There are limitations to the brain and its working is also so complicated that one is not able to fully comprehend the dimensions of the nature of the operations of the human brain. However, what is evident is that there are a number of tricks and puzzles which cannot be solved by the simple brain operation alone.
Optical illusions are the most popular and one example is the set of parallel lines which appear crooked when the bounding lines are broken and joined unevenly. The mirage in the desert is another optical illusion where we see images drifting and appearance of water where there is none.
         Similarly word puzzles are made where the usage of words and their grammatical connotations are intermingled to make the brain dizzy with the implications.
The way the brain perceives objects (binocular vision) is another area where there is plenty of scope for tricks. The person is asked to stare at a particular image for a period of time and when he looks away, he sees another image in his mind.
Mind teasers are an interesting way to spend time and conjurers and magicians use the optical illusion in many of their magical acts. Teasers are the way the people as attention is drawn to one fact or object while the magician quietly moves another object into a corner in the dark, ready for exposure to the audience when the lights come on.