Data from: Eye-spots in Lepidoptera attract attention in humans

Many prey species exhibit defensive traits to decrease their chances of predation. Conspicuous eye-spots, concentric rings of contrasting colors, are one type of defensive trait that some species exhibit to deter predators. We examined the function of eye-spots in Lepidoptera to determine whether they are effective at deterring predators because they resemble eyes (‘eye mimicry hypothesis’) or are highly salient (‘conspicuous signal hypothesis’). We recorded the gaze behavior of men and women as they viewed natural images of butterflies and moths as well as images in which the eye-spots of these insects were modified. The eye-spots were modified by removing them, scrambling their colors, or replacing them with elliptical or triangular shapes that had either dark or light centers. Participants were generally more likely to look at, spend more time looking at and faster to first fixate the eye-spots of butterflies and moths that were natural compared to ones that were modified, including the elliptical eye-spots with dark centers that most resembled eyes as well as the scrambled eye-spots that had the same contrast as the natural eye-spots. Participants were most likely to look at eye-spots that were numerous, had a large surface area, and located close to the insects’ heads. Participants’ pupils were larger when viewing eye-spots compared to the rest of the insects’ body, suggesting a greater arousal when viewing eye-spots. Our results provide mixed support for the ‘conspicuous signal’ hypothesis and suggest that eye-spots may be effective at deterring predators because they are highly-conspicuous signals that draw attention.

诸多被捕食物种会演化出防御性状，以降低自身被捕食的概率。显眼眼斑（eye-spots）——即带有对比色的同心环状结构——是部分物种演化出的用以威慑捕食者的防御性状之一。本研究针对鳞翅目（Lepidoptera）昆虫的眼斑功能展开探究，旨在验证眼斑威慑捕食者的有效机制究竟是其形似眼部的拟态效果（眼拟态假说，eye mimicry hypothesis），还是其极高的视觉显著性（显眼信号假说，conspicuous signal hypothesis）。我们记录了男女受试者在观看天然蝶类与蛾类自然图像，以及经眼斑修饰的同类昆虫图像时的眼动行为。研究人员通过移除眼斑、打乱其色彩排布，或是将其替换为带有深色或浅色中心的椭圆形或三角形结构，对眼斑进行修饰。整体而言，相较于经修饰的眼斑，受试者更易注视天然蝶蛾的眼斑，且注视时长更长、首次注视眼斑的速度更快；此类修饰后的眼斑包括最形似眼部的深色中心椭圆形眼斑，以及与天然眼斑对比度一致的色彩打乱眼斑。受试者最易关注那些数量较多、表面积较大且靠近昆虫头部的眼斑。受试者在注视眼斑时的瞳孔尺寸，相较于注视昆虫身体其他部位时更大，这表明注视眼斑会引发更高程度的唤醒水平。本研究结果为显眼信号假说提供了部分支持，并表明眼斑之所以能够有效威慑捕食者，或许是因为其作为高显著性视觉信号能够吸引注意力。