Classical Conditioning

Classical conditioning, discovered in the late nineteenth century, is the ability to associate a relationship between two different stimuli. As Pavlov was investigating the digestive system of dogs, he discovered that saliva was produced as the dogs where presented with food. He then found that the dogs produced the same response when a chime was sounded before food was presented, even if the food was not produced on a particular occasion. This shows that the dogs associated the chime, with receiving food.

There are two different types of stimuli associated with the psychology of learning; they are unconditioned (UCR) and conditioned (CR) responses. UCR is a response to a particular stimuli that is a natural instinct to a given stimuli. For the case above, the UCR would be the saliva at the presence of food. On the other hand, CR is the learnt response to a situation. The dogs associated, in only 4-5 trials, that the sound of the chime represented them being fed.

The amount of time that passes between a CS and a UCS has a large impact connecting the two different events together. If an extended period of time passes between the CS and the UCS, then it is less likely that the events will be linked together. This means that, in general, the closer time interval between the two stimuli's, the greater chance that a classical conditioning link will occur.

The strength of a stimulus is also a factor on conditioning a particular response. It was shown that cats given various tone-strong intensities developed different responses [1]. Cats that sustained a strong developed reliable flexion and heart rate responses to the stimulus, while the tone-weak cats didn't develop these reflexes.

For classical conditioning to develop, an incident needs to be of sufficiently high frequency to acquire the CR/UCR relationship. If the interval between incidents is too great, the connection is likely to be forgotten.

Another interesting phenomenon that Pavlov identified was a phenomenon that's come to be known as spontaneous recovery. This is the re-occurrence of a classically conditioned response after extinction has occurred. Extinction refers to the fact, that, if the conditioned and unconditioned stimuli are not paired for a given number of trials an organism will stop exhibiting the conditioned response. For example, if the dogs mentioned above don't receive any food with the stimuli, then the development of saliva would eventually not be caused by the sound of the chime (extinction). Since the dogs will not completely return to their unconditioned state, they can redevelop the association after a single repetition of the link between the chime and then food being presented.

Stimulus discrimination is displaying, or needing to display, different behaviour for certain situations. For instance, you might tell an oscine joke at a party with friends, but you wouldn't tell the same joke to a priest. The association between what is or not appropriate, will be learnt through positive or negative reinforcement in given situations.

Stimulus generalisation occurs when different situations produce the same response. This generalisation can be inappropriate, which occurs when those different situations fail to produce discriminative responses. Generalisation is not always inappropriate and occurs when you respond the same to two stimuli that are not identical. An example of this would be a child learns that a picture of a Rottweiler is a dog, while later associating that a Labrador is also a dog. This shows that the child has generalised between two distinct stimuli.

Operant Conditioning is a term that describes the consequences of a particular behaviour on the future possibility of that behaviour continuing. There are four types of Operant Conditioning: Positive Reinforcement, Negative Reinforcement, Punishment and Response Cost. Both Positive and Negative Reinforcement strengthen behaviour while both Punishment and Extinction weaken behaviour.

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