On one level, the research that emerged from HP Labs Friday is unsurprising: we tend to bow to peer pressure, and it's as true in social media as in real life.

But how much peer pressure does it take, and what other factors come into play? The answers may surprise you.

HP Labs computers scientists, including veteran online behavior researcher Bernardo Huberman, asked 600 participants to answer a few simple questions about online photos. Which of two baby pictures is cuter, and which of these two couches (above) would you choose to buy for a friend?

Whichever one they chose, the researchers rigged it so the other picture was shown to be more popular, using a Facebook-style Like system. The participants then had a chance to change their minds. Each time, however, they changed the number of Likes each picture got, and waited for a different length of time before giving them a second chance.

The result: 22% of people were swayed by the peer pressure — but only if there was a long gap between the first and second chance. Given the chance to change their mind immediately, only 14% of participants did so.

Most interestingly, people were only likely to change their minds if there were a moderate number of Likes on the other side. As soon as the Likes on their choice of picture were outweighed by 20 times or more, participants dug in their heels and stuck with their original choice.

Translation: if there's a large number of people who disagree with us, we're stubborn as hell. If you want to persuade someone to change teams, make sure their side does not appear to be outrageously unpopular, crushed by a giant weight of evidence. That, as I'm sure you're thinking too, could explain a whole lot about politics.

Huberman's advice for marketers? "Rather than overwhelming consumers with strident messages about an alternative product or service, in social media, gentle reporting of a few people having chosen that product or service can be more persuasive.”

Check out the full study, in PDF format, here.