L1 knowledge and the perception of casual speech processes in L2

Casual speech processes appear in every language. We here examine how listeners deal with casual speech processes in a second language, in the light of the processes in their native language. We compared a match case, where a second-language process (/t/-reduction) also appears in native speech, with a mismatch case, where a second-language process (/r/-insertion) is absent from native speech. In each case, native and non-native listeners judged stimuli in which a given phoneme (in sentence context) varied along a continuum from absent to present. Second-language listeners in general mimicked native performance in the match case, but deviated significantly from native performance in the mismatch case. Together these results make it clear that the mapping from first to second language is as important in the interpretation of casual speech processes as in other dimensions of speech perception. Unfamiliar casual speech processes in a second language can delay correct interpretation of speakers' messages. Casual speech processes that are already familiar from native speech, however, are easy to cope with; indeed, our results even suggest that it is possible for subtle difference in their occurrence patterns across the two languages to be detected, and to be accommodated to in second-language listening.