With whom does Lennie have his imaginary conversations, and why does Lennie needs to imagine these people?

After killing his puppy and Curley's wife, Lennie knows he has done something extremely bad. He runs to the place George had told him to go if he got in trouble, again. Sitting by a clearing near the Salinas River, Lennie is extremely agitated and he is waiting for George. At this one time in the novel, he is really all by himself. He begins to hallucinate first about his dead Aunt. As he talks to her imaginary image, she scolds him in the same way George would scold him. She says, "All the time he[George] coulda had such a good time if it wasn't for you." Lennie is using the vision of his aunt as a way for his conscience to communicate with him. When the aunt disappears, a giant rabbit tells him "You ain't fit to lick the boots of no rabbit." Again the vision is reminding Lennie of all the things George had told him. This is Lennie's way of dealing with his behavior. He does not quite comprehend the seriousness of actions, but the visions are authority figures who talk to him just like George because, at this point, facing George himself is almost impossible.