Full Idea
Rats and monkeys exhibit 'latent learning' (learning just for fun) which is later beneficial. They learn with no consequences, and then can't learn when the good consequences are available.
Gist of Idea
Animal learning is separate from their behaviour
Source
Georges Rey (Contemporary Philosophy of Mind [1997], 4.1.1)
Book Reference
Rey,Georges: 'Contemporary Philosophy of Mind' [Blackwell 1997], p.99
A Reaction
This looks like a bit of a setback for naturalised epistemology and cognitive science, if learning can't be brought within a stimulus-response framework.