NEW research shows that those who know the least about autism - but are the most over-confident in their knowledge - are most likely to be hostile to vaccination and put their trust in non-experts.

The US study sheds light on the persistence of anti-vaccination campaigns despite repeated failures to establish a scientific link between autism and the triple MMR (measles, mumps and rubella) vaccine.

Read more: Travellers urged to check vaccination status as European measles cases soar 

The controversy first took hold following the publication of a now discredited study in the Lancet in 1998, written by British gastroenterologist, Dr Andrew Wakefield.

Researchers at the University of Pennsylvania, Texas A & M University, and Utah Valley University surveyed 1,300 American adults.

Study participants were asked to take a quiz testing their knowledge about the causes of autism. They were also asked to assess their own knowledge and the knowledge of experts.

The survey results showed that more than a third of study participants (36%) believe they knew as much as, or more, than medical doctors and scientists about the causes of autism.

While many respondents indicated trust in experts, they also placed high levels of trust in non-experts and the role of non-experts in setting policy.

Read more: Hundreds of students given MMR vaccine amid Edinburgh Uni measles outbreak 

However, the survey also found that those with the fewest correct answers on the quiz about the possible causes of autism showed the highest levels of overconfidence in their own knowledge.

The study states: “moving from low to high levels of autism knowledge was associated with a 39% decrease in overconfidence.”

The phenomenon is known to social scientists as the 'Dunning-Kruger effect': where people who lack expertise fail to recognize their own lack of knowledge.

Matthew Motta, postdoctoral fellow at the Annenberg Public Policy Centre at the University of Pennsylvania, said: “One reason for Dunning-Kruger effects is that people don’t know what they don’t know.

"Another reason may be that people are misinformed, believing something that the experts recognise as being untrue.”

Read more: University trials 'fake news vaccine' to combat spread of misinformation 

The study, published today, has been selected for an Atlas award. The plaudit recognises research which can significantly impact people's lives around the world.

Dr Motta’s team went on to show that this overconfidence has consequences when it comes to policy attitudes: those with the least amount of knowledge about autism and the most overconfidence were also less likely to support pro-vaccine policies.

They were also more likely to place greater importance on the role of non-experts in setting such policies.

The study has been published in the journal 'Social Science & Medicine'.

Cases of measles are on the rise in Europe. More than 41,000 case were recorded between January and June 2018, compared to 24,000 in 2017 - itself the highest count for any year over the previous decade.

The upsurge was blamed on a decline in MMR uptake.