Eye–hand span

The eye–hand span is the distance across part of a text, usually a linguistic text that is being copied via typing or a piece of notated music that is being performed, defined as the distance between the position of the eyes acquiring that information and the hand(s) typing or performing it.[1] Specifically, the eye–hand span is typically measured from the location of central visual input, and stretches between the syllable or chord currently being typed or performed, and the lateral location of the simultaneous fixation. This distance may be measured either in units of linear measurement or in characters or other "bits" of data. Some authors refer to the eye–hand span as the "perceptual span" for the visual information perceivable around the region of center of vision used in reading,[2] and in some cases including peripheral input.[3] The eye–hand span is analogous to the eye–voice span in reading language aloud and in singing.

Astigmatism

Astigmatism is a widespread vision condition that can cause people to have blurred vision. It's caused by an imperfection in the cornea or lens of the eyes. Corneal astigmatism is when the cornea isn't evenly curved and smooth. Lenticular astigmatism is when the shape of the lens is distorted. Both conditions can be corrected by using toric contact lenses.[4]

See also

References
  1. Land, Michael F.; Tatler, Benjamin W. (2009). Looking and Acting. New York: Oxford University Press. p. 67. ISBN 978-0-19-857094-3.
  2. Keith Rayner (2012). Eye Movements in Reading: Perceptual and Language Processes. Elsevier. p. 81. ISBN 978-0-323-14628-9.
  3. Rayner, Keith; Pollatsek, Alexander (1997). "Eye Movements, the Eye-Hand Span, and the Perceptual Span during Sight-Reading of Music". Current Directions in Psychological Science. 6 (2): 49–53 [p. 49]. doi:10.1111/1467-8721.ep11512647. JSTOR 20182443.
  4. "Astigmatism". Misaki. Retrieved 2020-01-19.


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