Why Humans See More Colors than Dogs, but Fewer than Birds and Insects

Theoretical Physicist
Over a year ago

“In the nineteenth century, with Maxwell’s Synthesis of the Laws of Electricity and Magnetism, physicists started to realize that what we perceive as light is deeply understood as a kind of disturbance of electric and magnetic fields.” Frank Wilczek says. “That gave us a new concept of the possibilities of perception of light, that show us we’re missing a lot.”

In fact, there is a lot to light that we as humans can’t see.

“What we perceive as color — what we perceive as light — corresponds to a very narrow band of frequencies, out of an infinite continuum. Not only that, but within that band we take three averages.”

These averages are made up of the three primary colors. These three colors mix and match to make up the rest of our field of vision, which is known as tri-chromatic vision.

“In computer displays, there are three different kinds of lighting elements used.” Wilczek explains. “When you see on your menu, the choice of millions of different colors, that doesn’t mean different lighting arrangements or possibilities. It means different combinations, different relative intensities of just three. Any perceived color can be synthesized from three basic colors.”

Not all animals have three cones of vision, dogs are known to have only two, while some other animals have more. These animals not only can see more colors than we as humans do, but can “sample” light in different ways than humans, such as infrared and ultra violet light. For now, in our current natural state of being, we can’t see them.

“Our perception of sound, in one way, is much richer.” Wilczek says. When a chord is played on an instrument, we are able to differentiate between the notes being played, we hear them as separate notes played at the same time. But when two waves of light, two colors hit each other, such as red and blue, we see them as one beam of light: purple.

“Our perception of that mixture is indistinguishable from a pure spectral yellow such as you’d see in a rainbow. It’s as if in music, when you play a C and a G together, instead of hearing a chord, you just heard the note E.”

This has a lot to do with how fast the waves oscillate. Sound waves are relatively slower, allowing our brains to keep up with the way they move, while light waves oscillate faster.

“The way we process that is quite different, it’s an all or none process where photons get absorbed and trigger changes in the structure of proteins. We have three kinds of proteins, and three different kinds of cone cells, that give us three kinds of average responses. And that’s why you can synthesize any perceived color with just three.”