Does perceptual learning in speech reflect changes in phonetic category representation or decision bias?
Recent studies show that perceptual boundaries between phonetic categories are changeable with training (Norris, McQueen, & Cutler, 2003). For example, Kraljic and Samuel (2005) exposed listeners in a lexical decision task to ambiguous /s-integral/ sounds in either s-word contexts (e.g., legacy) or integral-word contexts (e.g., parachute). In a subsequent /s/-/integral/ categorization test, listeners in the /s/ condition categorized more tokens as /s/ than did those in the /integral/ condition. The effect--termed perceptual learning in speech--is assumed to reflect a change in phonetic category representation. However, the result could be due to a decision bias resulting from the training task. In Experiment 1, we replicated the basic Kraljic and Samuel (2005) experiment and added an AXB discrimination test. In Experiment 2, we used a task that is less likely to induce a decision bias. Results of both experiments and signal detection analyses point to a true change in phonetic representation.
Clarke-Davidson
Constance M
CM
University at Buffalo, State University of New York, Buffalo, New York, USA. cmclarke@ualberta.ca
Luce
Paul A
PA
Sawusch
James R
JR
D002675:Child, Preschool; D003657:Decision Making; D005260:Female; D006801:Humans; D008297:Male; D010465:Perception; D010700:Phonetics; D013060:Speech; D014706:Verbal Learning