Researchers have found that infants and adults are likely to be on the same wavelength, experiencing similar brain activity in the same brain regions during play.
The research team from Princeton University has conducted the study on how baby and adult brains interact during natural play, and they found measurable similarities in their neural activity.
"Previous research has shown that adults' brains sync up when they watch movies and listen to stories, but little is known about how this 'neural synchrony' develops in the first years of life," said the study's first author Elise Piazza from Princeton University.
According to the findings, published in the journal Psychological Science, the research team has posted that neural synchrony has important implications for social development and language learning.
Studying real-life, face-to-face communication between babies and adults is quite difficult.
But to study real-time communication, the researchers developed a new dual-brain neuroimaging system that uses functional near-infrared spectroscopy (fNIRS), which is highly safe and records oxygenation in the blood as a proxy for neural activity.
The setup allowed the researchers to record the neural coordination between babies and an adult while they played with toys, sang songs and read a book.
The same adult interacted with all 42 infants and toddlers who participated in the study.
Of those, 21 had to be excluded because they "squirmed excessively," and three others flat-out refused to wear the cap, leaving 18 children, ranging in age from nine months to 15 months.
The experiment had two portions. In one, the adult experimenter spent five minutes interacting directly with a child -- playing with toys, singing nursery rhymes or reading Goodnight Moon -- while the child sat on their parent's lap.
In the other, the experimenter turned to the side and told a story to another adult while the child played quietly with their parent.
The caps collected data from 57 channels of the brain known to be involved in prediction, language processing and understanding other people's perspectives.
When they looked at the data, the researchers found that during the face-to-face sessions, the babies' brains were synchronised with the adult's brain in several areas known to be involved in high-level understanding of the world -- perhaps helping the children decode the overall meaning of a story or analyse the motives of the adult reading to them.
When the adult and infant were turned away from each other and engaging with other people, the coupling between them disappeared.
That fit with researchers' expectations, but the data also had surprises in store.
"We were also surprised to find that the infant brain was often 'leading' the adult brain by a few seconds, suggesting that babies do not just passively receive input but may guide adults toward the next thing they're going to focus on: which toy to pick up, which words to say," said study researcher Lew-Williams.