# Primacy of mouth over eyes to perceive audiovisual Mandarin lexical tones

## TL;DR

The study found that people focus more on the mouth than the eyes when identifying Mandarin tones, especially in noisy conditions.

## Contribution

It reveals the mouth's primacy over eyes in audiovisual lexical tone perception.

## Key findings

- Participants gazed more at the mouth than the eyes during tone identification.
- Gaze duration at the mouth increased in adverse acoustic conditions.
- Chinese and English speakers showed similar eye movement patterns.

## Abstract

The visual cues of lexical tones are more implicit and much less investigated than consonants and
vowels, and it is still unclear what facial areas contribute to facial tones identification. This study
investigated Chinese and English speakers’ eye movements when they were asked to identify
audiovisual Mandarin lexical tones. The Chinese and English speakers were presented with an
audiovisual clip of Mandarin monosyllables (for instance, /ă/, /à/, /ĭ/, /ì/) and were asked to identify
whether the syllables were a dipping tone (/ă/, / ĭ/) or a falling tone (/ à/, /ì/). These audiovisual
syllables were presented in clear, noisy and silent (absence of audio signal) conditions. An eye-tracker
recorded the participants’ eye movements. Results showed that the participants gazed more at the
mouth than the eyes. In addition, when acoustic conditions became adverse, both the Chinese and
English speakers increased their gaze duration at the mouth rather than at the eyes. The findings
suggested that the mouth is the primary area that listeners utilise in their perception of audiovisual
lexical tones. The similar eye movements between the Chinese and English speakers imply that the
mouth acts as a perceptual cue that provides articulatory information, as opposed to social and
pragmatic information.