Perceptual Boundary Shift in Native Consonants Caused by Second Language Learning

Previous research has demonstrated that short-term second language (L2) training can induce perceptual modifications in native language (L1) sound processing. The current study systematically investigated this phenomenon through experiments with native Chinese learners who had received short-term intensive Spanish training. The study comprised two experiments employing pre-test-training-post-test designs with distinct task configurations. Experiment A implemented a sequential protocol consisting of: Chinese consonant identification, Spanish consonant training and Spanish consonant identification tasks. Experiment B featured a modified design with: /p/-/w/ continuum identification and the Spanish training regimen identical to Experiment A. Results revealed that: four days of Spanish training altered L1 consonant perception, with /w/ showing the most notable variability among affected consonants; and the categorical boundary for /w/ perception shifted significantly in terms of formant rise time, while boundary width remained stable. These findings provide robust evidence that brief L2 exposure can induce rapid drift in L1 phonological categories, particularly affecting boundary positions in categorical perception without altering perceptual sharpness.