Perceptual asymmetries in the development of lexical tone perception in Thai-learning children

Abstract

Discrimination of vowel and consonant pairs is influenced by their order, known as perceptual asymmetry, and recent research suggests a similar effect for lexical tones. This study tested whether discrimination of two consecutive tones is easier when a dynamic contour tone (e.g., rising/falling) precedes a static-level tone (e.g., low/high) than vice versa. Thai-speaking children aged 4, 6, and 8 years and adults completed an AX task with four tone pairs in dynamic–static and static–dynamic orders. Adults showed no perceptual asymmetry, possibly due to ceiling effects. However, children in all three age groups discriminated dynamic–static pairs better than static–dynamic pairs. Although tone discrimination improved across age groups, the magnitude of the dynamic–static over static–dynamic advantage remained stable. These findings reveal a dynamic–static bias in tone perception that emerges before age four and remains stable into the school years. Implications for segmental asymmetries and theories of speech perception are discussed.