Reality comes from perception, but perception is a sometimes thing!
(Please view the illustration in the graphic version.)
The picture on the left entitled, "After Six Beers," is exactly the same picture as the one on the previous page. Only we have turned it upside down so that you will select a different set of reference points to create the figure that you perceive now.
And the new figure you create is far different from the one you created before from the same picture! Reality, as experienced through the brain, is not as immutable as we would like to believe.
Following in the notes are a series of examples of assorted reversible figure ground tasks.
Notice how, as a the brain automatically seeks different figure-ground organization, it creates different experiences for us from the same stimulus.
NOTES: Here are some reversible figure-ground examples.
NOTES: Here are two of the same examples only a little more elaborate, on the web.