The impact of vocal affect in infant-directed speech on speech sound category development (VAICA)

This project studies how socioemotional aspects of language such as vocal affect in parents’ infant-directed speech impact infant language development in the first year of life.

During this time, speech sound categories mature through exposure to distributions in the surrounding language environment.

Study 1 tests whether vocal affect impacts distributional learning of variation in the speech signal in the immediate context. Study 2 tests whether vocal affect impacts speech sound category development in general.

Vocal affect is assumed to impact language development via heightened infant arousal, engaging the infant in parent speech input and thereby enhancing learning, as well as by increasing the salience of information in the speech signal.

The project combines behavioral methods such as the preference looking paradigm, the distributional learning paradigm, and spontaneous parent-infant play sessions at the lab as well as daylong audio recordings at the family home with electroencephalography (EEG) to assess speech sound category maturation in the brain.

The project will yield novel insights in the relationship between vocal affect and speech sound category development, with the potential to show how affective quality of infant-directed speech impacts language development at one of its foundations.

Being able to show language learning mechanisms in detail is relevant for child development in general due to the universal nature of socioemotional factors.