[header] How to use psychology to close more sales [title] Give something for free. [step] The principle of reciprocation is a psychological phenomenon described by dr. robert cialdini, an expert in persuasion. According to this theory, it is part of human nature to feel obligated to repay debts of all kinds, big and small. 
If someone receives something free, they will feel a psychological urge to purchase a product to pay you back for your kindness. [substeps] Offer a free trial period, a sample, or even a pleasant experience.