A quick scan of videos that have gone viral shows content ranging from pranks, to silly dances, to serious social commentary and even stirring speeches. With a bag that mixed, it’s hard to believe that anyone could pin down or predict what makes a viral hit.

What, after all, could “DancePonyDance” and Candidate Obama’s music video have in common? (Side note: in times of government shutdown madness, how strange is it to remember that bit of earnest political idealism?)

But, fear not, scientists have been hard at work cracking the viral video code, and according to the British Psychological Society’s Research Digest, they may just have done it. In a study that asked 256 participants to watch ten videos, the team confirmed what you probably already suspected -- hitting the right emotional buttons is key:

According to a new study, the likelihood of someone choosing to forward a video depends on the emotion provoked by that clip.  Based on their findings Rosanna Guadagno and her colleagues describe what they call an "arousal hierarchy" - videos eliciting positive emotion, including joy and humour, are most likely to be forwarded; videos eliciting feelings of alertness and attentiveness are the next most likely to be forwarded. Clips that evoke negative arousal are near the bottom of the hierarchy, but still more likely to be forwarded than dull, non-emotional videos.

But let’s be honest, if you’re a business owner hoping to create the next million-hit-plus video, these results are somewhat helpful, but hardly likely to blow your mind. As BPS puts it, while “it seems joy and humour are sure-fire ways to give a video viral potential… there's no guaranteed recipe here for how to make a viral video. Had the researchers uncovered such a thing, they'd presumably be millionaires by now, or YouTube celebs at least.”  

So if capturing the right sort of emotion is necessary but not sufficient, what’s the missing part of the equation. How about sweat? Karen X. Cheng, a designer and serious dance enthusiast, saw her time lapse video of learning to dance go viral with millions of hits -- without debuting at the Super Bowl or otherwise receiving a expensive push from some big brand. But rather than simply cashing in on that success, she kindly pulled back the curtain in a revealing blog post entitled "How to Make Your Video Go Viral on YouTube."

It’s the sort of behind-the-scenes look at how the sausage gets made that we usually don’t get when it comes to viral videos, and Cheng is remarkably frank about all the hard work it took to launch a video that seemed -- to the untrained eye -- to simply take off on its own.

Among her other useful pieces of advice is "Don’t be ‘too good’ for a marketing plan." Cheng, drinking her own champagne, explains how much just marketing went into her video. "First, I posted to Facebook/Twitter, and submitted it to social news sites like Reddit and Hacker News. I personally asked many of my friends to share it. I tweeted it at well-known dancers. I emailed bloggers who had covered other viral dance videos." And that’s just on the first day! Effort, in other words, is the undersung reason many videos take off.

Are your efforts at viral videos lacking emotion or effort?