A new study has found the strongest opponents to GM food think they know the most, but tend to know the least.

Marketing and psychology researchers asked over 2,000 US and European adults their opinions about GM foods.

Respondents were asked how well they thought they understood genetically-modified foods, then tested how much they actually knew.

Despite a scientific consensus that GM foods are safe for human consumption and have the potential to provide significant nutritional benefits, many people oppose their use.

More than 90 per cent of study respondents reported some level of opposition to GM foods.

The paper's key finding is that the more strongly people report being opposed to GM foods, the more knowledgeable they think they are on the topic, but the lower they score on an actual knowledge test.

“This result is perverse, but is consistent with previous research on the psychology of extremism,” said Professor Phil Fernbach.

“Extreme views often stem from people feeling they understand complex topics better than they do.”

A potential consequence of the phenomenon, according to the paper's authors, is that the people who know the least about important scientific issues may be likely to stay that way, because they may not seek out - or be open to - new knowledge.

“Our findings suggest that changing peoples' minds first requires them to appreciate what they don't know,” said study co-author Nicholas Light.

“Without this first step, educational interventions might not work very well to bring people in line with the scientific consensus.”

The paper's authors also explored other issues, like gene therapy and climate change denial. They found the same results for gene therapy.

However, the pattern did not emerge for climate change denial. The researchers hypothesise that the climate change debate has become so politically polarised that people's attitudes depend more on which group they affiliate with than how much they know about the issue.

The full study is accessible here.