ERP correlates of word order and morphosyntactic phenomena in adult native speakers and second language learnersof English

This study examined Event-Related Potential (ERP) responses to syntactic and inflectional violations in L2 learners of English (Spanish L1) who differ in proficiency and age of acquisition. L2 groups included high-proficiency early (HPE) learners, acquiring English before age 8, high-proficiency late (HPL) learners, acquiring English after age 8, and low-proficiency (LP) learners. A native English speaking control group was included. ERP responses were recorded over 64 channels while subjects listened to sentences and performed a grammaticality judgment task. Stimuli were present progressive sentences, which included violations of word order (NOT-IS) and verbal inflection (missing -ING).; For monolinguals, Word Order (WO) violations elicited an Early Left Anterior Negativity (ELAN) response, which is thought to reflect processes of first-pass structure building based upon word category information. Monolinguals showed a LAN response (250--450 ms), generally associated with morphosyntactic analysis. Negativities in both latency ranges were fronto-centrally distributed. HPE learners showed increased negativity at left fronto-temporal sites in the LAN latency range. HPE learners showed no increased negativity in either latency range to WO violations. Late centro-parietal positivity (P600) is associated with controlled processes of syntactic reanalysis, repair, and integration. P600 effects were observed in Monolinguals. In HPE and HPL groups this effect occurred later (between 700--800 ms). No P600 effect was seen in the LP group.; Inflection violations elicited a LAN followed by later, weaker P600 effects in monolinguals. HPE learners showed increased temporo-parietal negativity that did not reach significance at frontal sites. P600 effects occurred in half of the HPE learners and were absent in HPL and LP groups.; Similar accuracy rates in monolinguals and high-proficiency groups but slower reaction times for HPL learners were found. These results suggest differential processing for syntactic and inflectional violations in monolinguals. While ERP patterns show that processing in later L2 learners differs from native speakers, the underlying grammatical knowledge of word order and verb inflection is the same in both early and late high-proficiency learners and native speakers. These findings suggest maturation effects for processing syntactic and inflectional by age of acquisition.