Phonetic recalibration only occurs in speech mode

Upon hearing an ambiguous speech sound dubbed onto lipread speech, listeners adjust their phonetic categories in accordance with the lipread information (recalibration) that tells what the phoneme should be. Here we used sine wave speech (SWS) to show that this tuning effect occurs if the SWS sounds are perceived as speech, but not if the sounds are perceived as non-speech. In contrast, selective speech adaptation occurred irrespective of whether listeners were in speech or non-speech mode. These results provide new evidence for the distinction between a speech and non-speech processing mode, and they demonstrate that different mechanisms underlie recalibration and selective speech adaptation.