Why are all banners with yellow characters on a red background?

The meaning of "yellow characters on green background" is that the red background presents yellow handwriting information. Its "red" and "yellow" are concepts of fuzzy sets;

1. Red can stimulate and excite the nervous system, accelerate the heartbeat and produce fiery emotions. ?

2. Yellow can inspire people's intelligence, strengthen logical thinking, make the pulse tend to be normal, and produce positive and exciting driving force.

3. Green can relieve eye fatigue, make nervous nerves relax, enhance the sensitivity of ideological activities, and absorb noise, which is good for active people and depressed people. According to the experimental results of fundus reflection spectrophotometry, we use different wavelengths of light as light source to find out the difference of human visual pigment density, and then see if the wavelength of light source has anything to do with this difference. Rushton et al. conducted experiments on people with visual function of fovea cells. First, the reflectivity of unbleached fovea was measured with different wavelengths of light, then the eye was irradiated with white light to completely bleach the visual pigment, and the change of visual pigment density under different wavelengths of light (not the optical density itself) was measured to get a curve. Then, the subjects were placed in a 7-meter completely dark environment for 7 minutes to regenerate the pyramidal cytochrome, and then the visual pigment was bleached with a certain degree of red light, and then the change of the optical density of the visual pigment was measured to get the curve. Its peak shifts to the yellow band with a wavelength of 580 nm. The subjects were subjected to dark adaptation to regenerate pyramidal cytochrome, and then bleached with green light with sufficient intensity, such as measuring the change of forward-looking pigment density to get the curve. The peak value of this curve is about 540nm, and a peak curve is obtained.