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2 Definition of Needs and Statement of Requirements
Pages 13-28

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From page 13...
... The lack of distinctive visual features and the total absence of nonvisual features for the common user constitute a hindrance to commerce and daily living for millions of visually disabled people. In addition, the lack of distinctive features results in problems of denomination for a much wider population with mild visual impairments, including those impairments acquired during the normal aging process, and for anyone in a poorly lit environment.
From page 14...
... According to these data, there are approximately 3.7 visually disabled Americans. The leading causes of low vision and blindness are diseases that are common in old age: age-related maculopathy, cataract, glaucoma, diabetic retinopathy, and optic nerve atrophy.
From page 15...
... b Low vision. for this table is defined as corrected visual acuity of no better than 20/70 in the better eye or a maximum diameter of visual field of no more than 30 degrees.
From page 16...
... experience difficulty recognizing the large digits on present banknotes in a common cash transaction. It should be noted that clinical definitions of acuity are based on controlled tests conducted under ideal viewing conditions bold black letters on a pure white background (near 100 percent contrast)
From page 17...
... afflicts many older people and is the leading cause of low vision. Because vision is lost in the high-resolution central portion of the visual field, afflicted individuals must rely on sight in their low-resolution peripheral vision.
From page 18...
... Source: The Jewish Guild for the Blind, 1992. Currency Features for Visually Impaired People alphanumeric symbols usually has little effect on recognition for people with normal vision.
From page 19...
... Definition of Needs and Statement of Requirements 19 a More important than polarity is the overall contrast level. Photometric measurements by a member of the committee of the contrast of the large corner digits on the portrait side of $1
From page 20...
... , the suboptimal contrast will also take its toll on recognition by normally sighted people. In addition to the 3.7 million visually disabled Americans, there are many people with mild visual impairment due to peripheral field deficits, glare sensitivity, or losses in contrast sensitivity.
From page 21...
... Daily activities include using currency in many situations, such as purchasing groceries and using public transportation. Significant experience and insight comes from visually disabled workers who operate cafeterias or vending stands, usually in governmene-owned buildings, under the Randolph Sheppard Act Business Enterprises Program.
From page 22...
... DISCRIMINATION VERSUS ABSOLUTE JUDGMENT This chapter has focused on the difficulties encountered by visually disabled people in currency identification. The design of new visual, tactile, or other features for banknote identification should take into consideration perceptual limitations on discrimination and absolute judgment that limit performance by everyone.
From page 23...
... or between a bill and a measuring gauge. A second kind of perceptual judgment, called absolute judgment, may be more important to currency identification.
From page 24...
... EXISTING CURRENCY DENOMINATION TECHNIQUES Many visually disabled people must trust others to inform them about the denomination of bills received. Once identified, these bills must be sorted for accurate retrieval later.
From page 25...
... that can be used by visually disabled people to denominate banknotes include the use of bills of varying sizes and colors. The use of varying sizes reportedly allows a blind individual to denominate bills accurately using a simple, inexpensive plastic guide.
From page 26...
... In addition, due to the increasing number of older individuals with impaired vision due to minor eye disease or the normal aging process, such features would be of great benefit to a far wider population than that represented by the current statistics on blindness and low vision. Certain new features, such as color and size, and enhanced existing features, such as larger numerals of higher contrast, would also benefit those with normal vision by making denomination more rapid and convenient for all.
From page 27...
... 1990. Blindness and visual impairment in an American urban population: The Baltimore eye survey.


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