© cathyse97 via Flickr Eternal Optimists - It'll definitely happen, Cubs fans. Someday.

Pervasive, persistent optimism is one of those uniquely human traits/flaws - we tend to believe things are better than they really are, or that negative consequences won't befall us, even if they befall others. It stands to reason that people would adjust their expectations when confronted with harsh reality, yet they don't. Our brains are to blame, according to a new study - we're wired to have a positive outlook.

Neuroscientists have been searching for the physiological underpinnings for this sanguineness, because there are actual harms that can come from an "it-can't-happen-to-me" or "it'll-get-better-this-year" attitude. People might make reckless decisions or have unrealistic expectations, in everything from personal health to finance. Researchers have thought this rose-colored outlook is mediated in the brain centers involved in error processing, so a team from England and Germany set about studying this using functional magnetic resonance imaging.

To study optimism, they examined how people under-estimated the impact or possibility of future negative events, because this "it-can't-happen-to-me" feeling has implications for how people protect themselves. The research team gave participants a list of 80 different negative life events, including getting Alzheimer's disease, being fired, being cheated on by a spouse, and so on. They were asked to rate how likely they were to experience these events, and then they were told their actual probability for experiencing the events. Then they were asked to estimate their own likelihoods of experience again. The scientists monitored brain activity during these tests.

People were far more likely to change their estimates when they learned they were less likely to experience these harms, according to the researchers, from the Wellcome Trust Centre for Neuroimaging at University College London, the Free University of Berlin and Humboldt University in Berlin. On the other hand, when things were worse than expected, the participants still gave the original, incorrect estimate.

Brain activity tracks with these findings, the researchers say. When things were better than expected, activity in the frontal cortices spiked, monitoring estimation errors. But when things were worse, the brain activity was much weaker.

"Our findings suggest that this human propensity toward optimism is facilitated by the brain's failure to code errors in estimation when those call for pessimistic updates," the authors write in the online version of Nature Neuroscience.

"Any advantage arising out of unrealistic optimism is likely to come at a cost. For example, an unrealistic assessment of financial risk is widely seen as contributing factor to the 2008 global economic collapse," they write. "Dismissing undesirable errors in estimation renders us peculiarly susceptible to view the future through rose-colored glasses."