Generalisation and discrimination are complementary processes in learning. Generalisation occurs due to similarity, where an organism responds similarly to similar stimuli. When a learned response is elicited by a new stimulus, it is called generalisation. In contrast, discrimination is a response due to difference.

For example, if a child conditioned to fear a person with a long moustache in black clothes later shows fear towards another person in black with a beard, this is generalisation. However, when the child meets a stranger in grey clothes who is clean-shaven and shows no fear, this demonstrates discrimination.

The occurrence of generalisation indicates failure of discrimination. Discriminative response depends on the discrimination capacity or discrimination learning of the organism.