'Generalisation'
'Generalisation' is the process by which a specific conditioned stimuli (CS), may be generalised to any stimuli that is similar to the original stimuli. For example, in Pavlovs experiments a tone was used as the 'conditional stimulus' (CS). It was found that tones of a similar frequency would elicit the same response as the CS (salivation).
'Discrimination'
'Discrimination' put simply, occurs when an animal learns to recognise the difference between different stimuli. Take for example, a tone of a set frequency being used to elicit salivation in dogs (as in Pavlovs experiments). If another tone is used to signal that the dog was to recieve an electric shock, we would find that the dog would learn to 'discriminate' between the two tones of freqency.
NB - Personally, I believe that human beings are exposed to the same kind of treatment in complex societies, and maybe something as simple as discrimination may be resposible for the high stress levels we all face in day to day life.
This phenomena has practical significance, in that human beings are required to recognise stimuli as holding the same value, despite their changed appearance. For example, when a face is viewed from several angles, its visual qualities change. However as human beings, we are required to recognise that a person remains the same in identity, when they are viewed from different angles!
There is also the belief that some animals may not be able to perceptually detect the difference between stimuli, due to the limitations upon their sensory organs or their nueral coding for those organs. It is likely that both of these elements are in play when generalisation occurs.
This is of utmost importance to a human being when they must learn how to react to various perceptions.An example of both..
I once read of an experiment, in which a dog was shown a circle and given some food, which led to salivation. Then it was shown an oval, but was not given food. Initially the dog salivated at the sight of the oval, as it 'generalised' that the two stimuli were the same.
After repeated trials, the dog managed to 'discriminate' between ovals and circles, learning that a circle indicated the presence of food, while an oval did not.
As the trials went by, the experimenter gradually made the ovals more circular, in order to fine tune the dogs ability to discriminate between the two stimuli. The dog was able to perform an extraordinary ability to discriminate between the two, toward the end of the experiment. However the dog became highly nuerotic after many trials, for some unknown reason.