Please read and memorize the following words: bed, rest, awake, tired, dream, wake, snooze, blanket, doze, slumber, snore, nap, peace, yawn, drowsy. Look away from the screen and write down the words you remembered.
Once you've done so, please highlight this paragraph as if you were highlighting a paragraph in Word (double-click and drag your mouse down): If you're like most people, you remember the word sleep. Guess what: Sleep was not one of the words listed.
That's the Deese-Roediger-McDermott (DRM) effect (described here), and it's a powerful way of illustrating that we can all be tricked into creating false memories.