There are some realitvely new theories which are intened to explain a specific type of huanting which is known as a residual haunting. A
residual hautning is a haunting in which there is the same scene or image that continues over and over again and in which the spirit acitivity or so called ghost seems unware of itself and its surroundings and does not appear to have any interaction with its enviroment.
An example of a residual haunting might include cases in which people report seeing a woman, floating down a set of stairs and then just vannishing, and replaying this over and over again without change, or without appearing to be engaged in those around it or its setting.
The reason this type of haunting is called a residual haunting is becasue according to new theroy this is not a true huanting, but rather it is a memory that has been preserved and then projected.
There are studies being done that suggest crystals and certain type of simillar stones have the ability to record images and then replay them in a sort of loop which then creates the affect of the residual haunting.