Freud created a description of the mind that emphasizes the major role played by unconscious drives, particularly those of sexuality. His theories, which struck many contemporaries as sordid and threatening, represents the most recent democratization or leveling of the old hierarchical conception of mind. Freud created an entirely new approach to the understanding of human personality by his demonstration of the existence and force of the unconscious. In addition, he founded a new medical discipline and formulated basic therapeutic procedures that in modified form are applied widely in the present-day treatment of neuroses and psychoses. Although never accorded full recognition during his lifetime, Freud is generally acknowledged as one of the great creative minds of modern times.
             B. F. Skinner's entire system is based on operant conditioning. The organism is in the process of "operating" on the environment, which in ordinary terms means it is bouncing around it world, doing what it does. During this "operating," the organism encounters a special kind of stimulus, called a reinforcing stimulus, or simply a reinforcer. This special stimulus has the effect of increasing the operant -- that is, the behavior occurring just before the reinforcer. This is operant conditioning: "the behavior is followed by a consequence, and the nature of the consequence modifies the organisms tendency to repeat the behavior in the future."
             Imagine a rat in a cage. This is a special cage (called, in fact, a "Skinner box") that has a bar or pedal on one wall that, when pressed, causes a little mechanism to release a foot pellet into the cage. The rat is bouncing around the cage, doing whatever it is rats do, when he accidentally presses the bar and -- hey, presto! -- a food pellet falls into the cage! The operant is the behavior just prior to the reinforcer, which is the food pellet, of course. In no time at al...