They said that frequent and erratic interruptions to baby care could affect brain development.

London - Babies understand what their mothers say, even when they speak in a language their children have never heard before, scientists claim.

They found one-year-olds reacted in exactly same way to their mother’s voice regardless of whether she was speaking in English or Greek.

It proves what mothers have long known - that babies pick up on tone of voice rather than the words.

The researchers, from Cardiff University’s School of Psychology, observed babies as they watched their mothers perform actions with toys using the English words “whoops” and “there”.

The mothers then repeated the process in Greek, using the same tone of voice. The academics found that the babies had the same reaction to both languages.

Study leader Dr Merideth Gattis said: “What this work showed is that children could have access to understanding using simply the tone of voice. We did ‘whoops’ and ‘there’ in two languages and got exactly the same results - whether in English or Greek, which none of the children understood.”

She added that children respond to “tone” clues in their parents’ speech from an early age - and what they say is less important than how they say it.

The researchers, who published their findings in the journal Cognitive Development, studied 84 babies aged 14 to 18 months. - Daily Mail