both natives and learners show evidence of successful dependency resolution at the actual gap site, even in sentences with islands. Overall, the results present a complex picture of processing wh-dependencies by native English speakers and Mandarin-speaking learners of English, showing that while both native speakers and learners with higher proficiency are able to use grammatical information during online processing, the contexts in which L2 learners are able to predict differ from native speakers.