Reciprocity
Also known as: Norm of reciprocity
We feel obligated to repay favors, gifts, and concessions in kind.
What it means
Reciprocity is the near-universal social rule that we should repay what others provide us, which creates a sense of indebtedness that motivates a return action. The obligation is powerful precisely because it is internalized and socially enforced — failing to reciprocate risks the label of ingrate — and it can be triggered even by an unsolicited or unwanted first favor, which is what makes it exploitable. Compliance professionals weaponize it with 'free' samples, gifts, and small concessions, because the recipient's felt debt often exceeds the value of what was given. A specialized form, reciprocal concessions, underlies the door-in-the-face technique: when a requester retreats from a large ask to a smaller one, the target feels pressure to match the 'concession' by agreeing. Reciprocity is also a cornerstone of cooperation more broadly, supporting trust, fair exchange, and the evolution of altruism among non-kin. It matters because it quietly governs gift-giving, sales, negotiation, fundraising, and everyday cooperation, and because awareness of an unwanted favor is the main defense against its pull.
Examples
A free sample, or an unexpected mint left with the bill, measurably increases purchases and tips by activating a sense of debt.
Charities tuck free address labels into appeal letters and donations rise — the unasked-for gift creates a small debt that recipients settle with a cheque worth far more.
A teenager asks to borrow the car for a fortnight, is refused, then asks for one evening. The retreat feels like a concession the parent is now pressed to match.
First described in Gouldner (1960); Cialdini (1984).