True or false? Giraffes are the only mammals that can't jump.

According to a growing body of evidence, there are factors pushing you to rate that claim as true — and they have nothing to do zoology, biology, or general knowledge.

It comes down to the fact the claim is presented alongside a generic photograph.

While the above information is false (giraffes can actually jump — it's elephants that can't), Australian National University researcher Dr Eryn Newman said people were more likely to believe it because it was presented alongside a photo.

On top of that, people who fall victim to it probably are not aware that it is affecting their decision making.

"What we've found across a number of different studies, maybe five or six years' worth of research, is that adding a photograph to a message, even when that photograph provides no evidence, actually systematically shapes people's beliefs," Dr Newman said.

Dr Eryn Newman (image included for believability). ( Supplied: Australian National University )

"Instead of turning to facts or general knowledge, we often go along with what feels right, or in other words an 'intuitive response'.

"[Photographs] increase the ease with which we can process information — they make information feel right."

Dr Newman said the addition of an image could favourably affect a person's evaluation of a claim 60 to 70 per cent of the time.

In several experiments, some dating back years, participants were asked to rate a claim as "true" or "false", including control claims presented without pictures.

"They might see claims like 'giraffes are the only mammals that can't jump', or 'magnesium is the metal that appears inside a thermometer'," Dr Newman said.

"And we're talking about photographs that really have no probative value, so the giraffe claim would be with a photograph of a face of a giraffe, which really doesn't tell you anything about whether they can jump."

Participants were more likely to believe both true and false claims if they were presented alongside a relevant picture.

But a large majority of participants claimed they were not influenced by the presence of an image, even when the data showed they were.

"People really don't have a good insight into whether they are being biased by the presence of a photo," Dr Newman said.

If it's easy to digest, we're more likely to believe it

Dr Newman has also looked at how audio quality, and even how easy someone's name is to pronounce, affect whether people rate information as true.

"Any variable that increases the ease with which people can process a message also increases the chances that people believe it," she said.

Sorry, this audio has expired Dr Newman has previously investigated the link between poor audio quality and how people evaluate facts.

And she said that had serious consequences to how we process information.

"The concern is that when a photograph is paired with a flashy headline that is about false information, it becomes particularly dangerous," she said.

"It actually increases the chances that the false information sticks.

"And what we know from social media is that sometimes people are actually sharing information without actually even reading the news articles, they see the headline, see the photograph, and then within a few seconds it's already on the news feed."

Even a generic image of a politician will enhance the believability of a claim about them. ( Reuters: Kevin Lamarque )

Dr Jason Tangen from the University of Queensland said our judgements and decisions were affected by a range of invisible — and seemingly unimportant factors.

"People are often surprised to learn that we have very little insight into how we actually make most of our everyday decisions," he said.

"It seems that we're largely oblivious to the determinants of our own behaviour, we misjudge how long tasks will take, we don't know what makes us happy or unhappy or the factors that affect our impression of a job candidate, and we're surprised to learn that a photo can influence our truth judgements.

"At first, this might seem like a trivial finding, but think about the implications for, say, how expert witnesses ought to present evidence in court where people's lives and livelihoods hang in the balance."

Dr Tangen said people were less likely to be influenced by non-probative factors if they already had background knowledge about an issue.

"The more you know about a particular area, the less likely you are to be swayed by irrelevant information," he said.

"So the best way to avoid traps like these is to know more! And there's been an enormous amount of research recently on the best ways to learn new skills, so there are plenty of resources out there to help you."

Dr Newman said more research was underway about how we can mitigate or override the factors that push us towards this kind of decision making.

"We're hoping to discover that by understanding the processing strategies that make people more vulnerable, we can sort of shift people into a more careful, analytical approach that might protect them from some of these effects," she said.