Change blindness is the failure to detect non-trivial changes in the visual field. The failure to see things changing right before your eyes may seem like a design fault, but it is actually a sign of evolutionary efficiency.
The term ‘change blindness’ was introduced by Ronald Rensink in 1997, although research in this area had been going on for many years. Experiments have shown that dramatic changes in the visual field often go unnoticed whether they are brought in gradually, flickered in and out, or abruptly brought in and out at various time intervals. The implication seems to be that the brain requires few details for our visual representations; the brain doesn’t store dozens of details to which it can compare changes (Simons and Levin: 1998). The brain is not a video recorder and it is not constantly processing all the sense data available to it but is inattentive to much of that data, at least on a conscious level.
Change detection in films is notoriously poor when the change occurs during a cut or pan, as demonstrated by the color-changing card trick video and a number of other videos where a different actor appears after a cut, without the change being noticed by most viewers. Some experiments have shown that a person may be talking to someone (behind a counter, for example) who leaves (bends down behind the counter or exits the room) and is replaced by a different person, without the change being noticed.
Apparently, change blindness is due to the efficient nature of our evolved visual processing system, but it also opens the door to being deceived, much to the delight of magicians and sleight-of-hand con artists.
More examples of change blindness:
- Change Blindess (farisyakob.typepad.com)
- Did You Not Notice or Not Remember? (theness.com)
- Another Cool Change Blindness Video: The Color Changing Card Trick (capitalogix.typepad.com)