“compression is the tendency of rewards to become less effective with repetition”
Seth Godin, Permission Marketing
In the same way that we adapt to familiar fragrances and start to no longer notice them, you can become immune to the thrill of rewards with excessive repetition.
Add some mystery to the rewards;
http://genecloud.wordpress.com/2008/05/04/223/
Think about them as treats, that you use more sparingly;
http://genecloud.wordpress.com/2008/01/09/are-the-rewards-like-good-treats/
