In psychoanalysis, there is a concept called an introject, …

In psychoanalysis, there is a concept called an introject, which means another person's voice that plays in your mind as if it was the other person. That is what the guide has become. "I HATE BASEBALL!" screams Stanley, knocking the guide back with his voice, which is formerly what the guide did to him. This suggests that it is really the guide speaking through Stanley. We know he does not really hate baseball.