9月30日：当鸟类向飞行中的蝴蝶发起攻击时，它们可能会看到一些并不存在的假象——蝴蝶翅膀的闪烁其实可能并非像看上去那样在移动。等到捕食者意识到这种错觉时，蝴蝶可能早已逃脱了。
Sept 30 : When a bird lunges at a butterfly in mid-flight, it may see something that is not there — the insect's wings flashing beneath may not be moving where they appear to be moving. By the time the predator realizes the illusion, the butterfly already may have escaped.
研究这种自然防御机制的科学家发现，蝴蝶翅膀上的不同图案与翅膀的摆动共同作用，会产生误导性的运动信号，使得捕食者更难以判断蝴蝶的飞行速度和方向。
Researchers studying this natural defence have found that contrasting wing patterns can work together with wing movements to create misleading motion signals, making it harder for predators to judge a butterfly's speed and direction during flight.
“蝴蝶翅膀上的图案与它们的翅膀摆动相结合，形成了视觉错觉，使蝴蝶看起来移动的方向与实际方向不同，”英国埃克塞特大学的乔利恩·特罗斯奇安科（Jolyon Troscianko）教授说。他是这项发表在《自然》杂志上的研究的负责人。“这种错觉足以让蝴蝶在鸟类试图捕捉它的那一瞬间幸免于难。”长期以来，科学家们就认为条纹和其他醒目的图案能够产生“视觉干扰”（即让捕食者难以判断蝴蝶的运动方向）。
"The patterns on butterfly wings combine with their wingbeats to create optical illusions, making it look like the butterfly is moving in a different direction to its actual course," said Jolyon Troscianko, a professor at the University of Exeter in England and a leader of the study published in the journal Nature. "This is likely enough to save a butterfly from the split-second moment when a bird would try to catch it." The idea that stripes and other bold markings can create "motion dazzle" has long been proposed by scientists. But experiments involving animals including zebras, snakes and lizards have produced mixed evidence, and many studies did not account for the movements of wings or limbs.
然而，针对斑马、蛇和蜥蜴等动物的实验得出的结果并不一致；许多研究也没有充分考虑蝴蝶翅膀或肢体的运动方式。
"Butterfly wings are flexible surfaces that clap together and fling apart, and also pivot forwards and backwards in a figure-of-eight as they fly.
“蝴蝶的翅膀非常灵活：在飞行过程中，它们会相互拍打、分开，并以‘8’字形前后摆动。这种运动方式使得前翅上的条纹在向下摆动时显得更加明显、更加缓慢，”特罗斯奇安科解释道。“但在向上摆动时，这些条纹会迅速折叠并沿着飞行方向扭转。因此，尽管蝴蝶实际上是在向上飞行，但其向下的运动轨迹反而更加容易被观察到。”
This movement means that a stripe across the forewings can be visibly and slowly moving down on the down-stroke," Troscianko said. "But on the up-stroke, this stripe is rapidly folded away and twisted in line with upwards flight direction. Together these make the downwards motion of the butterfly much more visible than its upwards motion, even though it is flying up," Troscianko added.
为了验证这一理论，研究人员结合了高速拍摄技术、计算机建模、模拟进化过程以及触摸屏实验来进行研究。
To investigate the idea, the researchers combined high-speed filming of real butterflies, computer modelling, simulated evolution and touchscreen experiments.
“条纹尤其擅长干扰探测运动的神经回路，”特罗西安科说。“理发店旋转灯柱错觉就是一个很好的例子——横向移动的条纹看起来像是在上下移动。”这些图案似乎还会增加攻击过程中对蝴蝶位置的不确定性。
"Stripes are particularly good at interfering with the circuits that detect motion," Troscianko said. "The barber pole illusion is a good example — stripes moving sideways can look like they're moving up or down instead." The patterns also appear to increase uncertainty about a butterfly's position during an attack.
“这种增强的‘迷惑’效果如果不进化出一套根本不同的视觉系统，几乎不可能被克服，”特罗西安科说，并暗示这可能对蝴蝶作为一个类群的成功起到了关键作用。然而，并非所有蝴蝶都使用这种策略。
"This increased 'confusion' effect would be almost impossible to overcome without evolving a fundamentally different visual system," Troscianko said, suggesting it may have been pivotal to the success of the butterflies as a group. Not all butterflies appear to use this strategy, however.
“最不会造成运动迷惑的蝴蝶通常是棕色或红色的，”特罗西安科说，并暗示一些物种可能更依赖伪装，或依赖警告色来向捕食者发出信号，表明这种昆虫有毒、有害或味道不佳。
"The least motion-confusing butterflies are typically brown or red," Troscianko said, suggesting that some species may rely more on camouflage or on warning colours that may signal to predators that the insect is toxic, poisonous or has a bad taste.
为了测试这些效果是否会影响攻击行为，研究人员招募了100名人类志愿者，并进行了3000次虚拟捕蝶实验。参与者观看视频，并尝试通过点击屏幕来捕捉蝴蝶。那些被预测会产生更强视觉迷惑效果的蝴蝶，使人们把目标瞄得更靠后。
To test whether the effects could influence attacks, the researchers recruited 100 human volunteers and carried out 3,000 virtual butterfly-catching experiments. Participants watched videos and attempted to catch butterflies by tapping a screen. Butterflies that were predicted to produce stronger visual confusion caused people to aim farther behind them.
“用活鸟和活蝴蝶进行捕食实验在很多方面都会很理想，但在实践中很可能不可能，也不符合伦理，”特罗西安科说。
"Predation experiments with live birds and butterflies would have been ideal in many ways, but likely impossible and unethical in practice," Troscianko said.
特罗西安科说，由于参与运动视觉的神经回路在脊椎动物中相当基础，研究人员希望这些发现能够在不同物种之间相互转化。
Because the neural circuits involved in motion vision are quite fundamental in vertebrates, Troscianko said, the researchers hope the findings can translate between different species.
蝴蝶面临多种捕食者，而运动迷惑未必能同样有效地骗过它们所有。
Butterflies face multiple predators, and motion confusion may not fool them all equally. "For now, we've only looked at bird vision," Troscianko said.
特罗西安科说：“目前，我们只研究了鸟类的视觉。原则上，类似的效果也可能出现在蜻蜓和食虫虻等掠食性昆虫身上。然而，它们的视觉比鸟类快得多，所以这些错觉可能对它们不起作用。事实上，蜻蜓和食虫虻确实经常成功捕食蝴蝶。”除了生物学之外，该团队的运动视觉工具还可能有实际应用，从改进飞行或战斗模拟器中运动的显示方式，到开发在视觉瞄准时保护人员、车辆、无人机或机器人运动的图案。
"In principle, similar effects could happen in predatory insects like dragonflies and robber flies. However, they have much faster vision than birds, so the illusions might not work for them. Indeed, dragonflies and robber flies do successfully hunt butterflies quite often." Beyond biology, the team's motion-vision tools could have practical applications, from improving how movement is displayed in flight or combat simulators to developing patterning that protects personnel, vehicles, drones or robots in motion when being targeted visually.
特罗西安科说：“我最兴奋的是探索我们的模型在改善道路安全和减少建筑环境中的不适和压力方面有多大用处，在建筑环境中，闪烁、移动和条纹物体可能造成伤害或危险。”
"I'm most excited to explore how useful our models could be for improving road safety and reducing discomfort and stress in the built environment, where flashing, moving and striped objects can cause harm or danger," Troscianko said.