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Mothers don’t speak clearly to their babies

talking to babies

People have a distinctive way of talking to babies and small children: We speak more slowly, using a sing-song voice, and tend to use cutesy words like “tummy”. While we might be inclined to think that we talk this way because it is easier for children to understand, new research suggests that, surprisingly, mothers may actually speak less clearly to their infants than they do to adults.

Using speech samples the international team of researchers recorded, they set out to test the widely-accepted hypothesis that parents pronounce sounds more distinctly when addressing children in an unconscious attempt to help them learn the sounds of the language.

The researchers began by recording the speech of 22 Japanese mothers speaking both to their child and to an adult, and then extensively annotating these recordings with detailed transcriptions of each mother’s speech. Next, they applied a technique developed by the Paris team to measure the acoustic similarity between any two syllables, like ‘pa’ and ‘ba’, or ‘po’ and ‘bo’. The group used this process to examine the 118 most frequent syllable contrasts in both the adult- and child-directed speech. The results were surprising: Mothers spoke slightly less clearly when talking to their child than to the experimenter.

“This finding is important,” says Alejandrina Cristia, one of the Parisian scientists, “because it challenges the widespread view that parents do and should hyperarticulate, using very robust data and an analysis based on a study of 10 times as many syllable contrasts as previous work.”

“Our results suggest that, at least for learning sound contrasts, the secret to infants’ language-learning genius may be in the infants themselves,”explains Andrew Martin, the first author of the paper.

“The fact that they are able to pick up sounds from input that is less clear than that used by adults with each other makes this accomplishment all the more remarkable.” 

The researchers note that their interdisciplinary approach – which drew from developmental psychology, linguistics, and speech technology – provides a promising avenue for gaining a large-scale perspective on the nature of the input that children use to acquire their native language.

Of course, these new findings raise additional questions that the group hopes to explore. For example, why are mothers pronouncing sounds less clearly? The researchers suspect they are instinctively focusing on other goals within and beyond language – such as communicating emotions or on engaging the child’s attention – and slightly less-clear pronunciation is an inadvertent consequence of these other goals.

Collaborations with other labs around the world could help to answer another fascinating question: Do parents from other cultures do the same thing?

Andrew Martin, Thomas Schatz, Maarten Versteegh, Kouki Miyazawa, Reiko Mazuka, Emmanuel Dupoux, and Alejandrina Cristia. (2015). Kouki Miyazawa, Reiko Mazuka, Emmanuel Dupoux, and Alejandrina Cristia. Mothers Speak Less Clearly to Infants Than to Adults: A Comprehensive Test of the Hyperarticulation Hypothesis. Psychological Science : 10.1177/0956797614562453


6 responses

  1. This is pretty cool, motherese is fascinating!

    One of my favorite features is how parents often refer to themselves in the third person, and how this might — slightly paradoxically — help them learn first- and second-person pronouns. Maybe there is something similar happening with phoneme similarity?

    As for the generalization of this to other languages, I wouldn’t be surprised if it does; language acquisition can be surprisingly similar across languages — at least for pronouns.


    January 23, 2015 at 10:59 pm

    • I really like the link on third person parenting, thanks for those links and for taking the time to share them.


      January 25, 2015 at 11:39 am

  2. Rachel H

    I think this is a good article! I do agree that mothers speaks differently to babies than they normally do to adults. I think babies/children thinks and remembers words/languages more by the way she talks. Mothers may not pronounce their words clearly to their baby as they would speak to adults. They probably are more focused on both of their body movements and making sure their baby has a smile on their face and knowing that the mom is putting them in a good mood by using a good tone of her voice.

    I think parents from other cultures do the same thing, but some may do it different. But some of them may speak quicker than the other mothers by their culture and languages.


    January 24, 2015 at 7:30 pm

    • Thank you, I agree I think we focus more on communicating how we are feeling to children and less about what we are trying to say.


      January 25, 2015 at 11:40 am

  3. BriAna F.

    This is really interesting!

    I was once asked to babysit a baby whose mother requested that I spoke only in a way that I would to adults– This confused me; I’ve never even considered talking “clearly” to babies and young toddlers. But what is so different about communicating with a baby in regards to the tone of your voice? After giving it some thought, I’ve decided that I communicate to babies in such a way that would get their attention… positive attention at that. After reading this article I realize that statement could be true, but is it that way for everyone?

    Could it be possible that there is no clear and accurate way to measure such a question?


    January 24, 2015 at 9:19 pm

    • Could it be possible that there is no clear and accurate way to measure such a question? Definitely, a lot of things are subjective and at best not very easy to measure or quantify. The real underlying question is, is there an advantage to talking to babies using “baby talk” since it seem to me that we’ve evolved our speech patterns very specifically for children. If there is an advantage, what is it and why? In the end it could very well be that talking to a baby like you would an adult could have the opposite effect that you desired (or rather that the mom desired), but really it is a super complex question and one that won’t easily be answered.


      January 25, 2015 at 11:52 am

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