A form ofCONDITIONING, introduced by B.F.SKINNER that attempts to shape BEHAVIOUR by reinforcing or punishing a response which is spontaneously emitted (rather than elicitedasin CLASSICAL CONDITIONING ). The emphasis is on an organism operating on its own environment, e.g. a rat exploring a cage may happen to press a bar. If this behaviour produces the REINFORCEMENT of a food pellet it will eventually learn how to manipulate its environment to get food whenever it wants. By a careful arrangement of such reinforcements animals can be trained to perform very complex behaviours.