Change blindness.

Change blindness is a phenomenon in which major changes to a visual scene go unnoticed. There are many methods of inducing change blindness, for example, by presenting a blank image between presentation of the original and changed pictures. Change blindness is thought to occur when visual attention is prevented from being drawn to the change. Detecting the changes requires a comparison between the changed state of the picture and a visual memory of its original state. Without visual attention the memory may not be retrieved at all or the available memory may lack sufficient visual detail for a change to be registered. Change blindness is employed as a tool for studying visual attention and has obvious real-world implications for tasks such as driving