Psychologists distinguish between two ways of perceiving the world around us and processing information – top down vs. bottom up processing. In top down processing, we draw on our past experiences and “fill in the blanks” when we encounter a particular place or situation. We don’t have to notice every detail, because a few signs prove sufficient to let us know what we are seeing. We walk into a library, and we know quickly based on a few visual cues that we are in a library. We don’t need to attend to all the details. In bottom up processing, we start by perceiving all the little details, and we put the pieces of the puzzle together gradually.
Source: Think Like a Traveler