Now researchers believe they have discovered, for the first time, why humans have a false sense of optimism。

　　Computer led simulations have shown that overconfidence in all aspects of life can often improve your chances of winning。

　　For many years scientists have been divided over whether overconfidence is a good or bad thing and why it existed。

　　‘There hasn't been a good explanation for why we are overconfident, and this new model offers a kind of evolutionary logic for that. It's unlikely to be an accident—we're perhaps overconfident for a good reason,’ said Dr Dominic Johnson of the University of Edinburgh。

　　Sprinter Usain Bolt is famed for his relaxed and confident approach to performing, as was ‘the greatest’ boxer Muhammad Ali。

　　But there is a word of warning for anyone thinks they could be faster than a speeding bullet, more powerful than a locomotive, or able to leap tall buildings in a single bound。

　　Positive self-delusion can also cause problems and lead to wrong decision making, unrealistic expectations, danger and failure。

　　他们经常因为太过自信甚至自负而遭到指责，然而成就最高的人往往是那些过高估计自身能力的人。

　　研究人员认为他们现在已经首度发现为什么人类会有过度乐观的心理。

　　电脑操纵的模拟实验显示，在生活中各个方面，过分自信经常能够增加获胜的几率。

　　多年以来，科学家对于过分自信是好事还是坏事以及为何会有这种心理一直存在分歧。

　　爱丁堡大学的多米尼克?强森博士说：“一直以来人们都无法较好地解释为什么我们会过度自信，这一新模拟实验为其提供了一种进化上的理由。这种心理不大可能是意外，我们会过度自信，或许是有合理的原因的。”

　　短跑运动员尤塞恩?博尔特以其放松而自信的比赛状态著称，“最伟大的”拳击手穆罕默德?阿里也是这样。

　　不过，研究人员也要警告那些认为自己可以比高速飞行的子弹还快，比机车还有力量，或能一跳就越过高楼的人。

　　积极的自我欺骗也会导致问题，并可能使人做出错误的决策、产生不切实际的期望、引发危险和造成失败。