DEAR MISS MANNERS: I’m not well-off, and my friend is. She loves eating at nice restaurants. I can’t afford those, so I usually take her out for hamburgers. She knows my financial circumstances. I am ...

Reciprocity (give-and-take exchange) is essential for successful human interactions. Feeling motivated to return a favor (and feeling owed for a favor) drives social behavior, personal interaction, ...

President Trump on Friday threatened to “reciprocate” travel warnings issued against the U.S. following a pair of mass shootings. Asked about his reactions to the travel advisories, Trump replied, ...