Abstract
Research on infant vocal development has provided notable insights into vocal interaction with caregivers, elucidating growth in foundations for language through parental elicitation and reaction to vocalizations. A role for infant vocalizations produced endogenously, potentially providing raw material for interaction and a basis for growth in the vocal capacity itself, has received less attention. We report that in laboratory recordings of infants and their parents, the bulk of infant speech-like vocalizations, or “protophones”, were directed toward no one and instead appeared to be generated endogenously, mostly in exploration of vocal abilities. The tendency to predominantly produce protophones without directing them to others occurred both during periods when parents were instructed to interact with their infants and during periods when parents were occupied with an interviewer, with the infants in the room. The results emphasize the infant as an agent in vocal learning, even when not interacting socially and suggest an enhanced perspective on foundations for vocal language.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Competing interests: The authors have declared that no competing interests exist.
Data availability statement: The coded data that support the findings of this study are openly available in Open Science Framework at https://osf.io/hb834/. Due to the nature of this research, participants of this study did not agree for audio/video recordings to be shared publicly, so raw recording data is not available.
Minor revisions following reviewer comments: terminology changes, opinion study moved to appendix, supplemental files added