Persistence of vision is the optical illusion
accounting for the perception of reality;
occurring when visual perception of an object
does not cease after the light rays proceeding
from it have ceased to enter the physical eye;
                   The effect has also been described as  
                   "retinal persistence",
      "persistence of impressions",
  or simply "persistence" or "impressions"      among other variations;

This had          once                      
          been believed to be the explanation
                        for motion perception in cinema
                        and animated films,
but this notion has been discarded by scientists;
It is assumed that the illusion
that film historians often refer
to as "persistence of vision"
is the same as what is known
                 as positive afterimages or memory                 by psychologists;
The cause of positive afterimages
[imagination of the senses]
                       is not known,
reflecting persisting activity in the brain
when the retinal photoreceptor cells continue
to send neural impulses to the occipital lobe;

in early preneurophysics,  descriptions of the effect
often attribute it purely to imperfections of the eye,
particularly of the retina;
       Nerves and parts of the brain only
later becoming part of explanations;

Sense memory has been also cited as a cause