60秒科学:购物者,你可能低估了账单（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 [Koert van Ittersum, Joost M. E. Pennings and Brian Wansink] 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.

—Karen Hopkin

瞧，商店的收银员正扫描你的东西呢，当最后一个西红柿装进你的袋子时，有没有被总价格吓到啊？怎么花了这么多钱啊？没准是因为这些樱桃要12美元一磅。或者你应该注意一下都往推车里扔了些什么。又或者，什么原因都不是。因为《市场学期刊》的一项最新研究表明，购物时越是想要约束自己的花销，事实上会花的越多。

由于经济仍处于低谷期，坚持做预算是关键。食物是最大的花销，所以很多购物者们在逛街的时候尽量使心里的小算盘与扔进手推车里的东西一致。科学家们采访了300名购物者，发现其中超过一半的购物者们心里想着缩紧花销，却连计算器都不带，更别说一支笔和一张纸了。问题在于做心算是件比较困难的事情。结果是，他们总低估了他们的总花销，以超支华丽丽的收尾。

科学家们说，有一个窍门，数数你的推车里的东西，然后乘上你估算每件物品的平均价格就可以啦。举个例子，买了9件东西每件2美元，你给20美元还会找回些零钱。虽然并不完全准确，但是它肯定能告诉你是不是可以排在购买12件物品甚至更少件数的收银通道里（注解：有的超市会为购买件数较少的顾客开辟专门的收银通道以提高效率）。