Conditioning means to associate. This pattern of learning is based on association and it is the simplest method of learning. In a given situation or environment, when more frequent and predictable responses are given to a stimuli, it is called conditioning. For example: different sound of the school bell is associated with different activities. In this sort of learning, a series of sensations are experienced by an individual, so on presentation of a particular stimuli, it evolves response associated with it. Thus, we can say that conditioning means a chain of experience which makes us realize the presence of many associated stimuli when one stimulus is there. A Russian physiologist Ivan Petrovich Pavlov (1849-1936) was the first investigator in this type of learning. It is also called classical conditioning. In this, Pavlov performed many experiments based on the digestion system to explain conditioning. Experiment: In this experiment, Pavlov made a stand on which a dog was tied. The dog was tied in such a manner that his dripping saliva would fall in the measuring glass. Then Pavlov presented food in front of the dog. Seeing the food, the hungry dog started salivating. It was a natural response. Now, Pavlov changed the strategy. A beli was sounded before the dog was served food. This practice was repeated for some days. In the begining the dog started saliavating when the food was presented to him. But later on, the saliva started to secret, even when the dog heard only the sound of the bell. So, it can be said that the dog learnt how to react to a conditioned stimulus (C.S.). The important features of classical conditioning are as follow: 1. Unconditioned stimulus (UCS) 2. Unconditioned response (UCR) 3. Conditioned stimulation (CS) 4. Conditioned response (CR) 5. Reinforcement 6. Extinction 7. Stimulus generalization 8. Stimulus Discrimination Before conditioning Food (USC) + Salivation (UCR) During conditioning Sound bell(CS) + Food (UCS) → Salivation(UCR) After conditioning Bell (CS) → Salivation (Eastablishing Conditioning) Establishment of Conditioning