Many photographic, pictorial or camouflage illusions are not perpetual. They are ‘one time illusions’ because they are only effective until we are aware of the misinterpretation. After that we cannot usually revert to the earlier interpretations, at least not in the short term. Language is like this: once we can read, it is virtually impossible for us to see written words as just lines on paper. Our brains are so well programmed to paying attention to what the words actually mean, that we cannot help but read them.
These illusions demonstrate that our consciousness can override interpretations the brain has already developed. Even more importantly, they demonstrate how quickly and effectively the human brain can learn.
Part One
Look at each of the following images. What do you perceive and not perceive in each?
 |
 |
| A | B |
|---|
 |
| C |
|---|
Scroll down for the answer once you've had a good look.
Answers:
A. world map in negative
B. cruise ship
C. cow
Part Two
Now that you know what's in each image, look at them again. Can you make your brain go back to seeing meaningless shapes on paper — the same shapes you saw until you read what they actually were? Most people cannot do this.