Cognitive neuroscientist Merle Fairhurst and colleagues of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, knew that previous studies with adults show that a specific type of touch receptor is activated in response to a particular stroking velocity, leading to the sensation of “pleasant” touch. They hypothesized that this type of response might emerge as early as infancy.

Babies show unique physiological and behavioral responses to pleasant touch, which helps to cement the bonds between parent and child. For this study, Fairhurst and colleagues had infants sit in their parents’ laps while the experimenter stroked the back of the infant’s arm with a paintbrush. The results showed that the babies’ heart rate slowed in response to the brushstrokes when the strokes were of medium velocity; in other words, the touch of the medium-velocity brush helped to decrease their physiological arousal.

The infants’ slower heart rate during medium-velocity brushstrokes was uniquely correlated with the primary caregivers’ own self-reported sensitivity to touch. The more sensitive the caregiver was to touch, the more the infant’s heart rate slowed in response to medium-velocity touch.

The researchers noted that this link between caregiver and infant could be supported by both “nurture” and “nature” explanations. “Social touch is genetically heritable and therefore correlated between caregivers and infants,” Fairhurst said. According to the researchers, the findings “support the notion that pleasant touch plays a vital role in human social interactions by demonstrating that the sensitivity to pleasant touch emerges early in human development.”

This study indicates that a baby who is massaged regularly, receiving “pleasant” touch, will experience bonding in the infant’s very DNA, and is therefore more likely to naturally bond with his/her own children later in life. It also reminds us to teach the strokes in a way that is “medium velocity”; that is, not too light, not too heavy. In my experience, most parents err on the side of too light a stroke, and often need to be encouraged to be a little more strong as they massage. When they know that their baby responds better to a stronger stroke, they gain confidence. I often asked them to think of a cat licking her kittens; the “stroke” is just right; the kittens rely on the mother’s strength to feel grounded and cared-for.