Brains are great at pattern recognition (lots of studies). This includes ratios. Your shade of color is not a good example, because it's just a single value, not relative to anything on its own. But if you have multiple colors, there will be various relationships/ratios between physical properties of the colors (wavelength, intensity etc.). Similar in music, 1:2 frequency ratio is recognized as an octave. Strongest ratios (i.e. strong pattern) are usually the simple ratios like 1:2, 1:3 & 2:3, etc. However, science hasn't been able to find out, if we can recognize Golden ratio because of the Fibonacci sequence pattern that is often found in nature or if it's to us just a ratio that is close to a simpler ratio like 5:3.