The psycholinguistic literature suggests that the length of a to-be-spoken phrase impacts the scope of speech planning, as reflected by different patterns of speech onset latencies. However, it is unclear whether such findings extend to first and second language (L1, L2) speech planning. Here, the same bilingual adults produced multi-phrase numerical equations (i.e., with natural break points) and single-phrase numbers (without natural break points) in their L1 and L2. For single-phrase utterances, both L1 and L2 were affected by L2 exposure. For multi-phrase utterances, L1 scope of planning was similar to what has been previously reported for monolinguals; however, L2 scope of planning exhibited variable patterns as a function of individual differences in L2 exposure. Thus, the scope of planning among bilinguals varies as a function of the complexity of their utterances: specifically, by whether people are speaking in their L1 or L2, and bilingual language experience.
