SSS 2010-03-08（在线收听）

So, they’re scanning your items at the grocery store, and when the last tomato gets bagged you’re stunned at the cost. How did you spend so much? Maybe those cherries were 12 bucks a pound. Or maybe you should have paid more attention to what you put in the wagon. Then again, maybe not. Because a new study in the Journal of Marketing shows that the harder shoppers try to keep track of what they’re spending, the worse they actually do.

With the economy still in the dumps, sticking to a budget is key. And food’s a major expense. So a lot of shoppers try to keep a mental tally of what they toss into the cart as they go along. Scientists interviewed 300 shoppers, and found that more than half of them try to crunch the numbers without a calculator or even a pen and paper. The trouble is doing that math in your head is hard. As a result, they underestimate their total cost, and end up overspending.

One trick, the scientists say, is to count what’s in your cart and multiply by a guesstimate of the average cost of the items. So nine things at $2 a pop should give you change of a twenty. It’s not perfect, but it’ll also tell you whether you can get in the 12 items or less lane.