Humans have the tendency to pay attention to certain objects over others. When being present in a particular scene we pay attention to some parts of the scene, but not all. Humans have limited use when it comes to divided attention and we can only process so much at one time, but it is interesting on how we decipher which objects to process. This deciphering is known as selective attention, choosing certain aspects of the environment we find more important to us than others. One reasoning for this could be influence, experiencing something over and over again helps humans to pay attention to it more adequately in the long run. Sometimes when driving along the highway we naturally stop on corner ways whether there is a traffic stop or not, just because we have become “use to” this activity. When in a daze driving along the highway, I myself have stopped at many green lights not even realizing that they were green, but perceiving that this was an area to stop at and ignoring the color of the actual light.
Source: “Sensation and Perception” 9th Edition, E. Bruce Goldstien, Chapter 6.