Its hard to tell which is why you need to keep a level head. I have never done automatic writing but I have worked with spirits, when they speak to you it sounds like someone is standing in the room with you having a conversation, not a voice in your head, it won't sound like your voice. When you channel a spirit with a pendulum, Ouija board, or automatic writing, you should be able to sense them, perhaps feel them touch you.
With automatic writing, you don't really do q and a, its more allowing the being to speak through you. You should cast a circle to create a 'holy ground' so to speak, then go into a deep meditation, almost trance like, at which point the spirit is suppose to move the pen in your hand to write words, hopefully coherent ones. This could be disproven a number of ways so take a leap of faith.