How Perceptual Learning Extends Across Vowels.

Speakers' perception of phonemes can be shifted based on hearing tokens of them with altered acoustic characteristics, and those shifts are extended to phonemes not heard during exposure. The patterns of extension from one vowel to others can help clarify the phonological representation of vowels and the processes that underlie extension of acoustic shifts. Three perceptual learning tasks tested how exposure to shifted F1 or F2 in a single vowel quality in American English influences other vowels with a range of characteristics, and how differences between dialects interact with those patterns of extension. In Experiment 1, shifted F1 in /ɪ/ exposure items produced perceptual shifts in the boundary between several high and mid vowels, as well as the /ε-æ/ boundary. In Experiment 2, shifted F2 in /u/ exposure items produced perceptual shifts in the boundary between front and back vowels. In Experiment 3, shifted F2 in /ε/ or /ei/ produced different patterns; shifted /ei/ only impacted the /ou-ei/ boundary, while shifted /ε/ impacted /ʌ-ε/ and /ʊ-ɪ/. The results can be explained by shifts in perception extending to vowels that share phonological features which are linked to the manipulated acoustic characteristic. However, the results are also largely consistent with extension based on acoustic similarity. There was little evidence for the listener's dialect affecting patterns of extension.