"While Pavlov's work dealt with a reflexive reaction to a conditioned stimulus, Skinner became interested in creating a specific behavioral reaction to a stimulus by adding a reinforcer. A reinforcer can be either a reward or a punisher. A reward is anything that increases the frequency of an action; a punisher is anything that decreases its frequency. When we are rewarded for a certain behavior, we are likely to repeat that behavior. When we are punished for a certain behavior we are likely to stop. This type of learning is active and voluntary; it depends on the actions of the learner. Because the definition of a reinforcer is based on its effectiveness, it's important to remember that a reward for one person may not be meaningful, and thus not a reward, for another. Similarly, what is a reward in one context may not be somewhere else. A rat in a basic Skinner box A rat in a basic Skinner box Skinner showed that both animals and people would perform certain behaviors for a reward. In his experiments with rats and pigeons, Skinner showed how animals could learn to press a lever to get a food reward. When the animals were first introduced to the test box they moved around randomly. When they accidentally depressed the lever, a food pellet was dispensed. They quickly learned to depress the lever on purpose to get a pellet. He also shaped behaviors that are more complicated by reinforcing them step by step. Skinner called his approach ""operant conditioning"" because the animal's behavior actually operated on the environment (pressing the lever) in response to the anticipated outcome (getting a food reward). Rewarding to encourage good behavior and punishing to discourage bad is something most of us do instinctively; it's common sense. Operant conditioning had a long history in animal training even before it was ever defined. Colonel Konrad Most, who published ""Training Dogs: A Manual"" in 1910, was using many of the same principles that Skinner studied, decades before he described them. Col. Most's training methods seem somewhat harsh by today's standards, but he is considered by many to be the father of modern dog training. Most, and other trainers used both rewards and punishers to shape and reinforce desired behavior. Next, we'll look at how reinforcers are used in animal training."