Is It Time to Reconsider the 'Gold Standard' for Nativelikeness in ERP Studies on Grammatical Processing in a Second Language? A Critical Assessment Based on Qualitative Individual Differences

In most event-related potential (ERP) studies on the second language (L2) processing, the native speaker (L1) control group's grand average ERP pattern serves as the 'gold standard' that the L2 group has to reach to be labeled 'native-like'. This relies on the assumption that the grand average is representative of all or most individuals in a group. Recent research, however, has shown that there can be considerable systematic qualitative variability between individuals even in coherent L1 samples, especially in studies on morphosyntactic processing. We discuss how these qualitative individual differences can undermine previous findings from the gold standard paradigm, and critically assess the main ERP components used as markers for nativelike grammatical processing, namely the left-anterior negativity and the P600. We argue that qualitative variation reflects the dynamics characteristic of nativelike grammatical processing and propose a model for experimental designs that can capture these processing dynamics and, thereby, has the potential to provide a more fine-grained understanding of nativelike attainment in an L2.