Researchers at the National Institutes of Health, and in Germany, Italy and Japan, showed seven men and nine women a series of images while recording their brain activity with a functional magnetic resonance imaging scanner. The participants looked at images of puppy and kitten faces, full-grown dogs and cats, human infants and adults.
The researchers recorded participants' brain activity -- the participants did not speak or move, yet their brain activity was typical of patterns preceding such actions as picking up or talking to an infant. The activity pattern could represent a biological impulse that governs adults' interactions with small children.
The pattern did not appear when the participants looked at photos of adults or animals -- even baby animals. The researchers concluded the pattern is specific to seeing human infants.
The findings raise the possibility that studying this activity will yield insights not only into the caregiver response, but also when the response fails, such as in instances of child neglect or abuse.
"These adults have no children of their own," senior author Marc H. Bornstein, head of the Child and Family Research Section of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in a statement. "Yet images of a baby's face triggered what we think might be a deeply embedded response to reach out and care for that child."
Their findings were published in the journal NeuroImage.