Impaired categorical perception of lexical tones in Mandarin-speaking congenital amusics.

The degree to which cognitive resources are shared in the processing of musical pitch and lexical tones remains uncertain. Testing Mandarin amusics on their categorical perception of Mandarin lexical tones may provide insight into this issue. In the present study, a group of 15 amusic Mandarin speakers identified and discriminated Mandarin tones presented as continua in separate blocks. The tonal continua employed were from a high-level tone to a mid-rising tone and from a high-level tone to a high-falling tone. The two tonal continua were made in the contexts of natural speech and of nonlinguistic analogues. In contrast to the controls, the participants with amusia showed no improvement for discrimination pairs that crossed the classification boundary for either speech or nonlinguistic analogues, indicating a lack of categorical perception. The lack of categorical perception of Mandarin tones in the amusic group shows that the pitch deficits in amusics may be domain-general, and this suggests that the processing of musical pitch and lexical tones may share certain cognitive resources and/or processes (Patel 2003, 2008, 2012).