Though speech and voice are known to be a source of comfort, there has been no scientific evidence to show whether they affect behavior. Neurohormones, such as oxytocin, are thought to be responsible for positive feelings like love and attachment, especially between a mother and her children. This study looked at female children under stress when they were comforted by either their mothers’ physical or vocal presence. Results showed that both groups were equally comforted with high levels of oxytocin released in the brain. Authors conclude that “vocalizations may be as important as touch” when it comes to “social bonding in our species.”
“Studies on social behavior have shown that the basis of social fitness lies in the quality and strength of relationships between mother and infant.” However, the exact mechanism that underlies these relationship behaviors is still unclear. It is known that the brain hormone, oxytocin, is released in order to establish relationships between a mother and her child. Animal studies have shown that vocal stimuli from the mother may be essential in development of the bond, but there is lack of human evidence in this respect. Authors tried to assess if girl children under stress could be soothed by their mother’s voice alone, as detected by release of oxytocin in their child’s brain.
* The study included a total of 61 girls aged between 7 and 12 years and their mothers.
* The children were placed in a stressful condition that involved facing an audience and solving math problems in front of them.
* After the stressful situation, they were (1) reunited with their mothers, (2) allowed to talk with their mothers on the phone, or (3) allowed to watch a non-related film clip.
* During the experiment their salivary level of the stress hormone, cortisol, was analyzed and urine levels of oxytocin were measured. The former detected the amount of stress and the latter indicated if they were soothed by the conversation with their mothers. The third group that was not reunited with their mothers served as the control group.
* Children participating in the stressful experiment all displayed high levels of stress hormones that indicated that they were indeed stressed.
* Oxytocin levels in urine were raised in children who received vocal or physical and vocal comforting from their mothers. Those in the control group showed no such rise.
* The comfort levels were maintained for as long as one hour after the stressful experience was over if the participants were allowed vocal or physical comforting by their mothers.
Authors suggest interpreting the results in an evolutionary context. Speech developed 400 million years ago, while oxytocin release in relation to pregnancy and delivery developed around 200 million years ago. The present hypothesis is that oxytocin release is the cause for maternal attachment. It may, however, be an evolutionary development in the reverse direction. In other words, speech-related attachment between mother and child may have caused the brain, through evolution, to release oxytocin. Authors suggest that further studies that explore voice as well as language and comfort may be warranted.
This study has shown that vocal comfort from the mother as well as her physical presence may release the attachment hormone, oxytocin, in the brain. The levels in both situations are similar, showing that touch and voice are both similarly effective in soothing a child under stress. This has implications for children who have not had biological parents to raise them or have been institutionalized early in their life. The abuse that they face and the poor health consequences that result may be prevented by offering vocal support to these children. This measure may also buffer stress and allow these children to develop a healthier psyche and deeper capacity for attachment and social bonding.
For More Information:
Social Vocalizations Can Release Oxytocin in Humans
Proceedings of the Royal Society, Biological Sciences, May 2010
By Leslie Seltzer; Toni Zieglr; University of Wisconsin-Madison, Madison, and Wisconsin National Primate Research Center, Madison, Wisconsin
*FYI Living Lab Reports Are Summaries of the Original Research.