Does perceptual learning in speech reflect changes in phonetic category representation or decision bias?

• Published in: Perception & psychophysics Vol. 70; no. 4; p. 604
• Main Authors: Clarke-Davidson, Constance M, Luce, Paul A, Sawusch, James R
• Format: Journal Article
• Language: English
• Published: United States 01-05-2008
• Subjects: Child, Preschool; Decision Making; Female; Humans; Male; Perception; Phonetics; Speech; Verbal Learning
• ISSN: 0031-5117
• DOI: 10.3758/PP.70.4.604

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.