Poltergeist is a German word for noisy spirit.
The biggest difference between a ghost and a poltergeist is the fact that a poltergeist, in general, attach to a person and not a place. Where this person - or Epicenter - is or goes the activities of the poltergeist follow. Typical for the poltergeist phenomenon is the fact that they often have something to do with a young person usually a woman, troubled by stress.

Andrew Green, paranormal researcher, is convinced that poltergeist activities are examples of Psychokinetics, (the moving of objects and the cause of sounds by will of mind, without touching the object physically).
He claims that this is created unconsciously by people of both sexes, between the ages of 3 and 40 years, usually caused by a psychical trauma.
This opinion is shared by American psychologist, William G. Roll, who discovered that of 92 cases in which there was an poltergeist concentrated on a person, 4 of these so called epicenters, suffered of epilepsy. Green acreas that in some poltergeist cases it could be the result of temporary epilepsy.
Someone who has this disease can have a blackout from a minute up to half an hour. During this temporary unconciousness, a particular force is created/set free, this force is the cause of RSPK, (Returning of Spontaneous PsychoKinetic.) But only a small percentage of the cases have epilepsy as a cause.
Green also discovered, from his own research, a possible connection with schizophrenia.

Andrew Green thinks that poltergeist activities are produced unconsciously and that they are an expression of a creative force that people can summon in themselves to deal with their suppressed feelings and emotional conflicts.