科学证据表明你是一个乐观或悲观的人也许在你出生时就已经注定了。各位多愁善感时常情绪低落的同学，就面对现实吧。'Happiness' gene helps you look on the bright side

Positive people may owe their optimism to a gene variant that helps them dwell on the good and ignore the bad.

That's the conclusion from a study examining people's subliminal preferences for happy, neutral, and threatening images.

Volunteers who had inherited two copies of the "long" variant of 5-HTTLPR – a gene that controls transport of the mood-affecting neurotransmitter serotonin – showed clear avoidance of negative images, such as fierce animals, and a clear preference for positive ones, such as puppies. People with this variant combination are dubbed "LL" carriers.

The effect wasn't seen in volunteers with at least one version of the "short" variant of the same gene – these people showed no strong preference whatever the content of the images.

Time lapse

In repeated tests, the 97 volunteers had less than a second to identify dots hidden in one or other of a pair of adjacent images. Each pair contained a neutral image alongside one that was either positive or negative.

The researchers found that LL volunteers took 18.3 milliseconds longer on average to spot the dots in a negative rather than neutral image, suggesting a subliminal aversion to bad images.

Conversely, they noticed the dots 23.5 milliseconds sooner in the positive images, such as cuddly puppies, than in the neutral ones, suggesting they were subliminally drawn to them. "It sounds very small, but in terms of attentional time, it's consistent," says team leader Elaine Fox of the University of Essex in Colchester, UK.

Optimistic streak

Fox and her colleagues conclude that the LL volunteers may be primed to seek out positive events and ignore negative events.

Earlier studies had revealed a tendency for negativity and anxiety among individuals with at least one short variant of the gene, but the study is the first to reveal an optimistic streak in LL individuals.

"A number of mechanisms may contribute to this difference, and the authors have provided good evidence that attentional bias in the processing of emotional stimuli may be one of those mechanisms," says Turhan Canli, who has studied the same phenomenon at Stony Brook University in New York.

乐观主义者之所以会乐观向上也许是因为拥有能帮助他们凡事都向好的方面看且不去在意负面影响的基因。

通过一个检测人在看到愉悦、中立和具威胁性的图像时潜意识趋向性的实验，人们得出了以上结论。

5-HTTLPR基因能够控制影响人情绪的神经递质血清素的传递。拥有两对“长”变异5-HTTLPR基因的志愿者表现出对负面图像的明显排斥，如看到凶恶的动物，和对正面图像的明显喜爱，如看到小狗。带有这种变异基因组合的人被称为“LL”携带者。

在遗传了至少一条“短”变异5-HTTLPR基因的志愿者中则看不到这种趋向性。这些人对不同图片并没有明显的喜好。

时间差

在重复实验中，97名志愿者需在不超过一秒的时间里分辨出隐藏在一对相邻图像中任意一张里的黑点。每一对图像都包括一张中立的和一张或正面或负面的图像。

研究发现，携带LL基因的志愿者找出负面图像中的黑点比找出中立图像中的黑点用时长18.3毫秒，表明这部分志愿者潜意识里不喜欢看负面的图像。

相反地，这些志愿者找出正面图像，如可爱的小狗，中的黑点比找出中立图像中的黑点用时短23.5毫秒，表明他们潜意识里被正面图像吸引。“看上去是很小的差别，但说到集中注意力的时间，这个研究结果是前后一致的。”英国Colchester埃塞克斯大学的研究小组组长Elaine Fox如是说。

乐观的个性

Fox和她的同事们认为携带LL基因的志愿者也许天生就为寻找积极向上的事情，忽略有负面影响的事件做好准备了。

早先有研究表明拥有至少一条短变异5-HTTLPR基因的人个性有消极和抑郁的趋势，不过这次的研究第一次揭示了乐观个性和LL基因携带者之间的关系。

纽约Stony Brook大学的Turhan Canli，一位同样研究这一现象的学者，说道“有许多运行机制都可能造成这种人个性上的差异，作者为我们提供了良好的证据来说明在处理情绪刺激时的注意力偏向性也许是其中一种运行机制。”