Mothers don't talk as clearly to their offspring as they do to adults

A new study has shown that mothers surprisingly speak less clearly to their babies than they do to adults.

The research represents a collaborative effort between scientists from the RIKEN Brain Science Institute (BSI) in Japan and researchers from the Laboratoire de Sciences Cognitives et Psycholinguistique in Paris. Using speech samples, the two teams 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, who studied speech of 22 Japanese mothers speaking both to their child and to an adult, found that mothers spoke slightly less clearly when talking to their child than to the experimenter.

Alejandrina Cristia, one of the Parisian scientists said that the finding was important because it challenged 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.

As per their results, at least for learning sound contrasts, the secret to infants' language-learning genius may be in the infants themselves. The fact that they are able to pick up sounds from input that was less clear than that used by adults with each other makes this accomplishment all the more remarkable, explained Andrew Martin, the first author of the paper.

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.

The research is published in Psychological Science.