Here are 10 more ways consumers are bad at math, with an assist from historian and author William Poundstone.
(2) We're heavily influenced by the first number. You walk into a high-end store, let's say it's Hermès, and you see a $7,000 bag. "Haha, that's so stupid!" you tell your friend. "Seven grand for a bag!" Then you spot an awesome watch for $367. Compared to a Timex, that's wildly over-expensive. But compared to the $7,000 price tag you just put to memory, it's a steal. In this way, stores can massage or "anchor" your expectations for spending.
(3) We're terrified of extremes. We don't like feeling cheap, and we don't like feeling duped. Since we're not sure what things are worth, we shy away from prices that appear too high or too low. Stores can employ our bias for moderation against us. Here's a great story:
People were offered 2 kinds of beer: premium beer for $2.50 and bargain beer for $1.80. Around 80% chose the more expensive beer. Now a third beer was introduced, a super bargain beer for $1.60 in addition to the previous two. Now 80% bought the $1.80 beer and the rest $2.50 beer. Nobody bought the cheapest option.
Third time around, they removed the $1.60 beer and replaced with a super premium $3.40 beer. Most people chose the $2.50 beer, a small number $1.80 beer and around 10% opted for the most expensive $3.40 beer.
In short: We are all Goldilocks.
(4) We're in love with stories. In his book Priceless, William Poundstone explains what happened when Williams-Sonoma added a $429 breadmaker next to their $279 model: Sales of the cheaper model doubled even though practically nobody bought the $429 machine. Lesson: If you can't sell a product, try putting something nearly identical, but twice as expensive, next to it. It'll make the first product look like a gotta-have-it bargain. One explanation for why this tactic works is that people like stories or justifications. Since it's terribly hard to know the true value of things, we need narratives to explain our decisions to ourselves. Price differences give us a story and a motive: The $279 breadmaker was, like, 40 percent cheaper than the other model -- we got a great deal! Good story.
(5) We do what we're told. Behavioral economists love experimenting in schools, where they've found that shining a light on fruit and placing a salad bar in the way of the candy makes kids eat more fruit and salad. But adults are equally susceptible to these simple games. Savvy restaurants, for example, design their menus to draw our eyes to the most profitable items by things as simple as pictures and boxes. Good rule of thumb: If you see a course on the menu that's highlighted, boxed, illustrated, or paired with a really expensive item, it's probably a high-margin product that the restaurant hopes you'll see and consider.