your brain won’t allow you to believe the apocalypse could actually happen

io9 | You may love stories about the end of the world, but that's probably because, deep down, you don't believe it could ever happen. But that's not because you're realistic. It's actually a quirk of the human brain, recently explored by a group of neuroscientists, which prevents us from adjusting our expectations about the future — even if there's good evidence that bad things are about to happen.

A group of researchers from Germany and the UK designed a fairly complex psychological test to determine how people planned for negative events in the future. First, they asked the about the likelihood of 80 different disturbing events happening, such as contracting a fatal disease or being attacked. After they'd recorded people's responses, researchers told each subject the actual, statistical likelihood of such events happening. In some cases, people had overestimated the likelihood and in some cases they'd underestimated it.

Then, after some time had passed, the researchers asked subjects again about the likelihood of these events happening to them. Interestingly, they found that people had a much harder time adjusting their expectations if the real-world statistical likelihood was higher than what they had first guessed. They had little trouble adjusting expectations for a more favorable outcome. It was as if people were selectively remembering the likelihoods of future events — forgetting the bad odds but not the good ones.

And in fact, that's exactly what was happening. The researchers had been doing fMRIs on the people when they did these tests, and were able to see which areas of the brain became active when people remembered (or failed to remember) how likely it was that they would face a horrible calamity. In their paper, published this week in Nature Neuroscience, the researchers write:

We found that optimism was related to diminished coding of undesirable information about the future in a region of the frontal cortex (right IFG) that has been identified as being sensitive to negative estimation errors . . . this human propensity toward optimism is facilitated by the brain's failure to code errors in estimation when those call for pessimistic updates. This failure results in selective updating, which supports unrealistic optimism that is resistant to change.

Basically, human optimism is a neurological bug that prevents us from remembering undesirable information about our odds of dying or being hurt. And that's why nobody ever believes the apocalypse is going to happen to them.

There is one fascinating exception to this rule, though. As the researchers note, the only people who consistently offer accurate estimates of bad things happening to them are clinically depressed. So — perfect depression is perfect awareness?

Ultimately our neurological bugginess could serve an adaptive function, which is preventing us from becoming so depressed about the impending apocalypse that we can't get out of bed in the morning.