Perceptual learning for speech: Is there a return to normal

Recent work on perceptual learning shows that listeners phonemic representations dynami-cally adjust to reflect the speech theyhear (Norris,McQueen,&Cutler, 2003).We investigate how the perceptual systemmakes such adjustments, andwhat (if anything) causes the representations to return to their pre-perceptual learning settings. Listeners are exposed to a speaker whose pro-nunciationof aparticular sound (either /s / or /S/) is ambiguous (e.g., halfwaybetween /s / and /S/). After exposure, participants are tested for perceptual learning on two continua that range from /s / to /S/, one in the Samevoice they heardduring exposure, andone in aDifferent voice. Toassess how representations revert to their prior settings, half of Experiment 1s participants were tested immediately after exposure; the other half performed a 25-min silent intervening task. The per-ceptual learning effect was actually larger after such a delay, indicating that simply allowing time to pass does not cause learning to fade. The remaining experiments investigate differentways that the systemmight unlearn a persons pronunciations: listeners hear the Same or aDifferent speak-er for 25 min with either: no relevant (i.e., good) /s / or /S / input (Experiment 2), one of the rel-evant inputs (Experiment 3), or both relevant inputs (Experiment 4).The results support a viewof phonemic representations as dynamic and flexible, and suggest that they interact with both high