Structure-mapping theory aims to improve upon previous theories of analogy, by distinguishing analogy from literal similarity. Previous theories, like Amos Tversky's contrast theory, assumed that an analogy is stronger, the more attributes the base and target have in common. Instead, structure-mapping theory recognizes that there can be differences between base and target domains which make no difference to the strength of the analogy. For example, we can see a battery as being like a reservoir despite them being different in shape, size, color and substance.
