Researchers used electroencephalogram technology to study the brain activity of the two when the mother sang nursery rhymes to the baby  They found that when the mother and the baby looked at each other, the brain waves of both sides tended to be synchronized  Mother communication
The brain waves tend to be synchronized to optimize the dialogue between the two parties, make the communication more tacit, and enhance mutual understanding
 Based on this, they believe that looking at each other between the mother and the baby will help the baby's learning and communication