Virtually all new parents quickly discover that a lullaby will in fact help an infant unwind, but they might be surprised to learn that babies aren’t fussy about the language.
Researchers at Harvard’s Music Lab have determined that American infants relaxed when played lullabies that were unfamiliar and in a foreign language. Their results were published in Nature Human Behaviour on Oct. 19.
“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, a Department of Psychology research associate and principal investigator at the 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?”
The new findings supported the latter hypothesis: Infants responded to universal elements of songs, despite the unfamiliarity of their melodies and words, and relaxed. The study was conducted in 2018 and 2019 at the 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. To measure the infants’ relaxation responses to the recordings, the researchers focused on pupil dilation, heart rate changes, electrodermal activity (a measure of “arousal” or excitement, from electrical resistance of the skin), frequency of blinking, and gaze direction as indicators of relaxation or agitation. Generally, the infants experienced a decrease in heart rate and pupil dilation, and attenuated electrodermal activity in response to the unfamiliar lullabies.
The researchers had to act quickly because of their subjects’ limited attention spans; most babies could pay attention for about five minutes before getting distracted.
“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. But an infant’s attention span is short, so the experiment is short too,” said Mila Bertolo, co-first author of the research.
Researchers played infants music from around the world and found they relaxed more in response to lullabies than other types of songs. Can you identify which song is the lullaby in the clips below?
Clip 2: Healing song from the Seri of Mexico.