Cross-linguistic perceptual learning in advanced second language listeners

An issue of long-standing interest is whether phones, which correspond to each other phonologically but differ phonetically across two languages, are distinct in the minds of bilinguals and second language learners. Here, we ask whether listeners maintain separate representations for phonetically highly similar phonemes common to two languages even though this might seem inefficient. One way to address this question is to induce a change in the representation of phonemes in one language, and to test whether the other language is also affected. We carried out two perceptual learning studies, one with intermediate to advanced L1 English learners of German and one with intermediate to advanced L1 German learners of English, to probe the relationship between listeners\u27 representations for the /f-s/ contrast in English and in German. We found cross-linguistic perceptual learning effects extending from English to German in both studies, though the effect sizes for perceptual learning in English and German differed. Based on these findings, we propose that phonetically highly similar phonemes common to listeners\u27 L1 and L2 have separate yet interconnected mental representations for speech perception