Learning is a relatively permanent or stable change in behavior as a result of experience. Such changes may be associated with certain changes in the connections within the nervous system. Learning occurs by various methods, including classical conditioning, operant conditioning, and social learning. Cognitive factors are also implicated in learning, particularly in humans. learning.jpgClassical conditioning was first described by Pavlov, and is sometimes called Pavlovian conditioning. Classical conditioning occurs when a neutral stimulus, paired with a previously meaningful stimulus, eventually takes on some meaning itself. For example, if you shine a light in your fish tank, the fish will ignore it. If you out food in the tank, they will typically swim to the top to get the food. If, however, each time you feed the fish, you shine the light in the tank before putting in the food, the fish will begin to learn about the light. Eventually, the light alone will cause the fish to swim to the top, as if food had been placed in the tank. The previously neutral light has now taken on some meaning. If you are having a difficult time comprehending the different parts of classical conditioning, note that conditioning is another word for learning. For instance, unconditioned response is just another way of saying unlearned response. Psychologists use specific terms for the various stimuli in classical conditioning. The conditioned stimulus (CS) is the initially neutral stimulai, in our example, the light. The unconditioned stimulus (US) is the initially meaningful stimulus. In our example, the US is food. The response to the US does not have to be learned; this naturally occuring response is the unconditioned response (UR). In our example the UR is swimming to the top of the tank. The conditioned response (CR) is the response to the CS after conditioning. Again, the example the CR is swimming to the top.Secondary reinforcer.gif