There is an interplay between the processing of stimulus and the signals being transmitted from receptors in the eye to the visual cortex of the brain. Given that everyone thinks differently according to what they have experienced in life, this interplay between eye and brain creates room for subjective perception that changes from person to person. Things that are known to be subjective in visual perception include contrast, colour, contours, texture, 3D space, movement and orientation. These are processed and impacted by our experiences of the world to date.
" It seems difficult to deny that perception, at least in part, is influenced and determined by knowledge and concepts that we have developed through experience. It is as if the mature nervous system has acquired a hypothesis about 'what is out there'." Arne VALBERG . 2005