Humans are hard-wired for optimism and think good things will happen to them in the future despite no evidence to support such expectations, according to a study by U.S. and British researchers.

People expect to live longer and be healthier than average, underestimate their likelihood of getting a divorce and overestimate their prospects of career success, psychologists and neurologists from New York University and University College in London wrote in the latest issue of the periodical Nature.

The optimism is wired into the brain, they wrote, which recalls past events in an effort to imagine the future. Certain portions of the brain — the amygdala and the rostral anterior cingulate cortex — showed increased activity in test subjects who had been asked to imagine future events. 

The researchers used magnetic resonance imaging to monitor subjects while they thought of future possible events, such as winning an award or the end of a relationship.

"When participants imagined positive future events relative to negative ones, enhanced activation was detected in the rostral anterior cingulate and amygdala, which are the same brain areas that seem to malfunction in depression," said lead author Tali Sharot, now a post-doctoral fellow at University College London.

More optimistic participants showed greater activity in the rostral anterior cingulate region when imagining future positive events, Sharot said.

The researchers found test subjects usually expected positive events to happen sooner than negative events, and generally imagined them with greater vividness.

"Our behavioural results suggest that while the past is constrained, the future is open to interpretation, allowing people to distance themselves from possible negative events and move closer toward positive ones," NYU professor Elizabeth Phelps said in a release.

"Understanding optimism is critical as optimism has been related to physical and mental health. On the other hand, a pessimistic view is correlated with severity of depression symptoms."