Bidialectal and monodialectal differences in morphosyntactic processing of AAE and MAE: Evidence from ERPs and acceptability judgments.

Introduction: African American English (AAE) has never been examined through neurophysiological methods in investigations of dual-language variety processing. This study examines whether contrastive and non-contrastive morphosyntactic features in sentences with and without AAE constructions elicit differing neural and/or behavioral responses in bidialectal speakers of AAE and Mainstream American English (MAE), compared to monodialectal MAE speakers. We compared electroencephalographic (EEG) and behavioral (grammatical acceptability judgment) data to determine whether two dialects are processed similarly to distinct languages, as seen in studies of bilingual codeswitching where the P600 event related potential (ERP) has been elicited when processing a switch between language varieties.

Methods: Bidialectal AAE-MAE speakers (n = 15) and monodialectal MAE speakers (n = 12) listened to sentences in four conditions, while EEG was recorded to evaluate time-locked brain responses to grammatical differences between sentence types. The maintained verb form in the present progressive tense sentences (e.g., The black cat lap/s the milk) was the morphosyntactic feature of interest for comparing P600 responses as an indicator of error detection. Following each trial, responses and reaction times to a grammatical acceptability judgment task were collected and compared.

Results: Findings indicate distinct neurophysiological profiles between bidialectal and monodialectal speakers. Monodialectal speakers demonstrated a P600 response within 500-800ms following presentation of an AAE morphosyntax feature, indicating error detection; this response was not seen in the bidialectal group. Control sentences with non-contrasting grammar revealed no differences in ERP responses between groups. Behaviorally, bidialectal speakers showed greater acceptance of known dialectal variation and error (non-contrastive) sentence types compared to the monodialectal group.

Conclusions: ERP and behavioral responses are presented as preliminary evidence of dual-language representation in bidialectal speakers. Increased consideration of AAE language processing would enhance equity in the study of language at large, improving the work of clinicians, researchers, educators and policymakers alike.