 On this view, what’s missing in ignorance cases isn’t a belief, but a belief-state. When Perry realizes what’s happening in the supermarket, he doesn’t (at least, he needn’t) come to believe any new propositions, but he does come to be in a new belief-state. He comes to be in the “I am the messy shopper” state, and thereby believes the proposition that Perry is the messy shopper. (He may have already had a belief with that content, but if so it will have been in virtue of being in a different belief-state.) It’s a change in belief-state, not just a change (if any) in propositions believed, that’s responsible for Perry’s changed behavior.