By Mark Beardsley
In 1974 a sociologist at Brigham Young University with too much time on his hands conducted an experiment. He sent Christmas cards with hand-written notes and photos of his family to 600 total strangers, just to see what would happen.
To his surprise, not only did he get more than 200 replies, but many included heartfelt responses, hand-written letters and photos. Further, he continued to hear from many of the same people for years.
The account was reported on National Public Radio recently, related to what is called the “rule of reciprocation,” an unwritten rule of society that basically says when someone gives us something, most of us give something in return. Every human culture has a such a rule.