You are sitting in an arena watching the end of a very close basketball game, and you fail to notice that one of the referees has removed his shirt. this an example of

Inattentional blindness is the psychological restriction of attention that has nothing to do with any defect with the person's vision. Also known as perceptual blindness, this normally occurs when a person fails to notice an unexpected activity that was directly in their line of sight and would normally be stimuli even though it went unnoticed.