I believe more in this specific theory over any other one I've read. The only remaining "what" is when figures, life-forms and such appear.
The main reason is when these particals appear and one person or life-form is on ones mind. Therefore... you'd get Grandpa sitting in the chair in
the corner.
However, there are those who do not expect such an occurance... or when the particals do not appear at the time of which one sees the figure, or
object.

