... plus c'est la même chose. The more things change the more they stay the same. Take for instance the fascinating phenomenon of change blindness.
Check out this demonstration by Ronald Rensink, a professor of psychology and computer science. The program flashes back and forth between two versions of a picture. Can you see what's changing? It's not as easy as it sounds!
... we developed a flicker paradigm in which an original and a modified image continually alternate, one after the other, with a brief blank field between the two ... The onset of each blank field swamps the local motion signals caused by a change, short-circuiting the automatic system that normally draws attention to its location. Without automatic control, attention is controlled entirely by slower, higher-level mechanisms which search the scene, object by object, until attention lands upon the object that is changing. The change blindness induced under these conditions is a form of invisibility: it can become very difficult to see a change that is obvious once attended.In Rensink's demonstration, if you left-click on the image and then right-click there's a menu where you can change some parameters and look at other examples.
A 2005 BBC article reports on a study indicating that the parietal cortex (which is involved in concentration) plays a key role in change blindness. The article also suggests that one way magicians are able to fool us is by exploiting change blindness.