Learning to resist anchoring cues

The De Beers diamond cartel is sinisterly clever. Diamonds are by no means the rarest gemstones on earth, but by enforcing artificial scarcity, De Beers has been able to charge much more for diamonds than rarer stones. The cartel also came up with a campaign to make people believe that it's customary to spend an equivalent of two months' salary on an engagement ring. (For more about this, read this interview with Janine Roberts, author of Glitter & Greed: The Secret World of the Diamond Cartel and this Slate article about the history of engagement rings).

The technique of dangling a number in front of a consumer in a way that suggests it's the social standard is known as "anchoring." Author William Poundstone explains anchoring on his blog, Priceless, by offering the example of a supermarket that advertised 10 cans of salsa for $10. On closer inspection, the cans of salsa sold for $1 each, so there was no savings for buying ten at a time. But, explains Poundstone, "It's been shown that when people have to come up with a numerical estimate on intuitive grounds, they are easily swayed by any numbers provided as cues (or 'anchors')." So, with the number 10 offered as the social norm, people are more likely to buy at least a few cans of salsa rather than just one.

When it comes to buying diamonds, which most people won't do more than once or twice in their lives and have no idea what diamonds are really worth, people will grab any anchor given to them. And De Beers is only too happy to provide one: "two months' salary."

In his blog post, Poundstone has a great example of just how powerful anchoring's effect is on people. Researchers Karen Jacowitz and Daniel Kahneman presented the following two-part question to a group of subjects:

(a) Does the average American eat more or less than 50 pounds of meat a year?
(b) How much meat does the average American eat in a year?

The median answer to question (b) was 100 pounds. Next, the researchers asked another group of subjects the same two-part question, but this time, they asked whether the average American ate more or less than 1000 pounds of meat in a year. The median answer this time was 500 pounds of meat. In other words, the anchoring cue increased the median answer by 500 percent!

Poundstone offers no suggestions for learning how to resist anchoring cues. I suspect it's because it's impossible to completely ignore them. Psychologists have learned that being aware of manipulative tricks doesn't do much to diminish their efficacy, so what can be done to counteract anchoring cues? If you have the answer, please share it in the comments!

Mark Frauenfelder – Editor-in-chief of MAKE magazine and the founder of the popular Boing Boing weblog, Mark was an editor at Wired from 1993-1998 and is the founding editor of Wired Online.