Abstract
The visual acuity of human eye is not uniform over the retina, but is almost only good at a narrow central portion called the fovea. This forces the eyes to move around to acquire the information of the outside world. Indeed the eyes move very rapidly and continuously so that the fovea covers the entire field of the outside. We may ask then that a wide visual field may be unnecessary to perceive figures and to read letters as long as the eyes can use the fovea and can move at will. An artificially limited visual field was imposed to a subject while he/she reads sentences or looks at a figure. It was found that if the field became too narrow the pattern recognition became impossible to imply that a certain size of the visual field is indeed needed for the eyes to carry out their task of pattern perception. The difference between the outside world and the retinal image was also discussed, the former being 3D while the latter 2D. The brain has to recover the dimensionality to perceive the outside world rightly. It was pointed out that we experience the recovery in the phenomenon called size constancy.
