Suzanne,
Kanzi "knew" he did something wrong and finally apologized, and Steve(?) could communicate with him. The whole story, is really about the "language" that the 3 of them created and used. Not a keyboard or sign, but vocal, which ALL 3 could understand. Kanzi "told" Steve that he needed to protect the woman and if he didn't, Kanzi would punish Steve, by biting him, which he did the first time later, that Kanzi had an opportunity. That's communication!
This is a first, as far as I can see, where a human and an Ape, communicate orally and understand each other!
Rich