A negative afterimage is the phenomenon where exposure to a visual stimulus leads to an afterimage of opposite polarity (e.g. perceiving an illusory black spot after exposure to a white spot). Such afterimages are normal, and are believed to arise at the level of the retina [e.g. [14]].

What does it mean if I always see negative afterimages?

Negative afterimages occur when the rods and cones, which are part of the retina, are overstimulated and become desensitized. This desensitization is strongest for cells viewing the brightest part of the image, but is weakest for those viewing the darkest.

How much after image is normal?

The afterimage may remain for 30 seconds or longer. The apparent size of the afterimage depends not only on the size of the image on your retina but also on how far away you perceive the image to be.