Can t process it all. Only so much the brain can process that the eye can see.
Perception is selective.
Factors influencing perception Background Intensity Extensity Concreteness Contrast and velocity Impressivity Background Can cause confusion. Louder, brighter or more vivid, the greater the chances people will perceive it. Extensity Effect of size. Larger objects get more attention. Elephants, Godzilla, billboards Competition.