Regressive cross-linguistic influence in multilingual speech rhythm: The role of language similarity

While previous work on multilingual speech rhythm has found evidence of progressive cross-linguistic influence of a first or second language (L1, L2) on a third language (L3), regressive cross-linguistic influence (rCLI) in rhythm remains understudied. In the current study, we tested the roles of order of acquisition and of language similarity in shaping rCLI from syllable-timed Spanish as L3 to stress-timed English and German as L1/L2. In a picture narration task, adult sequential trilinguals (L1 English-L2 German-L3 Spanish, L1 German-L2 English-L3 Spanish) and sequential bilingual controls (L1 English-L2 German, L1 German-L2 English) produced semi-spontaneous speech in each of their languages, which was analyzed in terms of the rhythm metric VarcoV. Results showed evidence of rCLI in English (the typologically more similar language to Spanish) but no evidence of rCLI in German; however, rCLI in English was found only when English was the L1. On the basis of these findings, we propose the Similarity Convergence Hypothesis (SCH), which claims that previously acquired languages that are more similar to a later-acquired language are relatively more vulnerable to rCLI from this language. © 2023 John Benjamins Publishing Company