An expert breaks down the psychology behind the copy-cat threats that followed the recent mass shootings at Walmart

• A number of Walmarts across the United States have received threats since the El Paso shooting earlier this month. 
• These incidents have prompted police investigations and, in some cases, arrests.
• Business Insider spoke to psychologist, Temple University professor, and former president of the American Psychological Association about the recent string of threats.
• He told Business Insider that many threat-makers, regardless of whether or not they intend to carry out their threats, may share certain motivations with mass shooters.
• Visit BusinessInsider.com for more stories.

Walmart stores across the country have faced a stream of threats in the wake of the deadly shooting in an El Paso supercenter that left 22 people dead and 24 more injured.

The spotlight has remained on Walmart since that August 3 shooting, leading to an employee walk-out, controversy over the company's decision to continue selling firearms, and several highly-publicized store incidents, including a number that led to store evacuations and police investigations.

Some of those instances were later confirmed to stem out of misunderstandings. But other incidents involved people threatening to commit mass murder within various Walmarts across the country. Walmart did not respond to Business Insider's request for comment. 

An ABC affiliate in Texas reported that an as-of-yet-unidentified masked man incited a stampede in a Houston mall after he allegedly jumped on a table and claimed that he was going to shoot himself. In the panic that ensued, police also received calls reporting shots fired in a nearby Walmart.

An unnamed 13-year-old was also arrested on suspicion of making threats against a local Walmart on Instagram, CBS Austin reported

In Florida, the FBI and local police arrested 26-year-old Richard Clayton, an alleged white supremacist who is accused of threatening to attack Walmart with an AR-15, according to local channel My News 13.

Authorities are also investigating an anonymous Reddit user, who wrote on the website that he planned to commit the "biggest mass shooting in modern American history" in either Kansas or Missouri.

According to CNN, as of yesterday, eight Walmarts have received threats over the past few days. At this point, it's unclear whether any of the threats that followed the El Paso shooting were viable. Nonetheless, these incidents have still managed to strike fear into communities.

Violent threats against Arkansas-based retailer predate the El Paso mass shooting. Walmart stores were targeted with bomb threats in Texas, Wyoming, and Florida over the past year. But the deadly and recent El Paso shooting has seemingly elevated the amount of scrutiny that such threats receive from authorities, the media, and the public.

Frank Farley, a psychologist and professor of psychological studies in education at Temple University, spoke to Business Insider about the spate of threats against Walmart.

When considering a threat-maker's motives, Farley stressed that's important to remember that "no human behavior is due to just one thing"; it's more helpful to think of them as "recipes with a few ingredients." He also noted that more research is desperately needed on the psychological factors of mass shootings.

But when it comes to the thought process of a person calling in threats to a retail store, Farley said that such individuals might share several motivations with mass shooters themselves: namely a desire for thrills, a wish to spark fear and panic, and a hunger for fame.

Read more: In response to office violence, companies have begun holding active shooter drills - but they can do more harm than good

"A primary source of human fear is uncertainty," Farley told Business Insider. "If you make the threat, even if you have no intent of following through on it, it will still raise the fear level."

He said that people who threaten mass violence, regardless of whether or not their threats are idle, may also be seeking attention.

"Most of us go through life without much fame," he said. "We're pretty much all unknown and our lives are fairly humdrum. If we taped our lives, many of us aren't going to win the Oscar."

He explained that threatening a Walmart in the wake of a highly-visible mass shooting could be viewed as "an opportunistic behavior, where you see a chance to instill some fear and panic, and make a public impact of some sort."

And the recent string of threats are likely tied to the El Paso shooting in an even more direct way. Farley said that mass casualty events can trigger fear-of-missing-out, or FOMO, in like-minded individuals.

"Maybe you've had these thoughts about doing some horrendous," Farley said. "You didn't do it, and somebody else has done it."

Therefore, many people calling in or posting threats against Walmart, according to Farley, may be trying to "get in on the act."

Email tips to acain@businessinsider.com.