Data from: Relative advantages of dichromatic and trichromatic color vision in camouflage breaking

There is huge diversity in visual systems and color discrimination abilities, thought to stem from an animal’s ecology and life history. Many primate species maintain a polymorphism in color vision, whereby most individuals are dichromats but some females are trichromats, implying that selection sometimes favors dichromatic vision. Detecting camouflaged prey is thought to be a task where dichromatic individuals could have an advantage. However, previous work either has not been able to disentangle camouflage detection from other ecological or social explanations, or did not use biologically relevant cryptic stimuli to test this hypothesis under controlled conditions. Here, we used online “citizen science” games to test how quickly humans could detect cryptic birds (incubating nightjars) and eggs (of nightjars, plovers and coursers) under trichromatic and simulated dichromatic viewing conditions. Trichromats had an overall advantage, although there were significant differences in performance between viewing conditions. When searching for consistently shaped and patterned adult nightjars, simulated dichromats were more heavily influenced by the degree of pattern difference than were trichromats, and were poorer at detecting prey with inferior pattern and luminance camouflage. When searching for clutches of eggs—which were more variable in appearance and shape than the adult nightjars—the simulated dichromats learnt to detect the clutches faster, but were less sensitive to subtle luminance differences. These results suggest there are substantial differences in the cues available under viewing conditions that simulate different receptor types, and that these interact with the scene in complex ways to affect camouflage breaking.视觉系统与色彩辨别能力存在显著多样性，学界普遍认为其源自动物的生态学特征与生活史。许多灵长类物种存在色觉多态性：多数个体为二色视觉者（dichromat），仅部分雌性为三色视觉者（trichromat），这表明自然选择有时会青睐二色视觉。侦测伪装猎物被认为是二色视觉者可能具备优势的任务场景。然而，既往研究要么无法将伪装侦测与其他生态学或社会学解释相区分，要么未使用符合生物学相关性的隐蔽刺激物，在可控条件下验证这一假说。本研究通过线上"公民科学（citizen science）"游戏，测试人类在三色视觉与模拟二色视觉的观看条件下，侦测隐蔽鸟类（孵卵的夜鹰（nightjar））及其卵（夜鹰、鸻（plover）与燕鸻（courser）的卵）的速度。尽管不同观看条件下的检测性能存在显著差异，但三色视觉者整体具备优势。当搜寻形态与图案均较为一致的成年夜鹰时，模拟二色视觉者比三色视觉者更易受图案差异程度的影响，且在侦测图案与亮度伪装效果较差的猎物时表现更差。当搜寻卵窝（其外观与形态比成年夜鹰更具变异性）时，模拟二色视觉者能更快学会侦测卵窝，但对细微的亮度差异敏感度更低。上述结果表明，模拟不同受体类型的观看条件下可获取的视觉线索存在显著差异，且这些线索会与场景以复杂方式相互作用，进而影响伪装破获效率。