A mix of psychological disturbance fuelled by the “American Dream” and easy gun access has meant almost a third of all the fatal mass shootings since the 1960s have occurred in the US.
Experts who surveyed 171 countries found a link between levels of private gun ownership and the likelihood of an individual causing carnage with a firearm.
They also blamed the emphasis placed on success in the American society for the high proportion of mass shooters in the US, which is home to just five per cent of the world’s population.
The research correlated gun ownership and mass shooting incidents involving the deaths of four or more people between 1966 and 2012.
Dr Adam Lankford, an associate professor of criminal justice at the University of Alabama, said his study showed that a nation’s firearm ownership rate was the “strongest predictor” of its number of mass shooters.
“Until now, everyone was simply speculating about the relationship between firearms and public mass shootings,” he said. “My study provides empirical evidence of a positive association between the two.”
He added: “In the United States, where many individuals are socialised to assume that they will reach great levels of success and achieve the American Dream, there may be particularly high levels of strain among those who encounter blocked goals or have negative social interactions with their peers, co-workers, or bosses.
“When we add depression, schizophrenia, paranoia, or narcissism into the mix, this could explain why the US has such a disproportionate number of public mass shooters.”
The right to bear arms is written into the US constitution under the second amendment of the bill of rights.
President Barack Obama has pushed for stricter gun controls but has been frustrated by the pro-gun lobby, led by the National Rifle Association, which has many friends in Congress.
About 300 million firearms are estimated to be in the hands of civilians in the US. In 2011 a Gallup survey found 47 per cent of American adults reported keeping a gun in their home.
Dr Lankford said the US, Yemen, Switzerland, Finland and Serbia were the five countries in the world with the most private firearms per head of population.
“All five are ranked in the top 15 countries in public mass shooters per capital,” he pointed out. “That is not a coincidence.”
The study excluded domestic incidents or shootings that were primarily gang-related or involved hostage-taking or robberies .
It found that mass shooters in the US were 3.6 times more likely to have used multiple weapons than those in other countries.
The Mass Shooting Tracker, an online database run by gun opponents in the US, has listed 231 American mass shootings – involving four or more people shot – over the past year up to August 10.