Color Scope is a series that explores our perception of color, it's use across cultures and other curiosities. Each month we examine a new color.
Written and narrated by Dr. James Fox. Conceived and produced by Sarah-Grace Mankarious.
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As light enters a 'blue' eye, it is scattered to create a blue hue, there is no actual blue pigmentation in the eye. The only difference between a brown eye and a blue eye is this very thin layer of pigment on the surface. If you take that pigment away, light can enter the eye’s stroma and only reflects back the shortest wavelengths, which are at the blue end of the spectrum.
The Mandarin Fish and the aptly named Psychedelic Fish have blue pigment. Other vertebrates that appear blue have layers of crystals that reflect light at shorter wavelengths to create a structural color.
It has been shown that some ancient languages like Greek, Japanese and Hebrew never used the word blue, leading to questions about whether they were able to see it or if they simply couldn't describe it. Ancient Egyptians were the first civilization to have a word for it, while some tribes today still don’t acknowledge the color blue.
Cones are the part of our eye that can detect all colors. However, in very low level light these cones can no longer function and our eyes become more sensitive to light with a higher wavelength; at the blue end of the spectrum. This is known as the Purkinje Effect. So in when in dim light, blue lights like emergency vehicle lights, appear brighter.
This is down to a phenomenon called 'atmospheric perspective'; when the amount of atmosphere affects the color of objects. The atmosphere contains dust and water particles which causes light to scatter when it passes through them and since blue has the shortest wavelength, this is what people see when the light is scattered.
Dr. James Fox is an academic and BAFTA-nominated broadcaster. He is a Fellow of Gonville & Caius College, Cambridge, where he teaches History of Art. He has been obsessed with color since he was a boy, and is currently writing a book called The Meaning of Colour. Follow him on Twitter @doctorjamesfox.