L1 Attrition in Instructed Settings: Evidence from L1 Spanish–L2 English Bilinguals

This study investigates first language attrition in the interpretation and processing of relative clause attachment ambiguities among instructed late sequential L1 Spanish–L2 English bilinguals. Traditionally, L1 attrition has been associated with limited L1 use and exposure, along with extensive naturalistic immersion. This study questions these conditions as prerequisites of attrition, examining bilinguals who live in an L1 environment but are extensively exposed to their second language in an instructed, classroom-based university setting. Bilinguals were compared with two native control groups of Spanish and English monolinguals. Results from a picture selection task reveal L1 attrition effects in instructed bilinguals, as they rely less frequently on their L1-preferred disambiguation strategy, i.e., high attachment, when resolving ambiguous relative clauses, particularly in comparison to Spanish monolinguals. Instructed bilinguals also exhibit higher processing when processing ambiguous sentences. Additionally, the study explores whether language dominance modulates attrition effects. We consider the implications of these findings for our understanding of grammatical attrition across different input contexts.