Babies and puppies share a surprising commonality: they both elicit a change in the way mothers speak to them. Mothers adjust their speech rate, pitch, and articulation when addressing these young ones.
Researchers from Virginia Tech, the École Normale Supérieure-PSL, and Pacific Lutheran University sought to understand the reasons behind this natural adaptation of maternal speech. Previous studies had shown that mothers spoke more clearly in the presence of babies or parrots, attributing this to teaching human language. However, other research contradicted this explanation, indicating that the clarity of mothers' speech was not always consistent.
Robin Panneton (Virginia Tech), Alejandrina Cristia (ENS-PSL), Caroline Taylor (Virginia Tech), and Christine Moon (Pacific Lutheran University) initially hypothesized that mothers spoke more clearly to babies than adults for pedagogical reasons or due to positive emotions associated with their presence.
To test these hypotheses, the scientists placed ten American mothers of six-month-old infants in a room. Their voices were recorded for ten minutes as they described three different objects to their infants, a puppy, and an adult. Participants described each object, highlighting its characteristics and sometimes its function. The recordings were then analyzed for positive valence, meaning their inherently pleasant quality.
The research team observed that mothers expressed more positive emotions towards infants and puppies than adults. Their articulation was significantly more accurate and refined when addressing these young ones compared to speaking to someone their own age. These findings clearly demonstrate that a mother's emotional state influences her articulation and tone of voice, as the researchers explain in their study, recently published in the Journal of Child Language.
These suprasegmental and phonetic modifications enhance the clarity of maternal speech, facilitating language processing. Several scientific studies suggest that "parentese," the way parents address their newborns, helps babies learn to speak, regulate their emotions, and even structure their social interactions.
Even more surprisingly, this language is shared by numerous cultures and communities worldwide, as revealed by a study published in 2022 in the journal Nature Human Behaviour. Forty scientists discovered that adults around the world speak to babies in a similar way after analyzing 1615 vocal recordings in 18 different languages from 410 parents originating from six continents.
Human mothers are not the only ones to change their way of speaking in the presence of their young. Female dolphins do the same, as do those belonging to the species of rhesus macaques and squirrel monkeys. This finding adds a new dimension to linguistic research on babies.