背景：

得过彩票大奖吗？没有？那你还会再买吗？如果答案是“会”，那你或许就是个乐观的人。

伦敦大学的研究表明，人类是天性乐观的生物。

Ever won the lottery? No? But did that stop you buying another lottery ticket?

If the answer is another 'no', you might call yourself an optimist.

But then, according to researchers at University College London, human beings are naturally

sanguine

creatures.

It is all in the brain, they say. A study suggests it is very efficient at processing good news: about 80% of people have a tendency

to see the glass as half-full, not half-empty

, even if they don't consider themselves to be optimists.

The good news is that this brings a health benefit. Being upbeat and having a positive outlook on life reduces anxiety. A study of nearly 100,000 women showed a lower risk of death from heart disease amongst optimists.

But there are pitfalls to always having an

upbeat attitude

. The authors of the study point out the 2008 financial crisis may have been caused by analysts

overestimating

their assets' performance even

in the face of

clear evidence to the contrary.

There are personal health risks too. Dr Tali Sharot, lead researcher, said: "'Smoking Kills' messages don't work as people think their chances of cancer are low. There's a very fundamental