Vision span or perceptual span is the angular span (vertically and horizontally), within which the human eye has sharp enough vision to read text. The visual field of the human eye spans approximately 120 degrees of arc. However, most of that arc is peripheral vision. The human eye has much greater resolution in the macula, where there is a higher density of cone cells. The field of view that is observed with sufficient resolution to read text typically spans about 6 degrees of arc, which is wide enough to allow a clear view of about five words in a row when printed text at ordinary size is held about 50 centimeters from the eyes. The brain creates the illusion of having a greater visual span by automatically and unconsciously moving the center of vision into any area of interest in the field of view.
Read more about Vision Span: Application To Speed Reading
Famous quotes containing the words vision and/or span:
“To stroll is a science, it is the gastronomy of the eye. To walk is to vegetate, to stroll is to live.... To stroll is to enjoy, it is to assume a mind-set, it is to admire the sublime pictures of unhappiness, of love, of joy, of graceful or grotesque portraits; it is to plunge one’s vision to the depths of a thousand existences: young, it is to desire everything; old, it is to live the life of the young, to marry their passions.”
—Honoré De Balzac (1799–1850)
“To course that span of consciousness thou’st named
The Open Road—thy vision is reclaimed!
What heritage thou’st signalled to our hands!”
—Hart Crane (1899–1932)