reciprocity (Cialdini) termbias
people feel obligated to return favors, even unwanted ones
Cialdini's first principle of influence: doing something for someone creates a felt obligation to return the favor. Even tiny, unrequested gifts (mints with the bill, free samples) measurably change behavior. In negotiation: a small concession invites one back. In sales: free trials anchor people toward purchase. Easy to weaponize, hard to defend against in real time.