Vision span
Encyclopedia
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 cell
s. 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.
and skimmers. Speed readers cannot answer questions about a main point or detail, if they did not fixate directly on it or within three character spaces of it (Just and Carpenter 1987). When a text is removed whilst reading, readers can only accurately report upon the word they were fixating upon or the next one to the right (McConkie and Hogaoam 1985). There is no evidence from eye movement research that individuals are making predictions of text based upon hypotheses about the words in the periphery so that they can skip over or spend less time on unimportant or redundant words (Rayner, 1975).
Most speed reading courses claim that the peripheral vision can be used to read text. This claim has been found to be false, because the text is blurred out through lack of visual resolution. At best the human brain can only guess at the content of text outside the macular region. There simply are not enough cone cells away from the center of the visual field to identify words in the periphery of the field.
It has been suggested, primarily through popular psychology
, that the fixation span can be stretched through training (meta guiding) to take in as much as a line for the purpose of skimming or speed reading. This suggestion has been found to be false, which goes some way to explain why skimming results in a severely reduced comprehension rate in comparison to normal reading ("rauding").
Some speed reading courses stress that the human eye has to move very quickly. They also stress that the human eye should move in a pattern to fill in the information that was not properly perceived. The effective limit for scanning speeds based upon the limit of the human eye's resolution is approximately 10,000 words per minute . It is claimed that such speeds also require great practice, and extremely rapid eye movements, although research suggests that such training is not possible. It has been suggested by some speed reading promoters that the readers who achieve such speeds are on the autism spectrum
. Research into reading rate suggests that study strategies, rather than speed reading, explains why expert readers, such as professors and editors, are more efficient than others.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
has sharp enough vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
to read text. The visual field
Visual field
The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments", while 'field of view' "refers to the physical...
of the human eye spans approximately 120 degrees of arc
Degree (angle)
A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
. However, most of that arc is peripheral vision
Peripheral vision
Peripheral vision is a part of vision that occurs outside the very center of gaze. There is a broad set of non-central points in the field of view that is included in the notion of peripheral vision...
. The human eye has much greater resolution
Optical resolution
Optical resolution describes the ability of an imaging system to resolve detail in the object that is being imaged.An imaging system may have many individual components including a lens and recording and display components...
in the macula
Macula
The macula or macula lutea is an oval-shaped highly pigmented yellow spot near the center of the retina of the human eye. It has a diameter of around 5 mm and is often histologically defined as having two or more layers of ganglion cells...
, where there is a higher density of cone cell
Cone cell
Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. If the retina is exposed to an intense visual stimulus, a negative afterimage will be...
s. The field of view
Field of view
The field of view is the extent of the observable world that is seen at any given moment....
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.
Application to speed reading
While reading, readers will fail to recognize a word unless they are fixating within three to four character spaces of the word (Rayner, 1975). The same is true for speed readersSpeed reading
Speed reading is a collection of reading methods which attempt to increase rates of reading without greatly reducing comprehension or retention. Methods include chunking and eliminating subvocalization...
and skimmers. Speed readers cannot answer questions about a main point or detail, if they did not fixate directly on it or within three character spaces of it (Just and Carpenter 1987). When a text is removed whilst reading, readers can only accurately report upon the word they were fixating upon or the next one to the right (McConkie and Hogaoam 1985). There is no evidence from eye movement research that individuals are making predictions of text based upon hypotheses about the words in the periphery so that they can skip over or spend less time on unimportant or redundant words (Rayner, 1975).
Most speed reading courses claim that the peripheral vision can be used to read text. This claim has been found to be false, because the text is blurred out through lack of visual resolution. At best the human brain can only guess at the content of text outside the macular region. There simply are not enough cone cells away from the center of the visual field to identify words in the periphery of the field.
It has been suggested, primarily through popular psychology
Popular psychology
The term popular psychology refers to concepts and theories about human mental life and behavior that are purportedly based on psychology and that attain popularity among the general population...
, that the fixation span can be stretched through training (meta guiding) to take in as much as a line for the purpose of skimming or speed reading. This suggestion has been found to be false, which goes some way to explain why skimming results in a severely reduced comprehension rate in comparison to normal reading ("rauding").
Some speed reading courses stress that the human eye has to move very quickly. They also stress that the human eye should move in a pattern to fill in the information that was not properly perceived. The effective limit for scanning speeds based upon the limit of the human eye's resolution is approximately 10,000 words per minute . It is claimed that such speeds also require great practice, and extremely rapid eye movements, although research suggests that such training is not possible. It has been suggested by some speed reading promoters that the readers who achieve such speeds are on the autism spectrum
Autism spectrum
The term "autism spectrum" is often used to describe disorders that are currently classified as pervasive developmental disorders. Pervasive developmental disorders include autism, Asperger syndrome, Childhood disintegrative disorder, Rett syndrome and Pervasive Developmental Disorder Not Otherwise...
. Research into reading rate suggests that study strategies, rather than speed reading, explains why expert readers, such as professors and editors, are more efficient than others.