Inattentional Blindness

Inattentional Blindness, also known as perceptual blindness, is an event where the effected person doesn't see new and unexpected things that suddenly appear within their visual field. This phenomenon is believed to be a side-effect of excessive stimuli in the visual field (too many things to keep track of at the same time) and can cause a person to miss important, but unexpected, items in their vicinity.

This phenomenon can effect anyone and isn't caused by any known cognitive deficits. This term was first used by Arien Mack and Irvin Rock in 1992, and was used as the title of a book written by Mack that was published by the MIT press in 1998.