Grammatical restructuring in L3 development: a longitudinal study of Negative Concord in L3 Spanish by Japanese–English bilinguals

The present study aims to explore the extent to which linguistic experience in the transferred language modulates the rate of grammatical development in third language (L3) acquisition. To do so, we test a group of Japanese–English bilinguals ( n = 22) who were acquiring Spanish as their third language. Participants were tested at two different time points on their knowledge of negative concord items in L3 Spanish and first language (L1) Japanese, and negative quantifiers in second language (L2) English, using a grammaticality judgement task. Participants were first tested (TIME 1) after 2.5 months of intensive classroom instruction exposure in Spanish (96 hours) and tested again (TIME 2) after 10 months in Spanish only with around 800 hours of accumulated classroom exposure. TIME 1 results showed that participants treated Spanish negative concord items similarly to English negative quantifiers, suggesting evidence of English transfer at the initial stages of acquisition. TIME 2 results showed traces of development that were modulated by linguistic experience in the transferred language, as predicted by the cumulative input threshold hypothesis (CITH). TIME 2 results also show instances of both target-like and non-target-like development in L3 Spanish, which we attribute to subsequent influence from Japanese into Spanish throughout development.