People who falsely believe that a bogus drug works find it harder to accept the evidence that a truly effective medication is beneficial, a study by researchers at the University of Deusto in Spain and UNSW Australia shows.

The research, which is published in the British Journal of Psychology, could have implications for how people make medical decisions in real life, such as whether to get their children vaccinated.

The authors were interested in the possibility that promotion of ineffective, pseudoscientific therapies could make people less likely to believe that proven treatments work, which could make people reject the use of conventional medicine, sometimes with serious consequences.

Humans are prone to developing false beliefs, particularly about the causes of events – for example, often thinking that their own abilities determine success in tasks when the outcome is really just a matter of chance.

While false beliefs can have psychological benefits, such as giving people a sense of control over life, they are not without risk.

In the first phase of the study of 147 people, the researchers induced half of the participants to develop a strong false belief that a medication could effectively treat a fictitious disease.

They did this by showing all participants 100 scenarios where the drug was or wasn’t taken by a patient, and the patient did or didn’t get better.

The chance of recovery was the same, with or without the drug, but the 50 per cent of participants who were shown the drug more frequently developed a stronger belief that it was effective.

In the second phase of the study, participants were shown another 100 scenarios where the bogus drug was combined with one that did cause the fictitious patient to get better.

The main result of the study is that participants who held the strong false belief about the bogus drug had more difficulties learning that the added drug was effective.

The authors say a consequence of these results could be that people who live in an area or country where consumption of a pseudoscientific therapy for a disease is high can develop the false belief that the pseudoscientific therapy is effective. This illusion could interfere with the acquisition of evidence-based knowledge about the effectiveness of scientific medicine.

The study authors are Dr David Luque form the UNSW School of Psychology and the University of Málaga in Spain, and Dr Ion Yarritu and Professor Helena Matute from the University of Deusto in Bilbao.

Media contact: Deborah Smith: 9385 7307, 0478 492 060,