James Rilling of Emory University in Atlanta published the study in The Royal Society in November, 2021. His team surveyed 50 grandmothers each with one biological grandchild between 3 and 12 years old and one of their own child. They also measured the brain function as the participants viewed pictures of their grandchild and the same-sex parent of the grandchild. Researchers found that grandmothers viewing their grandchild's pictures activated parts of the brain that involved emotional empathy (共鸣) and movement.

In contrast, the study also found that when grandmothers viewed images of their adult child, they showed stronger activation in an area of the brain associated with cognitive (认知的) empathy. That indicates they may be trying to cognitively understand what their adult child is thinking or feeling and why, but not as much from the emotional side. Compared, with results from an earlier study by the Rilling lab of fathers viewing photos of their children, results showed that grandmothers activated more parts of the brain that involved emotional empathy and motivation.

"That suggests that grandmothers tend, to feel what their grandchildren are feeling when they interact with them," Rilling said. "If their grandchild is smiling, they're feeling the child's joy. And if their grandchild is crying, they're feeling the child's pain and sorrow." In many societies, grandmothers are important caregivers, and their investment is often, associated with improving their grandchildren's well-being.

It's part of the reason why the US celebrates Grandparents'Day each year on the first Sunday after Labor Day in September. The announcement was signed in 1978. "Because grandparents are usually free to love, guide and befriend the young without having to take the daily responsibility for them, they can reach out past pride and fear of failure, and close the space between generations," the announcement read.