Apparitions of the Living: Also called bilocation, apparitions can be either spontaneous or intentional. In the case of spontaneous bilocation, the person whose apparition is seen is generally (though not always) unaware of his/her bilocation. Bilocation is considered intentional when the apparition can be connected to a person who was aware s/he was having an out of body experience (OBE), or with someone who was consciously trying to communicate with the person who witnessed his/her apparition.
Apparitions from another Dimension or Time: There are reports of apparitions who act as frightened of us as we are of them. In some cases, the apparitions indicate that we, not they are the ghosts. In reports such as these, the observed "ghosts" appear to be "normal" and "alive" as we know it, (although the setting and dress may be of a different era or locale). Given our incomplete understanding of time and space and the likelihood of additional dimensions, perhaps these rare reports indicate that two distinct spatial or time dimensions can somehow merge and coexist for a time.
Pseudo-Apparitions: Two other phenomena produce "ghosts" or apparition-like phenomena that are often confused with true apparitions. These are haunting apparitions and poltergeist phenomena. Haunting apparitions, at first glance, may appear very similar to apparitions of the dead. However, upon observation it becomes clear that they don not seem to possess intelligence or personality. Whereas a haunting, and the "images" seen or "sounds" heard," are repetitious "replays" of a past event that was somehow "recorded" by the environment of the location where it occurred, true apparitions allow for interaction, for two way communication, and display self awareness. The haunting apparition appears to be part of the event "recording"and communication or interaction with such a ghost is impossible (just as communication or interaction with a character you watch on TV is impossible while you're watching). Poltergeist phenomena involve physical disturbances caused by a living person (the poltergeist agent). The agent, due to unresolved emotional/psychological stresses, unconsciously uses a form of psychokinesis (mind over matter) to cause the physical disturbances. In rare poltergeist cases, apparitions may be seen or heard. These apparitions are believed to be an unconscious telepathic projection from the mind of the agent that is "picked up" by some
participants. These apparent mental projections of the agent do not display independent intelligence or personality. Often, such apparitions do not look human, but rather appear to be an archetypal reflection of the inner stress of the agent.
Witnessing an Apparition: Though most commonly seen or sensed (as in "sensing a presence"), apparitions are also reported to be heard, touched and smelled. When seen, they usually look solid to the touch, although they are sometimes reported as slightly transparent or with blurred edges. They may also be monochromatic or incomplete (visible only from the waist up, etc.). Often, the apparitions appears so lifelike that, unless the apparition is known to be dead, there may be no indication that s/he is a ghost until s/he vanishes. Typifying the person when previously alive, the apparition can change his/he age, style of dress, and emotional mood in a way that seems to relate to the self-image the apparition desires to project (i.e. when asked to mentally picture ourselves, we all tend to do so fully clothed). Not everyone present in a given location may perceive the apparition. This may be due to the sensitivity of the witness, the intent of the apparition, or a combination of both factors. Keep in mind that since perception involves both the physical senses and information processing by the mind/brain, what is "seen" or "heard" may not have a truly physical external form (and thus couldn't be photographed or recorded by technology). When more than one person sees the apparition simultaneously, the different angles at which the apparition is observed are such that the apparition seems to be physically present, "correctly" occupying three-dimensional space. Apparitions appear to be capable of using the full range of their own psychic abilities. Thus, because they have no physical speech apparatus, they communicate via telepathy. On rare occasion, apparitions have been known to interact with the physical environment (via psychokinesis).
Theoretical Explanations: If psi is our normal ability to communicate and interact with the environment in a way that is beyond our normal senses and muscles, then perhaps this psi ability can exist independently of our brains and bodies as a function of "higher intelligence,"consciousness, soul, etc. Using this concept, someone whose body has died (or who is literally out of his/her body) could still be capable of communication or environmental interaction through psychic abilities. Thus, an apparition could send a telepathic message that, if received, would cause us to"see" his/her form, "hear" his/her words, "feel" his/her touch, "smell" his her cologne or scent, etc. However, these "sensations" are, again, purely of the mental or psychic. They are transmitted by one mind and received by another. They are not physical in the sense that a person's body stands before you and speaks. As such, they do not reflect light or create sound waves and thus cannot be photographed or recorded. In the same way that people use psychokinesis (PK) to do move objects mentally, so could the apparition theoretically use PK to do the same thing --- although reports of such occurrences with apparitions are rare). The movement of objects, if performed via PK, could be photographed (this in contrast with a telepathic hallucination of something moving, which could not be captured on film). Several alternative models of understanding have been proposed. Some suggest that apparitions have nothing to do with dead people or "consciousness outside a body," but are the result of telepathic transmissions and PK by living brains (those in their bodies). Others propose that apparitions are subjective mental images triggered by psychological stress or by geomagnetic or other environmental influences. While the parapsychological model/definition of an apparition is a consciousness without a body, these other models do account for a number of specific cases and should be considered by investigators in all cases before conclusions are reached. In addition, cases often include a variety of factors and models overlapping.
Understanding Apparitional Experiences: Regardless of theoretical model, apparitions seem to involve the manifestation of some form of human consciousness (whether the "ghost" is truly an outside consciousness or whether it is an hallucination generated by the viewer's brain, remains to be seen). Because some form of human consciousness is involved, communication with apparitions is possible. The apparition is often there for a reason that can be learned simply by asking. By directly addressing the apparition, the needs of both the apparition and the witness can be exchanged, opening the way for a solution that works for both participants. This type of diplomatic problem solving is typically very effective, but the fear, confusion and shock that most people experience in the presence of an apparition may make it difficult to ask the apparition questions. This seems to be related to a universal fear of the unknown, because apparitions,
with extremely rare exception, have not been known to harm people. Of course, people have been injured, physically in their attempts to exit the scene at superhuman speed, and psychologically in their fear-ridden expectations of what could happen. During a case investigation of an apparition, witnesses are taught the current understanding of apparitions and learn how to control/transform their fears. Because of the personal nature of most apparitional visits, the witness is usually the only person who will ever experience the apparition. Thus, in the case of subsequent visits, it is generally his/her responsibility to address the "entity" if resolution is desired. Counseling is always recommended to people experiencing an apparition in order to integrate the experience, and specifically the fear and confusion, in a healthy manner.
* Information from the American Institute of Parapsychology