Sharing a smile can synchronize mom’s and baby’s heartbeat: study

Affectionate face-to-face interaction between a mother and her baby caused the heart rhythm of mother and baby to coordinate “within lags of less than one second.”
Thu Dec 8, 2011 - 2:48 pm EST

December 8, 2011 ( - According to a study published this month, mothers can synchronize with their babies’ heartbeats just by smiling at them, reports.

Researchers at Bar-Ilan University in Israel monitored the “cardiac output” of women and their three-month-old infants during face-to-face interactions.

Their report, published in the scientific journal Infant Behavior and Development revealed that affectionate face-to-face interaction caused the heart rhythm of mother and baby to coordinate “within lags of less than one second.”


The researchers noted: “The concordance between maternal and infant biological rhythms increased significantly during episodes of affect and vocal synchrony compared to non-synchronous moments. Humans, like other mammals, can impact the physiological processes of the attachment partner through the coordination of visuo-affective social signals.”

The results lend further credibility to previous work by one of the Bar-Ilan researchers, Ruth Feldman, who has demonstrated the importance of “synchrony,” the attunement between parent and child demonstrated during affectionate interactions, in multiple studies.

A 2007 study published by Feldman correlated mother-infant synchrony to the development of a child’s sense of morality. She found that the degree of synchrony during infancy was a predictor for a child’s moral cognition and capacity for empathy in later years.

Feldman has also studied father-child synchrony, comparing and contrasting it with mother-infant synchrony in a 2003 study. She concluded that “both fathers and mothers are equally capable of engaging in second-by-second synchrony with their infant.”

However, her report found that each parent offers “different experiences,” and pointed to evidence that healthy child development requires the presence of two different-gendered parents. 

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