Most people want to give back to people who do something nice for them. In fact, social mores dictate that a favor should be returned in kind, and we apply pejoratives to those who do not: ingrates, moochers. In the second of a six-part series, psychology and marketing Professor Robert Cialdini talks about this phenomenon, which he calls &quot;reciprocity,&quot; and examines how the need to repay a kindness can be used to persuade others to agree -- or to work -- with us.<br><br><a href='http://knowledge.wpcarey.asu.edu/index.cfm?fa=viewArticle&amp;id=1341&#039; target='_blank'>http://knowledge.wpcarey.asu.edu/index.cfm?fa=viewArticle&amp;id=1341&lt;/a&gt;&lt;br&gt;&lt;br>