consists of a screen projection of a typical street scene that
blinks momentarily and reappears after making a single change
in the picture, such as removal of a parking meter.
challenged to identify the change but usually cant unless
their attention is focused on the part of the image that changes.
Sudden changes to a scene usually attract attention, but when
the blink interrupts the whole scene, it prevents any changes
from being noticed. Without the blinks the changes are obvious.