Contrary to the common perception that elders need to talk to babies in simpler words, new research suggests they may actually speak less clearly to their infants 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 Laboratoire de Sciences Cognitives et Psycholinguistique in Paris.
The two teams tested the hypothesis that parents pronounce sounds more distinctly when addressing children in an unconscious attempt to help them learn the sounds of the language.
“Our results suggest that 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 is less clear than that used by adults with each other makes this accomplishment all the more remarkable,” explained first author Andrew Martin from the Paris lab.
They recorded the speech of 22 Japanese mothers speaking both to their child and to an adult. Then they extensively annotated these recordings with detailed transcriptions of each mother’s speech.
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’.
Surprisingly, mothers spoke slightly less clearly when talking to their child than to the experimenter, found the study.
Mothers are focusing on other goals within and beyond language like communicating emotions or on engaging the child’s attention and this is the reason why they may not use simpler words with kids.
“This finding is important 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,” said Alejandrina Cristia, one of the Parisian scientists.
The findings appeared in the journal Psychological Science.
Andrew Martin, Thomas Schatz, Maarten Versteegh, 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, January 2015 DOI: 10.1177/0956797614562453