US Republican voters are less likely to be critical about the performance of the controversial “Obamacare” health reforms when they are reminded about their own medical needs, new research shows.

The changes, introduced by former President Barack Obama, are now at risk after new President Donald Trump promised to scrap the Affordable Care Act (Obamacare) in favour of his American Healthcare Act.

Encouraging those opposed to President Obama’s reforms to think about their health makes them less likely to judge it in a partisan way, according to a new survey by academics from the University of Exeter and Rutgers University. Making Republicans assess their own medical needs and giving them independent information about “Obamacare” makes them less likely to disagree with evidence about the former president’s healthcare reforms.

Researchers worked with an analytical sample of 661 US adults and divided them into two groups. During an online survey in January 2015 one group was primed to think in a partisan way by being asked a series of questions about their political beliefs. Another group were asked a series of questions about their own needs for and concerns about health and health care.

Both were then given real performance information about the Affordable Care Act and asked to process the information using two tasks – assessing the strength of evidence statements in a real performance report about the act and choosing the most useful performance information from a chart in the report.

The respondents who were asked to think politically viewed evidence in a more partisan way. Democrats selected evidence which gave the Affordable Care Act a large advantage compared to the information selected by Republicans. When primed to think about their own health both voters used the evidence in a more balanced way. The results shows those with strong political beliefs are likely to manipulate facts to reinforce their own attitudes, but also that factual evidence may have limited potential in enhancing democratic accountability.

Professor Oliver James, from the University of Exeter, who carried out the research, said: “We know that Democrats are more in favour of the Affordable Care Act than Republicans. Their views about evidence didn’t change when they thought politically while looking at impartial information. But it did change when they thought about facts in the context of their own health.

“Government and officials assume that giving the public impartial information about public services can help people make accurate judgements about how they are performing. This research shows that this is not the case, at least for services where there are substantial disputes along party political lines. Ultimately, more independent sources of evidence that are trusted across partisan lines may be the best hope for informing public debate in this and similar contexts.”

“Motivated Reasoning about Public Performance: An Experimental Study of How Citizens Judge the Affordable Care Act” by Oliver James from the University of Exeter and Gregg G. Van Ryzin from Rutgers University is published in the Journal of Public Administration Research And Theory.