Specific Number Bias

​Read online​

---

I stumbled across this Reddit post a few weeks back.

Rather than listing the exact measurement of 29,000, the British Royal Geographical Society declared Mount Everest's elevation at 29,002.

Clearly, the surveyors thought that rounded numbers seem less believable.

Something that numerous studies have since proven.

Can You Spare 17 Cents?

In 1994, Santos, Leve and Pratkanis asked three female actors to approach 289 adults¹.

Each actor was instructed to ask the passersby for change. But there was a twist.

Half asked:

"Can you spare 17¢?"

The other half asked:

"Can you spare a quarter?"

The researchers wanted to know if asking for a specific number boosts donations.

It worked; the specific number made people 39% more likely to donate than the general request. It also led to a higher donation total (despite the actors asking for less).

19 years later, 5 different researchers tested the effect again.

Can You Spare 37 Seconds?

The 1994 study proved specific numbers worked with money, but would it work with time?

In 2015, Guéguen and his colleagues headed to the streets of Brittany in France².

For this experiment, they recruited four female actors dressed identically all in black to ask passersby to complete a survey.

300 passersby were asked (150 men and 150 women).

However, 150 were asked:

"I wonder if you have a little time to spare to answer a survey."

The other 150 were asked

"I wonder if you have 37 seconds to spare to answer a survey."

Of the 150 asked to spare a little time, only 63 agreed

Of the 150 asked to spare 37 seconds, 90 agreed.

A specific request boosted compliance by 42.9%.

Rounded numbers seem less believable. Specific numbers appear trustworthy.

So, when someone asks for 17 cents, we think, they must have a good reason.

When someone asks for 37 seconds, we think, this really won't take long.

And when Everest is measured at 29,002, we think that must be right!

---

The specific number bias is one of 85 principles you'll find in the Nudge Vaults.​

In fact, inside the Nudge Vaults you'll find 12 more insights specifically about this bias.

Get access to all 529 insights* right now →​

Or you can preview your first 50 insights for free →

Cheers,

​Phill​