RED excites and enrages. It can symbolize fury as well as passion; love or blood. It’s the color of sex and death.
Yellow is the most visible color of the spectrum.
The human eye processes yellow first. This explains why it is used for cautionary signs and emergency rescue vehicles.
Peripheral vision is 2.5 times higher for yellow than for red.
Yellow has a high light reflectance value and therefore it acts as a secondary light source.
The English “to feel blue” has no equivalent in other languages while in German “blau sein” (literally: to be blue) means to be drunk or in Russian “голубой” (literally: light blue) means to be homosexual.