As any mother can attest, hearing her child cry, especially in infancy, evokes a powerful response. A mother's body responds to this cry in many ways. If she is breastfeeding and hears a baby cry, her milk will immediately start to flow. Other responses can be anxiety, or a need to rush to the baby and soothe whatever is making the infant cry.
Researchers at the Eunice Kennedy Shriver National Institute of Child Health and Human Development wanted to know if a mother's response to an infant's cry is the same in different cultures. Child-rearing practices vary significantly from country to country. In the United States, many parents feel that children eventually need to "cry it out" when waking at night and in other countries, an infant will sleep in the same bed with mom and dad, often until they reach school age.
Using brain imaging and behavioral observations, the team investigated the underlying brain activity when a mother hears a baby cry. The scans conducted were functional MRIs (fMRI) that show brain activity while the participant is performing a task, reading words or viewing something. Anything that the study volunteer sees or hears during an fMRI scan will show up in the MRI in real time. These types of scans can pinpoint which areas of the brain are active in response to specific stimuli.
To get a broad cross-section of information the project involved study volunteers in 11 countries (France, Argentina, Brazil, Italy, Kenya, Cameroon, the United States, Belgium, Israel, South Korea and Japan.) In total there were 684 mothers in the study sample. Researchers observed the moms and babies for an hour at their homes, to record how each mother and baby interacted. The babies were all five months of age at the time of the study. What the researchers were looking to record what each mother did when their baby would cry. Did they respond by talking to the baby, picking up the child, feeding or holding or distraction?
When looking at the scans of the mothers as they heard their child cry, they found common brain areas were consistently active, in both first-time mothers and experienced moms. The brain regions seen were the supplementary motor area which processes the intent to move or speak, the superior temporal regions that process sound and the inferior frontal area which is related to the production of speech. Each mom, when hearing her baby cry, had virtually the same brain activity which spurred her to move, speak and respond to the child.
The researchers concluded that mothers are inherently "hard-wired" to hear and respond to an infant's cry. While parenting techniques vary across cultures, the urge to comfort a crying baby is the same, as far as brain activity. The study also confirmed earlier research which showed that men and women respond differently to a fussing baby. In the video below, watch how one dad gets a baby to stop crying.