In Skinnerian operant conditioning, when a certain behavior has no consequences (that is, it produces neither a positive nor a negative response), it will occur less frequently.
Example: A rat learns that when it presses a certain lever, it will receive a food pellet. It begins to press the lever more and more often. Once it stops being rewarded with food, however, it will soon stop pressing the lever again.
Grinnell, R. (2009). Extinction. Psych Central. Retrieved on May 4, 2016, from http://psychcentral.com/encyclopedia/extinction/