Humans have an innate desire to be liked by peers and to feel a sense of belonging — and nowhere is this more prevalent than social media. The more likes, comments, and shares a post gets, the more socially validated the poster feels.

In fact, studies show that just these online reactions release dopamine in our brains, which makes us feel happy. Like gamblers at a slot machine, we anticipate a certain response when posting something online: Who will like my...