Moms can bring comfort, even at a distance, a new study finds.
The results show simply hearing mom's voice over the phone works just as well at calming nerves of stressed children as does a real-life pat on the shoulder.
The soothing effect is likely due to the release of the hormone oxytocin in the brain, the researchers say. This "love hormone" is known to quell stress, and is likely involved in social bonding, including that between a mother and a child.
Previous work has revealed this hormone was released during physical contact from mom.
"But it's clear from these results that a mother's voice can have the same effect as a hug, even if they're not standing there," said study researcher Leslie Seltzer, a biological anthropologist at the University of Wisconsin-Madison.
Stressed subjects
Seltzer tested a group of 61 girls, aged 7 to 12, by having them make an impromptu speech and solve a series of math problems in front of a panel of strangers, sending their hearts racing and levels of cortisol — a hormone associated with stress — soaring.
"Facing a challenge like that, being evaluated, raises stress levels for a lot of people," said study researcher Seth Pollak, a psychology professor and director of UW-Madison's Child Emotion Lab.
Once stressed, one-third of the girls were comforted in person by their mothers with hugs, an arm around the shoulders and other forms of physical affection. One-third of the girls watched an emotionally neutral 75-minute video. The rest were handed a telephone with mom on the line.
"The children who got to interact with their mothers had virtually the same hormonal response, whether they interacted in person or over the phone," Seltzer said.
For girls who interacted with mom, their levels of oxytocin, often called the "love hormone," rose significantly, and the stress-marking cortisol washed away. This reprieve from stress was also lasting.
"It stays well beyond that stressful task," Pollak said. "By the time the children go home, they're still enjoying the benefits of this relief and their cortisol levels are still low."
The same effect didn't show up for participants who watched the video.
What's going on?
The effect of mom's soothing voice might have a basis in human evolution. While males might respond to stress with a fight or flight response, it might make more sense for females with offspring in tow or slowed by pregnancy to use social bonding (through either touch or soothing words) as a stress remedy, Seltzer said.
The results were published May 12 in the journal Proceedings of the Royal Society B.
Seltzer is now testing the amount of oxytocin release with other communication methods — like text-messaging — and hopes to see the research spread out from human subjects.
"It's not just us, of course. Lots of very social species vocalize," she said. "On the one hand, we're curious to see if this effect is unique to humans. On the other we're hoping researchers who study vocal communication will consider looking at oxytocin release in other animals and applying it to broader questions of social behavior and evolutionary biology."
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