1. A went to buy cigarettes, which cost 29 yuan, but he had no matches, so he told the clerk, “Send a box of matches by the way.” The clerk didn’t give it.
B went to buy cigarettes, they were 29 yuan, he also did not have matches, and said to the clerk: “10 cents cheaper.” Finally, he uses the 10 cents to buy a box of matches.
This is the simplest psychological marginal effect. The first one: the shopkeeper thinks he is making money on one item and not on the other. The second: the shopkeeper thinks that both goods are making money, the money index is 2. Of course, the psychological tendency is the second. Similarly, this psychology is also expressed in the buy one get one free gimmick, customers think that there is one thing do not have to pay, it makes money, in fact, are psychological marginal effect at play.
Insight: change a way often can play an unexpected effect! Usually many things a different approach results in a different outcome. It is important to improve mental models and ways of thinking on the road of life.