Humans can discern between 2.3 million colors - but try staring at this picture of us bursting
through the periodic table and focus on the green dot as we invert the colors. Don't
stop staring there until I say the light is traveling as a wave to your eye, and the
frequency of these wavelengths determines the perceived color of everything in this
picture and around you. Humans have trichromatic vision, meaning we have three con cells in
our retinas, each which are sensitive to different wavelengths of light; blue, green, or red.
Keep looking at the green dot and your brain will do something pretty neat. Did the image
change back to the original color? Even though you were staring at a black and white image,
your brain perceived it to be in color.
This phenomenon is known as "after imaging" - after staring long enough at the brightly
colored image, your cones slowly become fatigued and the supply of photo pigment in the respective
cones becomes exhausted, which ultimately stops sending signals to the brain.
In case of this illusion, the part of the photo where you can see cyan, the green and blue cones
become tired and as a result, there is increased activity in the fatigued red cones.
So when the image switched to black and white we see "red" - cyan's complimentary color.
Growing up, you likely learned about the primary colors red, yellow, and blue
and their respective complimentary colors. But things are more complicated when you consider that the primary
colors in your printer are magenta, yellow, and cyan, or that the screen you're watching
this on uses red, green, and blue. These are different color models, where RGB is "additive"
meaning the mixing of different lights of color creates new colors - while the other
two are "subtractive" models and absorb different wavelengths of light.
For example, when you hold a yellow object in real life, it's
actually absorbing every wavelength except yellow - that yellow light bounces back and
hits your eyes. But, when you look at this yellow object through your screen, it's actually
not yellow at all! Because your screen can only use red, green, and blue colors,
if you were to zoom in physically on anything yellow, it would actually be a combination
of red and green - and because the wavelength of yellow is between red and green, our brain
interprets this mix as yellow. So, what you're seeing here is in fact not
yellow at all, but it's stimulating a mix of your red and green cones
interprets as yellow!
While plants come in a range of colors, the predominant color is green, due to chlorophyll,
the energy absorbing pigment found in plants critical for photosynthesis. So, the effectively
attract pollinators such as bees, insects, and birds, flowers have evolved to stand out
against green. It’s why you don’t see many green flowers! And flowering plants have
even evolved a suite of different colors to attract specific pollinators - known as
pollinator syndrome. Bird-pollinated flowers are mostly red, potentially to discourage
visits from bees, as their visual system is different than birds, making it hard from
them to discriminate between red and green.
Similarly, we all have our own favourite colors, but why? One theory suggests that color preference
is gendered, where given the choice between cyan and red, men prefer cyan colors and
women prefer redder colors. Researchers hypothesize this preference has evolved from our hunter-gatherer
societies where women's visual systems were specialized to see ripe red berries against
green foliage. Another theory suggest that we like hues that we associate with pleasant
things - however pleasant and unpleasant things are often the same color - we love blue Slurpee
but not blue mold.
Investigating these questions of color had us thinking about links between science and art
So in our latest AsapTHOUGHT we asked both artists and scientists about how they
view the world.
Let us know in the comments what your favorite color is, and subscribe for more weekly science
videos.