By Jonny Lupsha, News Writer

After a killer shot two people during a live news broadcast in 2015, he uploaded his video of the attack to YouTube. The Washington Post reported that the graphic video is still viewable. The father of journalist Alison Parker has pleaded for the video to be removed; yet, it and countless violent videos remain on the website. How does content go viral?

According to the The Washington Post article, on August 26, 2015, journalist Alison Parker and her videographer were shot to death by a disgruntled former colleague during a live news broadcast in Smith Mountain Lake, Virginia. The killer filmed the double murder on a body-mounted camera. He then returned home and uploaded the video to YouTube. It has remained online from one user’s account, or another, ever since.

Andy Parker, Alison’s father, has notified Google and YouTube that the video is still watchable. “There is no specific law prohibiting YouTube from hosting disturbing videos,” the article said. “So Parker filed a complaint Thursday with the Federal Trade Commission, arguing that YouTube violates its own terms of service by hosting content it claims is prohibited.” In the most surprising twist of the entire story, YouTube claims to have removed “thousands of copies of the video of Parker’s shooting since 2015,” the article said. In other words, multiple YouTubers—people with YouTube accounts—have downloaded copies of the video independently and uploaded it to their own accounts in the last four years. The video has gone viral despite several removals of it.

Why YouTube Videos Go Viral

Dr. Jonah Berger, Associate Professor of Marketing at the Wharton School of the University of Pennsylvania, has spent 10 years studying word of mouth and why certain subjects catch on. After a decade of research, Dr. Berger developed an acronym called STEPPS—note the second P in “stepps”—that explains why things go viral.

“There’s a science behind why people talk and share,” he said. “In fact, six key factors kept coming up again and again. Whether we looked at products, ideas, news, or rumors, the same six things seemed to drive people to talk and share.”

Those six factors are Social currency, Triggers, Emotion, Public, Practical value, and Stories—STEPPS.

First is social currency. “Just like the car we drive and the clothes we wear, the things we say and the things we share affect how other people see us,” Dr. Berger said. “So one reason people talk about and share things is to get desired signals of identity.” This is social currency.

Second is the idea of a trigger. In our brains, a seemingly innocuous item can trigger a major memory for us, sometimes subconsciously. Dr. Berger said that people talk more about Cheerios than Disney World for the simple reason that we eat breakfast every day of the year, but don’t go to Disney World that often. Likewise, searches for the famously bad pop song “Friday” spike every Friday of the year.

Next is emotion, which is the simplest to understand. “When we care, we share,” Dr. Berger said. “The more we care about something, the more likely we are to pass it along.” Anyone who has advocated a cause or supported a local business has done this.

“The idea of public is, if something is easier to see, it’s easier to imitate,” Dr. Berger said. “This idea is based on a simple idea in psychology called social proof.” The public effect is that if you don’t know where to eat, you stop at a restaurant that’s full. Since it’s that full, the food must be good, right? Or if you see a shirt on a stranger that looks good, you may try to find that shirt to buy for yourself.

The fifth factor of ideas spreading is practical value, which is self-explanatory. “People share practical, useful information, or valuable information, to help others,” Dr. Berger said. With family and friends spread out so much farther now than 100 years ago, sharing useful information of value is done online or over the phone.

Finally, stories that intrigue us tend to spread like wildfire, and if they secretly contain some information, they’re doubly effective. Stories like this are “the idea that information travels under the guise of idle chatter,” Dr. Berger said. “If it’s built in a ‘Trojan horse’ or narrative, information will come along for the ride.”

Dr. Jonah Berger contributed to this article. Dr. Berger is an Associate Professor of Marketing at the Wharton School of the University of Pennsylvania. He holds a B.A. in Human Judgment and Decision Making from Stanford University and a Ph.D. from the Stanford Graduate School of Business.