Reciprocity is when people comply out of feeling that they need to return a favour. If some one does something for you, you feel more obligated to return the favour. For example, Lynn and McCall (1998) found that restaurant diners leave a bigger tip when a mint or a sweet was offered with the bill. Regan (1971) did an experiment to test reciprocity. One participant and a confederate of the experimenter were asked to rate paintings. In the experimental condition, the participant received a bottle of Coca-Cola. The participant in the control condition did not receive anything. Participants were asked if they would buy tickets. Regan (1971) found that the participants in the experimental condition bought more tickets compared to the ones in the control condition. This experiment had a high-degree of control. There might be some issues of ecological validity as well as sample bias. But, the findings have been supported by observations in real life.
One compliance technique is the door-in-the-face technique. It is the situation when one makes a request which is turned down, because it is obviously too big. A smaller request is then made, which have a higher chance of being accepted, since the person whom the request is made to will