Feeding a hungry baby can seem like one of the most basic tasks of parenthood, but right from the beginning, the way an individual baby eats, gains weight and grows is a complicated parent-child mix of behavior and biology.

Part of the equation is whether the baby is actually hungry, or whether parents are providing food at any sign of distress. Dr. Ian Paul, a professor of pediatrics and public health sciences at Penn State College of Medicine, is one of the leaders of the Insight Study, an intervention which started in 2011 to look at the effects of helping parents learn “responsive parenting” strategies that help them read their babies’ signals. “Many people tell mothers to feed on demand, but they never define what ‘on demand’ is,” he said.

In the intervention, he said, parents learn to recognize what is actually hunger, since hungry babies, of course, need to be fed, and they also learn alternative strategies for soothing babies who are crying for other reasons. A baby who is distressed but not particularly hungry will calm down if given a sweet liquid, which Dr. Paul said could lead to problems later on. “Their normal ability to regulate their emotions becomes overridden with a food reward to soothe them and that then projects later into life — when they are upset or depressed, food becomes the mechanism to soothe these emotions.”

In the intervention trial, parents are taught to try to calm a crying infant using strategies other than feeding, including swaddling, repositioning, playing white noise, and rocking, and they are also given information about how much crying is normal for babies at a given age.