The phenomenon of 'unrealistic optimism' is a common human trait. A new functional MRI study, led by Raymond Dolan from University College London, UK, shows that extreme optimists have a reduced ability to adjust their predictions when they receive negative information that challenges their beliefs — an effect mediated by the right inferior prefrontal gyrus of the prefrontal cortex.

“Seeing the glass as half-full rather than half-empty can be a positive thing — it can lower stress and anxiety and be good for our health and well-being,” explains Tali Sharot, joint first author of the new paper ( Wellcome Trust News , 10 Oct 2011). “But it can also mean that we are less likely to take precautionary action, such as practising safe sex or saving for retirement,” she adds ( Daily Mirror News , 10 Oct 2011).

Read Montague, Director of the Computational Psychiatry Unit and Human Neuroimaging Lab at the Virginia Tech Carilion Research Institute, USA, thinks that selecting for positive information might allow animals to learn how to rapidly obtain food ( Science News , 13 Oct 2011). “The fact that the brain is not showing this computation is because it's adaptive at the end of the day,” says Sharot (Science News).

The broader implications of the study are highlighted by John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, UK, and Chris Chambers from the University of Cardiff, UK. “Understanding how some people always manage to remain optimistic could provide useful insights into what happens when our brains do not function properly,” comments Williams (Wellcome Trust News). Chambers adds: “this work highlights ... that a major part of brain function in decision-making is the testing of predictions against reality — in essence all people are 'scientists'” ( BBC News , 9 Oct 2011).