People with an optimistic outlook on life always seem able to look on the bright side of things. Turns out, they may literally be made that way. Scientists at the Wellcome Trust Centre for Neuroimaging at University College London published a study this week showing that the optimistic are different from the rest of us on a fundamental, neurological level.

The study shows that optimistic people tend to learn only from information that reinforces their sunny outlook. While it may be helpful in trying times, the trait is essentially due to "faulty" functioning in the frontal lobes of their brains.

"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," said Dr. Tali Sharot. "But it can also mean that we are less likely to take precautionary action, such as practising safe sex or saving for retirement. So why don't we learn from cautionary information?"

To find out, investigators examined the brain function of 19 volunteers using functional magnetic resonance imaging (fMRI), which shows changes in brain activity in real time.

The subjects were presented with a variety of negative life events, such as contracting diseases, or having a car stolen, and were asked to estimate the likelihood that such an event could happen to them. Later they were told the actual, statistical probability of such an event happening in a given person's lifetime.

After that the subjects were asked to re-estimate their own chances of suffering such setbacks. Subjects adjusted their estimates, but only in instances where the actual probabilities they'd been given were better than they had originally estimated.

If the actual probabilities were worse, they tended to ignore the information. Good news showed up on the brain scans as increased activity in the frontal cortex, but bad news tended not to elicit such activity in the brains of optimistic people.

"Our study suggests that we pick and choose the information that we listen to," said Dr. Sharot. "The more optimistic we are, the less likely we are to be influenced by negative information about the future. This can have benefits for our mental health, but there are obvious downsides. Many experts believe the financial crisis in 2008 was precipitated by analysts overestimating the performance of their assets even in the face of clear evidence to the contrary."