You can always "see" your nose.

The human brain is capable of amazing things, but in order to do those things, it needs to block out distractions through a process called unconscious selective attention. The nose is one of those distractions. In his landmark 1960s study, Ulric Neisser discovered this phenomenon after he asked participants to count the number of times basketball players passed a ball in a video. What the large majority failed to notice in the video was a girl walking through the middle of the court with an umbrella, because they were so focused on counting.