Lullabies work just as well for soothing a baby to sleep if it is in their native language or a completely foreign dialect, a new study claims.
In trials, Harvard University researchers found infants relaxed when played lullabies that were unfamiliar and in a foreign language, including French and Gaelic.
They found that regardless of if it was Frère Jacques or Twinkle, Twinkle, Little Star, the infant responded in the same way.
Academics saw universal drops in heart rate and higher electrodermal activity – a measure of excitement based on the skin’s electrical resistance.
The study suggests the melody carried by the lyric is what babies enjoy, not familiarity with the words themselves.
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Researchers at Harvard’s Music Lab have determined that American infants relaxed when played lullabies that were unfamiliar and in a foreign language. Pictured, baby Theo demonstrates the method for measuring physiological responses to lullabies
The finding supports the idea that there is an ‘evolutionary function’ of music rather than it just being a byproduct of language.
‘There’s a longstanding debate about how music affects listeners as a result of both prior experiences with music and the basic design of our psychology,’ said Samuel Mehr at Harvard’s Music Lab.
‘Common sense tells us that infants find the lullabies they hear relaxing – is this just because they’ve experienced their parents’ singing before and know it means they’re safe and secure or is there also something universal about lullabies that produces these effects, independently of experience?’
To measure the infants’ relaxation responses to the recordings, the researchers focused on pupil dilation (pictured) and heart rate changes, among other factors
The study was conducted at Harvard’s Music Lab, which focuses on the psychology of music from infancy to adulthood.
In the experiment, each infant watched an animated video of two characters singing either a lullaby or a non-lullaby.
The songs were chosen through a previous Music Lab study in which adults rated how likely a foreign unfamiliar song was to be a lullaby.
The selection included a total of 16 lullabies and other songs originally produced to express love, heal the sick or encourage dancing.
Languages like Scottish Gaelic, Hopi, and Western Nahuatl, and regions including Polynesia, Central America, and the Middle East were represented.
To measure the infants’ relaxation responses to the recordings, the researchers relied on pupil dilation, electrodermal activity, heart rate changes, frequency of blinking and gaze direction.
Generally, the heart rate of the babies slowed, their pupils widened and more electrodermal activity was recorded in response to the unfamiliar lullabies.
The new findings indicate that infants respond to universal elements of songs, despite the unfamiliarity of their melodies and words.
‘Melody is one of the things that sticks out for lullabies,’ said study author Connie Bainbridge.
‘In comparison, in a lot of other song types, such as dance songs, you would see rhythm as being more of a driving force.’
Separately, researchers asked parents to listen to both types of song and choose which they would use to soothe their infant.
Virtually all new parents quickly discover that a lullaby will in fact help an infant unwind, but they might surprised to learn that babies aren’t fussy about the language
They almost always chose the lullaby, indicating that they also recognised the universal elements of the lullaby, even subconsciously.
‘Calming a fussy infant is an urgent matter for parents – those of us with kids might be particularly sensitive to the acoustic features that appear universally in lullabies, as these may be most likely to calm our infants efficiently,’ said Mehr.
The researchers had to act quickly because of the limited attention spans of their subjects.
Most babies paid attention for about five minutes before getting distracted.
The 16 songs selected for the experiment came from the Natural History of Song Discography, and included lullabies and other songs originally produced to express love, heal the sick, or encourage dancing
‘In an ideal world, we would play babies a dozen songs that are lullabies and a dozen songs that are not lullabies and gather a lot of data from each infant,’ said study author Mila Bertolo at Harvard.
‘But an infant’s attention span is short, so the experiment is short too.’
The team plan to find the specific acoustical elements of a lullaby that encourage relaxation and how singing interacts with other activities.
The researchers also predict that the results could be replicated with a different group of subjects from another culture.
The study has been published in Nature Human Behaviour.