Seeing light and color. The eye is often compared to a camera. It has a lens that produces an inverted image on the retina, whose surface is sensitive to light just as film is. In front, the eye has an iris that changes the size of the pupil, performing the same function as the diaphragm of a camera. The pupil is simply the hole in the iris through which light enters the eye. As its size changes, the pupil admits more or less light as needed, depending on the amount of illumination present. This adaptation by the iris to the level of illumination is continued by the retina . . . . A ray of light entering the eye passes through the transparent cornea, the aqueous humor, the lens, and the vitreous humor. All help focus the light before it strikes the rods and cones, which are photoreceptors located on the retina. Here is where the actual process of seeing begins. The greatest bending of light rays occurs at the first surface of the cornea.
A group of ligaments and muscles automatically control the shape of the lens to bring objects at different distances into focus on the retina. This process is called accommodation. As one gets older, the lens gradually loses it flexibility, and the ability to accommodate decreases. [p. 84]
[Light and Color, by Clarence Rainwater, Prof. of Physics, San Francisco State College, Original Project Editor Herbert S. Zim, Golden Press, NY, Western Publishing Company, Inc., 1971.]
Accommodation, a monocular cue for depth perception. The lens in each eye must bend or bulge to focus nearby objects. Sensations from muscles attached to the lens are channeled back to the brain. Differences in these sensations help us judge distances within about 4 feet of the eyes. Beyond 4 feet, accommodation has a limited effect on depth perception.
[Coon, Dennis. Introduction to Psychology, Exploration and Application. St. Paul: West Publishing Company, 1989 - Chapter on Perceiving]
R E F E R E N C E S
Accommodate vt [15550] 1: to make fit, suitable, or congruous 2: to bring into agreement or concord: Reconcile 3: to provide with something desired, needed, or suited [as a helpful service, a loan, or lodgings] 4a: to make room for b: to hold without crowding or inconvenience 5: to give consideration to: allow for [__ the special interests of various groups] -vi: to adapt oneself: also: to undergo visual accommodation
syn- see Adapt, Contain
Accommodation n [L accommodatus, pp. of accommodare, fr.ad- + commaodare to make fit, fr. commodus suitable -more at Commode] [1603] 1: something supplied for convenience or to satisfy a need: as a: lodging, food, and services or traveling space and related services -usu. used in pl. [tourist __s on the boat] [overnight __s] b: a public conveyance [as a train] that stops at all or nearly all points c: Loan 2: the act of accommodating: the state of being accommodated: as a: the providing of what is needed or desired for convenience b: Adaptation, Adjustment c: a reconciliation of differences: Settlement d: the automatic adjustment of the eye for seeing at different distances effected chiefly by changes in the convexity of the crystalline lens; also: the range over which such adjustment is possible
[Merriam-Webster's Collegiate Dictionary, 10th Edition. Springfield, MA, USA: Merriam-Webster, Inc. 1995.]
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