Babies like it when you imitate them

A baby smiles and laughs. You smile and laugh right back. The baby pounds his tiny, curled-up fist on the table. You mirror his action, lightly pounding yours back.

This imitation game comes naturally. It's a simple way for parents to have fun with their tiny humans. And new research shows that babies not only realize that adults are imitating them, but they also seem to enjoy it.

For the study, a researcher from Lund University in Sweden met 6-month-old babies in their homes and played with them in four different ways. She either imitated everything the babies did in mirror-like fashion, imitated it as a reverse mirror, imitated the actions while keeping an expressionless face, or responded with a different action when the babies acted. This is often how parents react to babies, and is called contingent responding. They respond to what a child might need or want, but they don't imitate their actions.

In the study, the babies looked and smiled longer and tried to approach the adult more often when their actions were being most closely mirrored.

"Imitating young infants seems to be an effective way to catch their interest and bond with them. The mothers were quite surprised to see their infants joyfully engaging in imitation games with a stranger, but also impressed by the infants' behaviors," lead author Gabriela-Alina Sauciuc, researcher at Lund University, said in a statement.

While the babies were playing with the researcher, they also exhibited some testing behavior. For example, if the baby hit the table just once and the researcher imitated the action, then the baby would hit the table several times, carefully watching the researcher for a response. During instances when the researcher showed no emotions while imitating the baby, the babies still appeared to recognize that they were being imitated and they responded with testing behavior with the researcher.

"This was quite interesting. When someone actively tests the person who is imitating them, it is usually seen as an indication that the imitated individual is aware that there is a correspondence between their own behavior and the behavior of the other," Sauciuc said. The results were published in the journal PLOS One.

Playing with babies

Researchers used information from 16 babies for the study. (Twelve other babies took part in the experiment but their information was excluded because they fussed too much, there was an equipment malfunction, or they were interrupted by parents, siblings, or the mail carrier.)

The babies were tested in their own homes, sitting on their mother's laps. The researcher came in, smiling at the baby, making eye contact, and calling the baby's name. Each of the four testing phases lasted about two minutes and was stopped if the baby fussed for more than 30 seconds. But the baby was allowed to stand up, to withdraw from the situation, and even pull the researcher's hair.

In the mirror and reverse-mirror stages, the researcher imitated all the actions, facial expressions, and noises made by the baby. In the third stage, the researcher just copied all the baby's body actions. In the contingent response last stage, the researcher responded whenever the infant acted, but didn't mimic the baby's action. The researcher rotated between one of several actions including waving while saying the Dutch equivalent of "hello," opening her mouth while making a popping sound, and tapping her face.

The researchers found that all the babies showed signs that they realized they were being imitated. They did so by giving social signals such as smiling and increased attention to the adult who was testing them.

Scientists have speculated that imitation is key for babies in learning about how to act with others, and sharing actions is linked with sharing feelings. But there isn't a lot of research to back up those theories.

"By showing that 6-month-old infants recognize when they are being imitated, and that imitation has a positive effect on interaction, we begin to fill up this gap," Sauciuc said. "We still have to find out when exactly imitation begins to have such effects, and what role imitation recognition actually plays for babies."