Try The Stroop Test
The following test, often called the "Stroop Test,"
was invented by psychologist John Ridley Stroop in 1935. It is
based on the conflict between the colors your eyes see and the
tendency to want to read the words. It may be a good "brain
game" as well, one you can use to exercise your brainpower.
To try it, use a clock or stopwatch. Look at the words consecutively,
saying aloud the color in which each word is written, rather
than reading the word. See if you can get it right the first
time, and time yourself to see how long it takes.
Have your friends try this as well. If you can print out this
page, there is an easier way to do this brain teaser more quickly.
Just turn it upside down. When it it right side up your brain
is working to overcome its tendency to read the words themselves.
Your brain is not as likely to try to read the words when they
are upside down, making it easier to state the colors.
Also, you can do this more quickly if you are fluent in another
language. Just call out the colors in that language. Concentrating
on the colors in another language seems to take attention away
from the English words and so make them less distracting.
Now for the real brain exercise: Can you think of a way to
put this phenomenon to some productive use? Let me know.