Your favorite color might change without you knowing it
Color is something that’s easy to take for granted. You learn color names as a toddler, maybe practice some “green means go! red means stop!” in kindergarten, and then after that you probably don’t have to worry much about it until it’s time to pick beige or eggshell for your living room walls. In all of these scenarios, we usually don’t even notice that color perception is dynamic, from culture to culture, person to person, and even from month to month within the same individual. Not every change can be explained, but it’s safe to say a lot of these shifts are thanks to your brain’s role in actually appreciating which color is which.
Sensing then perceiving
From the perspective of physics, colors are just different wavelengths of light being reflected off surfaces to our eye. In our eye, our cones are activated by different portions of the red, green or blue wavelengths, and they send a signal to our brain. Our brain then sifts and packages this information, letting us identify an object as blue. Or maybe purple? Teal?
The squishiness of this system partly comes from societal constructs. While just about every human can agree on a core set of colors being red, blue, green and yellow, which wavelengths of light count as each of those colors is up to some debate. Different cultures seem to define different wavelengths as a canonical red, for instance. Some cultures are more specific about certain ranges of light, such as Russian having separate words for blue vs. light blue.
Shifts of the sun
Yellow seems to deviate from these cultural biases though, as most people around the world agree on what would be an unadulterated yellow, as least most of the year. The shifts with yellow seem to happen on a personal basis, as a study found people’s pick for true yellow was different if they were asked in the middle of winter or in summer. The test was done in an otherwise isolated environment, so ambient light changes weren’t the culprit— each test participant seemed to have shifted their concept of yellow slightly. It’s thought that this may be physiological in order to help maintain visual acuity when outdoor light conditions change dramatically in gray, snowy weather versus vibrant summer skys.
My first grader asked: Well, what does the yellow look like in winter? Is it darker? Lighter?
The shift in wavelength only affected the hue, not the brightness. But the change measured was that summer yellows were slightly shorter wavelengths, meaning more green, whereas in the winter people’s true yellow had longer wavelengths, and thus a “warmer” tone to it.
Source: People's Color Perception Changes with the Seasons by Tia Ghose, Live Science