“If what you’re seeing has changed, and the patterns of light become much more noticeable ... because the cells in your eyes ...

In vertebrate retinas, specialized photoreceptors responsible for color vision (cone cells) arrange themselves in patterns ...

physical light reflectance measurements, and behavioral experiments, has allowed researchers to quantify color patterns as birds would see and use them (Vorobyev & Osorio 1998; Endler & Mielke 2005).