Whether it's people thinking Hitler is actually alive and living in Argentina, or the classic "JFK was killed by the CIA" hypothesis, conspiracy theories are everywhere.

But what makes people believe in them, rather than the truths that Hitler definitely died in 1945 and JFK was killed by Lee Harvey Oswald acting alone?

A new study from the Zurich Institute of Public Affairs Research suggests it's all down to how much you misunderstand probabilities, hate uncertainty, and want to find an explanation for unlikely events.

The study, published in Applied Cognitive Psychology, involved a total of 2,254 participants and five experiments. In one of these experiments, the volunteers were asked to read fictional news stories involving a journalist having a heart attack. In different versions, they were told that his doctor had suggested he either had a 1 percent, 25 percent, 50 percent, 75 percent, or 95 percent chance of having a heart attack, PsyPost reports. They were then asked to rate how likely it was that the journalist had had a heart attack, or had been murdered.

When the fictional news report stated that a heart attack was unlikely, the participants were more likely to believe that the journalist was a victim of murder. In a second experiment, they were told that the journalist had recently reported on government corruption. In this scenario, even more participants believed that he had been murdered.

"The lower the probability of an event, the stronger participants embrace conspiratorial explanations," the authors wrote in their study.

"Conspiratorial thinking, we conclude, potentially represents a cognitive heuristic: A coping mechanism for uncertainty."

The research could explain conspiracies around deaths of public figures, such as the John F Kennedy assassination, where a lone gunman was able to kill a sitting president from an improbable distance.

"The results suggest that high-impact scenarios as well as scenarios with clear ulterior motives induce stronger belief in conspiratorial explanations," the authors wrote.

"A number of cognitive biases are, in essence, errors in probabilistic thinking, and conspiratorial reasoning might represent just another such bias. For example, we know that humans tend to have a difficult time with handling low probability events, especially if the events in question have both low probability and high impact."

The authors stress that more work needs to be done to investigate the link further, though they're hopeful that it could be used to help debunk conspiracy theories in future.