Strength of conviction won’t help to persuade when people disagree

If you disagree with someone, it might not make any difference how certain they say they are, as during disagreement your brain's sensitivity to the strength of people's beliefs is reduced, finds a study led by UCL and City, University of London. The brain scanning study, published , reveals a new type of confirmation bias that can make it very difficult to alter people's opinions. "We found that when people disagree, their brains fail to encode the quality of the other person's opinion, giving them less reason to change their mind," said the study's senior author, Professor Tali Sharot (UCL Psychology & Language Sciences). For the study, the researchers asked 42 participants, split into pairs, to estimate house prices. They each wagered on whether the asking price would be more or less than a set amount, depending on how confident they were. Next, each lay in an MRI scanner with the two scanners divided by a glass wall. On their screens they were shown the properties again, reminded of their own judgements, then shown their partner's assessment and wagers, and finally were asked to submit a final wager.