A 2014 study of 55 caregivers eating with young children in fast-food restaurants found the ones most absorbed in their phones responded more slowly to a child’s bids for attention, showing how a parent’s fading interest shows up before any words are said.

The millisecond a parent's attention fractures, children register the shift—and it can reshape how they learn to read other people's emotions. The post A 2014 study of 55 caregivers eating with young children in fast-food restaurants found the ones most absor…