Experience Your Blind Spot
Close one eye. Fix your gaze on either the top or bottom "X". View from a distance of about 80cm. Gradually move toward the screen while keeping your gaze fixed on the X. The eye pictured on the same side as the eye that you are using is the one that will disappear as you move toward the screen. The disappearance will occur when you are gazing from about 45 cm. and the projection falls on your blindspot. Hold your viewing distance constant and glance at the object that disappeared. You will see it when you look at it, but will not see it when the projection from it falls on your blindspot. The top figure works well on high resolution monitors and the bottom figure works best for low resolution monitors.
Each of our eyes has a region in which there are no receptors (rods or cones). This region is where the retinal ganglia exit the eye as the optic nerve. Our visual experiences do not typically include an awareness of the blind spots that result from the absence of rod and cone receptors in this region.
Can you devise an extension of this demonstration to map the blind spots of your eyes? You might want to look at the measurement of visual angles.
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