Data from: Experimental evidence that primate trichromacy is well suited for detecting primate social colour signals

Primate trichromatic colour vision has been hypothesized to be well tuned for detecting variation in facial coloration, which could be due to selection on either signal wavelengths or the sensitivities of the photoreceptors themselves. We provide one of the first empirical tests of this idea by asking whether, when compared with other visual systems, the information obtained through primate trichromatic vision confers an improved ability to detect the changes in facial colour that female macaque monkeys exhibit when they are proceptive. We presented pairs of digital images of faces of the same monkey to human observers and asked them to select the proceptive face. We tested images that simulated what would be seen by common catarrhine trichromatic vision, two additional trichromatic conditions and three dichromatic conditions. Performance under conditions of common catarrhine trichromacy, and trichromacy with narrowly separated LM cone pigments (common in female platyrrhines), was better than for evenly spaced trichromacy or for any of the dichromatic conditions. These results suggest that primate trichromatic colour vision confers excellent ability to detect meaningful variation in primate face colour. This is consistent with the hypothesis that social information detection has acted on either primate signal spectral reflectance or photoreceptor spectral tuning, or both.已有假说提出，灵长类三色色觉（Primate trichromatic colour vision）具备极佳的适配性，可精准识别面部色彩的变化，该适配性的来源可能是对信号波长的选择，或是感光细胞自身敏感度的选择。本研究通过对比其他视觉系统，检验灵长类三色色觉所获取的信息是否能提升检测雌性猕猴发情接受期面部色彩变化的能力，这是该假说的首批实证检验之一。我们向人类受试者展示同一猕猴的成对面部数字图像，并要求其选出处于发情接受期的猕猴面部图像。本次测试的图像分别模拟了普通狭鼻类灵长类（catarrhine）三色色觉、另外两种三色视觉条件，以及三种二色视觉条件下的视觉效果。结果显示，在普通狭鼻类三色色觉、以及LM视锥细胞色素（LM cone pigments）间距较窄（常见于雌性阔鼻类灵长类（platyrrhines））的三色色觉条件下，受试者的表现均优于等间距三色色觉条件，或任意一种二色视觉条件。上述结果表明，灵长类三色色觉可高效识别灵长类面部色彩中具备生物学意义的变化。这一结果与下述假说一致：自然选择通过社交信息识别的压力，作用于灵长类信号的光谱反射特性，或是感光细胞的光谱调谐特性，或同时作用于两者。