What is classical conditioning ? elements of classical conditioning, basic principles of classical conditioning, extinction, spontaneous recovery.

Classical conditioning 

Ivan Pavlov :- He was a Russian physiologist [ a person who studies the workings of the body ] .He was studying the digestive system in his dogs, Pavlov had built a device that would accurately measure the amount of saliva produced by the dogs when they were fed a measured amount of food. The food causes a particular reaction, the salivation. A stimulus can be defined as any object , event, or experience that causes a response, the reaction of an organism. In the case of Pavlov's dogs, the food is the stimulus and salivation is the response. Pavlov soon discovered that his dogs began salivating when they weren't supposed to be salivating. Some dogs should start salivating when they saw the lab assistant bringing their food, others when they heard the clatter of the food bowl from the kitchen, and still others when it was the time of day they were usually fed.

Elements of Classical Conditioning

• Pavlov eventually identified several key elements that must be present and experienced in a particular way for conditioning to take place.
• Unconditioned stimulus-The original, naturally occurring stimulus is called the unconditioned stimulus [ UCS ]. The term unconditioned means " unlearned ". This is the stimulus that ordinarily leads to the involuntary response. In the case of Pavlov's dogs, the food is the unconditioned stimulus.
• Unconditioned Response :- The automatic and involuntary response to the unconditioned stimulus is called the unconditioned response [ UCR ] for much the same reason. It is unlearned and occurs because of genetic " wiring " in the nervous system. For example, in Pavlov's experiment, the salivation to the food is the UCR [ unconditioned response ].
• Conditioned Stimulus Pavlov determined that almost any kind of stimulus could become associated with the unconditioned stimulus [ UCS ] if it is paired with the UCS often enough. In his original study, the sight of the food dish itself became a stimulus for salivation before the food was given to the dogs. Every time they got food [ to which they automatically salivated ], they saw the dish. At this point, the dish was a neutral stimulus [ NS ] because it had no effect on salivation . After being paired with the food so many times , the dish came to produce a salivation response, although a somewhat weaker one, as did the food itself. When a previously neutral stimulus, through repeated pairing with the unconditioned stimulus, beings to cause the same kind of involuntary response, learning has occurred. The previously neutral stimulus can be called a conditioned stimulus [ CS ]. { conditioned means " learned ", and, as mentioned earlier, unconditioned means " unlearned " }. 
• Conditioned Response The response that is given to the CS [ conditioned stimulus ] is not usually quite as strong as the original unconditioned response [ UCR ], but it is essentially the same response. However, because it comes as a learned response to the conditioned stimulus [CS] it is called the conditioned response [ CR ]. 

Before conditioning :- 

During conditioning :-

                                 

After conditioning :-

Classical Conditioning :-

Before conditioning takes place, the sound of the metronome does not cause salivation and is a neutral stimulus, or NS. During conditioning, the sound of the metronome occurs just before the presentation of the food, the UCS. The food causes salivation, the UCR. When conditioning has occurred after several pairings of the metronome with the food, the metronome will begin to elicit a salivation response from the dog without any food. This is learning and the sound of the metronome is now a CS and the salivation to the metronome is the CR.

Basic principles :-

1. The CS must come before the UCS. If Pavlov sounded the metronome just after he gave the dogs the food, they did not become conditioned [ Rescorla, 1988 ].
2. The CS and UCS must come very close together in time ideally, no more than 5 seconds apart. When Pavlov tried to stretch the time between the potential CS and the UCS to several minutes, no association or link between the two was made. 
3. The neutral stimulus, must be paired with the UCS several times, often many times, before conditioning can take place [ Pavlov, 1926 ].
4. The CS is usually some stimulus that is distinctive or stands out from other competing stimuli. The metronome, for example, was a sound that was not normally present in the laboratory and, therefore, distinct.

Extinction :-

When the metronome's ticking [CS or conditioned stimulus] was repeatedly presented in the absence of the UCS [ unconditioned stimulus or food ], in this case, the salivation [ CR or conditioned response ]  

" diet out " in a process called extinction.

Spontaneous Recovery :- 

Pavlov took the metronome back out and set it ticking, the dogs all began to salivate, although it was a fairly weak response and did not last very long. This brief recovery of the conditioned response provides that the CR is " still in there " somewhere [ remember learning is relatively permanent ]. It is just suppressed or inhibited by the lack of an association with the unconditioned stimulus of food [ which is on longer reinforcing or strengthening the CR ]. As time passes, this inhibition weakens especially if the original conditioned stimulus has not been present for a while. In spontaneous recovery the conditioned response can briefly reappear when the original CS returns, although the response is usually weak and short-lived.

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