Before the likes of Twitter and Facebook, an angry customer was just an annoyed guy complaining to his family and friends. Sure, that was bad for your business (particularly if it’s based in a small town or serves a tight knit community), but it’s nothing like our post-social media reality.

Now, one angry rant or enthusiastic shout out on social media can end up in front of thousands in no time. So as a business owner you’re no doubt hoping that the vast majority of what spreads about you online is positive.

Unfortunately, a new study suggests this hope may be swimming against the currents of human psychology.

The study was done by Rui Fang and a team of researchers at Beihang University in China and reported recently in the MIT Technology Review. The Chinese team analyzed 70 million tweets from 200,000 users on the Twitter-like Chinese site Weibo, looking to see how specific emotions spread through the network. What they found surprised the researchers. Some emotions, it seems, are far more catching than others, the Review reports:

They studied the way sentiments spread through the network. For example, if one person sent an angry tweet, how likely was it that a recipient would also send an angry message, and how likely was it that the recipient of this message would pass on the same sentiment and so on?

The results were something of a surprise. When it comes to sadness and disgust, Rui and co found very little correlation between users. Sadness and disgust do not easily spread through the network in this way. They found a higher correlation among users who tweeted joyful messages.

But the highest correlation by far was among angry users.

This suggests a less than pleasant conclusion for entrepreneurs -- happy comments about your product or service are likely to sink like a stone while complaints may skip along covering great social distances. But before you despair, be aware that there are several question marks hanging over the study.

One, it was done in China. While there’s no specific reason to think Americans would behave any differently than the study subjects, it is a possibility that we’re less easy to anger (yeah, I don’t think so either) or other social networks show different patterns.

The second caveat offers more hope for US entrepreneurs. Most highly shared angry messages were directed at domestic social problems and foreign governments. Politics, in short, really got people worked up. Bad service at the local bakery or with a bank’s customer service line, were less likely to go viral. That may suggest that businesses have a hard time causing the level of annoyance required for a highly contagious tweet, but the ultimate conclusion may be beware the consequences if you do manage to get anyone that riled up.

Do these findings jive with your personal experience of social media?