Study finds adults speak differently to babies in at least 10 languages

By Stephen Beech

Baby talk is real with adults speaking differently to tots in at least 10 different languages, reveals new research.

The modified speech moms and other adults often use when speaking to babies is formally referred to as infant-directed speech, or IDS.

Scientists say it often differs from adult-directed speech, or ADS, in both pitch and vocabulary.

But one component of IDS that remains controversial is the exaggeration, or hyperarticulation, of vowel sounds.

Some experts contend that vowel exaggeration produces clearer speech sounds that are easier for babies to process, but studies conflict on whether or not vowel hyperarticulation is actually present in IDS.

An international team of researchers analyzed the existing research on vowel hyperarticulation in IDS to determine whether or not that specific type of speech exaggeration occurs in IDS.

Before the analysis, one group of studies suggested that adults particularly exaggerate the vowels “a”, “i”, and “u” when speaking to babies, making vowels easier to perceive and potentially enabling word learning.

In contrast, other studies had not detected the consistent exaggeration of vowels in IDS, suggesting that baby talk may instead be a by-product of smiling or some other positive effect.

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Study first author Dr. Irena Lovčević said: “We decided to conduct a meta-analysis on all studies done on this topic to understand if vowel exaggeration is a feature of speech directed to babies, and if so, which factors lead to it and to the observed differences in existing research."

The analysis of 55 previous studies was published in the journal Psychological Bulletin.

Dr. Lovčević, of the International Research Centre for Neurointelligence (WPI-IRCN) at The University of Tokyo, Japan, said: “Our meta-analysis confirms that mothers exaggerate vowels in speech directed to babies in at least 10 languages.

"However, our results also point to the diversity of methods used in the existing research.

"Hence, we want the readers, especially speech acquisition researchers, to carefully consider and document the methodological decisions in their research and avoid the generalization from one language to another or one method to another."

The research team noted that differences in hyperarticulation across languages were difficult to detect due to smaller sample sizes for less represented languages.

After establishing the presence of vowel hyperarticulation in IDS, the research team now want to learn more about other aspects of infant language development.

Dr Lovčević said, “The next step is further examination of different factors influencing language development in babies, with special focus on modifiable factors from babies’ immediate environment, such as the amount of speech that babies are exposed to and the qualities of vocal caregiver-baby interactions."

She added, "How babies learn to speak without so much effort is still a big puzzle, so my goal is to contribute to solving this puzzle."