The ideomotor effect may explain why people have occurances. I've tried using it myself to contact 'good' spirits. Maybe i need friends or two people whatever. I'm probably gonna ask for a demon/devil(whatever you believe) itself one day if i never get a response
like last time. There are usually psychological reasonings to many phenomenons. Infact there isn't a scientific grounding, peer-reviewed paper published to prove the existence of ghosts. We can have instruments to detect everything except for dark matter/dark energy (maybe they exist there?). Don't expect anything to happen, and don't expect the best to happen either, Goodluck on your quest.
-sincerely,
Aztec_king