Marketing researchers have studied this expertise in a very specific way. They stop shoppers exiting a supermarket for a quick survey. They take the shoppers’ receipts and ask questions like, “How much was the Crest toothpaste you just bought?” Affluent shoppers do not do well on this quiz. “The price of the Crest toothpaste? Something like three dollars? Maybe five?” Most don’t even know how much they spent in total, the size of the bill they had just paid minutes before. But the lower-income shoppers do. They are more accurate in knowing both how much they spent and the prices of the items
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