Instrumental Conditioning
Process in which animals learn about the relationship between their behaviors and their consequences.
Operant conditioning occurs when a Behavior (as opposed to a Stimulus) is associated with the occurrence of a significant event.
Example
In the best-known example, a rat in a laboratory learns to press a lever in a cage (called a “Skinner box”) to receive food. Because the rat has no “natural” association between pressing a lever and getting food, the rat has to learn this connection. At first, the rat may simply explore its cage, climbing on top of things, burrowing under things, in search of food. Eventually while poking around its cage, the rat accidentally presses the lever, and a food pellet drops in. This voluntary behavior is called an operant.
Operant
A behavior that is controlled by its consequences. The simplest example is the rat’s lever-pressing, which is controlled by the presentation of the reinforcer.
 behavior, because it “operates” on the environment (i.e., it is an action that the animal itself makes).