Other tricks, such as this one documented in a study last year, are more subtle:
A salesperson can totally alter a window shopper's inclination to buy something by simply asking the right question. When a salesperson asks a shopper which of several items she prefers, the shopper tends to skip the whole "Should I buy it at all?" question and go straight to the "Which one should I buy?" phase. The study was done in simulated tests and in real-world retail situations.
“Stating a preference appears to induce a which-to-buy mindset, leading people to think about which of several products they would like to buy under the implicit assumption they have already decided to buy one of them,” wrote Alison Jing Xu and Robert S. Wyer, Jr. of the Hong Kong University of Science and Technology. “Consequently, they are more disposed to make a purchase than they otherwise would be.”