# Facial affect and arousal as a complement to gaze measures in infant speech sound perception studies

## TL;DR

The study shows that analyzing infants' facial expressions can help understand how they perceive native and non-native speech sounds, complementing gaze measures.

## Contribution

The novel use of automated facial affect analysis to study perceptual attunement to speech sounds in infants.

## Key findings

- Valence and arousal decreased during habituation to speech sounds.
- Positive affect increased during habituation, with differences between native and non-native stimuli.
- Reduced negative affect was linked to better discrimination of native speech sounds.

## Abstract

This study explores infant facial expressions during visual habituation to investigate perceptual attunement to native and non-native speech sounds. Using automated facial affect analysis based on Facial Action Units, we analyzed valence, arousal, positive affect, and negative affect during the experiment. Valence and arousal decreased with habituation, while positive affect increased, with differences between native and non-native stimuli. Facial affect showed links to discrimination outcomes, with better native discrimination linked to reduced negative affect. These findings highlight the potential of facial expression analysis as a complementary tool to gaze-based measures in early language development research.