A new study has found that human being are often irrationally optimistic about their future, even when confronted with a far less hopeful reality.

The study, published in the journal Nature Neuroscience yesterday, revealed that humans are generally biased towards expecting positive outcomes in the future and blatantly ignoring information about negative probabilities when it is presented to them.

In order to try and understand the known ‘pervasive human trait’ of ‘unrealistic optimism’, Dr Tali Sharot and her team at University College London assembled 19 volunteers, who were asked to estimate the likelihood of 80 different negative scenarios happening to them.

Mostly, the subjects’ estimates were more positive than statistics show is likely. Even more notably, when participants were presented with these gloomier statistics, they rarely altered their original estimates downwards.

However when the statistical likelihood of bad outcomes was lesser than the participants expected, they were far more likely to alter their estimate to fit the brighter statistics.

“For example, if we learn that the probability of suffering from a certain disease is actually less than what we expected, we take that information and we update that belief of how likely we are to suffer a medical disease,” said Dr Sharot.

"But if we get negative information about the future, for example, everyone knows that divorce rates are about 50 per cent, we don't take that information as relevant to us and don't change or estimate on how likely we are to get divorced."

Sharot - who also authored ‘The Optimism Bias’ - said that the tendency for humans to be unrealistically optimistic was due to a ‘fault’ in the brain.

“The reason is that regions of the front of your brain are very good at tracking and coding for positive information about the future,” she said.

“When you get negative information about the future, the frontal lobes don't code that information as efficiently.”

The consequently bright vision of the future can cause people to take irrational risks or not take reasonable precautions.

“It can also mean that we are less likely to take precautionary action, such as practicing safe sex or saving up for retirement,” said Dr Sharot.

However, optimism can often have the opposite effect.

As Dr Sharot wrote in May, “We now know that underestimating the obstacles life has in store lowers stress and anxiety, leading to better health and well-being. This is one reason optimists recover faster from illnesses and live longer.”