Skeptical parapsychologists don’t deny that the phenomena themselves are real. They just deny that they are caused by discarnate spirits. Since poltergeist phenomena follow a particular person rather than remaining in a particular place, it is easy to blame the person rather than a reputed spirit.
When skeptical parapsychologists investigate a haunting and see an empty vase levitate off a bureau top and then go flying across the room unassisted by human hands (or an earthquake), they attribute that event to psychokinesis manifested by the living poltergeist agent, most often an adolescent child. This is their definition of a poltergeist.
As I mentioned above, some people have natural psychokinetic abilities. This is especially true during their adolescent years when their sex hormones are raging. Objects fly around the room, vases topple over, all sorts of noises sound all over the place. In some of these cases, the skeptical parapsychologist is correct, and there is no spiritual agent involved. It’s just natural human psychokinesis. Chances are that if you search through the family genealogy, you will find other members who had similar experiences growing up. This facility, along with other psychic abilities seems to run in families.
Skeptical parapsychologists see no need to invoke what they see as an imaginary spirit independent of the agent. To them, there is just an unruly child who is angry and wants to break the vase but can’t be seen doing it because he or she would be punished for such an overt act. Instead, the child subconsciously directs his or her anger outward, causing it to manifest as psychokinetic violence directed against the vase instead of the parents. That way the child doesn’t get blamed. The skeptical parapsychological view is that there is no dead guy; only a naughty kid, and it was her intention, and hers alone to use her psychokinetic energy to break the vase!
Parapsychologists have pointed out that most of these disturbances happen around adolescents who are undergoing puberty, and that if the disturbances are ignored, they tend to disappear by themselves after a few months. They attribute this to a rapid maturation on the part of the child who simply outgrows the need to psychically “show off”.
However, in many instances it can be exceedingly difficult to deny that an alien intelligence is involved, especially if the phenomena are violent and a demonic entity is suspected of involvement. The real-life events upon which the movie “The Exorcist” was based was such a case. (See Possessed: The True Story of an Exorcism by Thomas B. Allen).