I was thinking that, this is just an idea of course but, I have been remembering the occasions when there were apparitions on some places(like my house), but while that period of time, the family or social group inhabiting the place were having conflicts, so I think that maybe that energy from discussions and negative thoughts, etc, were creating those supposedly paranormal events. I got on pdf those books Laura recommend on her interview about paranormal things. But could this be possible? because I can't find a real reason on a random apparition or event trying to scare you, there is no real sense, I mean, it's not like a ghost asking for a release or help, it's like some kind of psychich event, but a particular characteristic I've seen is that there's always stress and conflicts running over the place, or over the person seeing ghosts or having paranormal experiences.