| This study examines several related issues concerning second language acquisition and processing: what computational and neural systems underlie second language acquisition and processing at both low and high proficiency levels; whether later learners can achieve native-like proficiency; and how conditions to which second language (L2) learners are exposed (e.g., explicit and implicit conditions) affect these issues. Informed by the fields of cognitive neuroscience and second language acquisition (SLA), this study investigated the neurocognitive underpinnings of adult acquisition and use of L2 by using an artificial language paradigm, following Friederici, Steinhauer and Pfeifer (2002). Adult subjects learned an artificial language to advanced levels of proficiency under two training conditions: explicit and implicit. Syntactic and morphosyntactic processing were assessed within-subjects and across training conditions with both behavioral and neurocognitive measures, specifically event-related potentials (ERPs), at low and high proficiency levels. Behavioral results indicated that participants from both groups performed similarly at low and higher levels proficiency, although the explicit training condition led to some advantage for one morphosyntactic form. These results are largely consistent with the findings of Sanz and Morgan-Short (2004). ERP results showed that the implicit condition led to an N400 component for syntactic and morphosyntactic structures at low proficiency and to a LAN-P600 biphasic response for these structures at higher levels of proficiency whereas the explicit condition did not lead to the predicted components. Interestingly, the biphasic response evidenced by the implicit group is consistent with the typical response evidenced in L1 to these structures. The neurocognitive processing underlying performance of the implicit group is consistent with the results from Friederici, Steinhauer and Pfeifer (2002) as well as with the predictions of the declarative/procedural model (2001a; 2001b; 2004; 2005). Overall, the explicit and implicit conditions did not differentially affect L2 knowledge as reflected by behavioral assessments but they did appear to affect the cognitive processing that underlies use of the L2 knowledge. Future research that fully considers and incorporates theory and research methodology from SLA and cognitive neuroscience is likely to provide insights into L2A and have significant implications for our understanding of L2A. |
