Check out the following exercise, guaranteed to freak you out.
There's no trick or surprise.  Just follow these instructions and answer the
question one at a time and as quickly as you can!
     Again, as quickly as you can but don't advance until you've done
each of  them...really!
 

Now, arrow down (but not too fast, you might miss something). . .
 

What is:
 
 
 
 

1+5
 
 
 
 
 
 

2+4
 
 
 
 
 
 

3+3
 
 
 
 
 

4+2
 
 
 
 
 
 

5+1
 
 
 
 

Now repeat saying the number 6 to yourself as fast as you can for
15 seconds.
 
 

Then scroll down.
 
 
 
 
 
 

QUICK!  THINK OF A VEGETABLE!  Then arrow down.
 
 
 
 
 
 

Keep going.
 
 
 
 
 
 
 

You're thinking of a carrot, right?
 

If not, you're among the 2% of the population whose minds are
warped enough to think of something else.  98% of people will
answer with carrot when given this exercise.  Freaky, huh?