Old Or Young Lady?
Illusion #143 : Can you see both the old lady and the young lady? This image appeared in a 1915 edition of Puck.
There are different types of illusion. Physical illusions are those such as a straw that appears to bend when placed in water. Physiological illusions can be caused by excessive brightness, colour or movement. Cognitive illusions are those that seem to contradict our logic, and even knowing that it's a trick doesn't help.