The takeaway for parents is that babies are very much aware of emotion, said Ross Flom, as associate professor of psychology at Brigham Young University and the co-author of the new study -- the first to study "peer matching" ability with children this young. The research was published in the journal "Infancy."
"It highlights the fact that babies are really sensitive to our communicative intent," Flom told TODAY Moms.
"They can really understand how we're saying something, so if you're talking to a young infant, they might not understand exactly what you're saying but they would certainly understand how it's being conveyed."
Researchers weren't too terribly surprised at the results. Studies have shown babies can match emotions in adults at 7 months of age and younger. But there has been little research so far looking into infants' perception of the emotional expressions of other infants.
Forty babies took part in the study: half were 3.5 months old, and the other 5 months old.
Image: Babies looking at each other, via Shutterstock