Babies and puppies have a lot in common: apart from being small and cute, they prompt mothers to change the way they speak while addressing them, modifying their speech rate, pitch and, above all, elocution.
A team of researchers from Virginia Tech and Pacific Lutheran University in the United States and École Normale Supérieure-PSL in France set out to discover why mothers naturally adapt their speech when talking to infants.
Previous studies have shown that women who have had a child speak more clearly in the presence of a baby – or even a parrot. Scientists explained this by suggesting that these women were teaching them human language.
But other studies contradict this by saying the clarity of mothers’ speech is not systematic. As such, the US and French researchers posited that mothers spoke more clearly to babies than to adults either for educational purposes or because they felt positive emotions while interacting with them.
To test these hypotheses, they placed 10 US mothers of six-month-old children in a room. Their voices were recorded for 10 minutes as they talked to their infant, a puppy, and an adult about three different objects.
The participants described each object, talking about their characteristics and occasionally their function. These recordings were then analysed in terms of positive valence – that is, their intrinsically pleasant quality.
A universal form of language?
The team observed that mothers expressed more positive emotions towards babies and puppies than towards adults. Their articulation was much more correct and polished than when speaking to someone their own age.
These results suggest that a mother’s emotional state has an effect on her elocution and tone of voice, as the researchers explain in their study, recently published in the Journal of Child Language.
These modifications have the effect of increasing the clarity of maternal speech, which in turn facilitates language processing in the listener.
Indeed, several scientific studies suggest that “parentese” – the way parents address their newborns – helps babies learn to speak, regulate emotions, and even structure their social interactions.
What’s more, it’s a form of language that appears to be shared by many cultures and communities around the world, as revealed by a study published in the journal “Nature Human Behaviour” last year.
Forty scientists learnt that adults all over the world talk to babies in a similar way, after analysing 1,615 voice recordings in 18 different languages from 410 parents on six continents.
And human mothers aren’t the only ones to change the way they express themselves in the presence of their young: female dolphins do the same, as do female rhesus macaques and squirrel monkeys.