Flexibility and Stability in Lexical Tone Recalibration: Evidence from Tone Perceptual Learning.

Listeners adjust their perception of sound categories when confronted with variations in speech. Previous research on speech recalibration has primarily focused on segmental variation, demonstrating that recalibration tends to be specific to individual speakers and situations and often persists over time. In this study, we present findings on the perceptual learning of lexical tone in Standard Chinese, a suprasegmental feature signaled primarily through pitch variations to distinguish morpheme/word meanings. Native speakers of Standard Chinese showed a recalibration of tone category boundaries immediately following exposure to ambiguous tonal pitch contours. However, this recalibration effect significantly weakened after 12 hours. Furthermore, participants trained at night did not exhibit delayed stabilization, a phenomenon commonly observed during sleep-induced consolidation. Our results replicate previous findings and provide new evidence suggesting that while our perceptual system can flexibly adapt to real-time sensory inputs, subsequent consolidation processes, such as those occurring during sleep, may exhibit selectivity and, under certain conditions, may be ineffective.