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CHAPTER 1
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INTRODUCTION
Color vision tests are used for a wide variety of purposes. Some of
these include the rapid screening of congenital red-green defects in
industry, transportation, and the military. The classification of
discrimination ability within the population of congenital red-green
defects is used for job assignment purposes. Another use for screening
involves the recognition and diagnosis of congenital disorders for
psychophysical or genetic study. In the the clinic, screening is used
for the recognition and differentiation of congenital and acquired
disorders, for the classification of acquired disorders in patients
with eye disease, and, in some cases, for the assessment of treatment
or for tracking recovery from disease or trauma. Finally, in education
and industry, screening for both color vision defects and color apti-
tudes is used for vocational guidance in occupations or professions
that require color judgments.
The two major problems faced by those who use color vision tests
are (1) to know the color vision requirements of a given task and (2)
to select appropriate color vision tests.
COLOR VISION REQUIREMENTS IN DIFFERENT OCCUPATIONS
it is essential for the benefit of both employer and employee that the
color vision requirements of a job be adequately described. On the
basis of these professional requirements and observer capabilities a
decision can be made about whether an individual's color vision is
suitable for performing the particular duties encountered in daily work
situations. Such practical assessment of the relevant color
qualifications helps to prevent the inappropriate allotment of
manpower. A major difficulty in this regard is the lack of precise
checklists of color vision requirements for different jobs; there are
no guidelines to help employers establish color requirements for a
given job. Broadly speaking, however, many occupations can be divided
into three categories (e.g., Lakowski, 1968) depending on the quality
of color vision required:
1. Those excluding major color defective observers;
2. Those requiring representative color vision ;
3. Those requiring good color discrimination.
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Occupations Excluding Major Color Vision Defects
There are many activities and occupations in which defective color
vision is either undesirable or unacceptable. Generally observers with
severe color defects should not be expected to work in any industrial
situation in which a premium is placed on the recognition and/or
classification of color surfaces, lights, or objects. Abnormal color
vision is therefore a serious handicap in all those areas of
electronics and telecommunications that involve the identification,
coding, and wiring of electrical equipment. The exclusion of major
color-defective observers is also essential in transportation
industries (railway, marine, or aviation) in which confusion of signal
lights can endanger public safety. On the other hand, not all
professions that validly exclude major color defective observers
require normal color vision. Individuals with mild impairments can
perform many operations involving color discrimination without any
special risk to their own or to public safety.
Occupations Requiring Representative Color Vision
There are a vast number of occupations in which the mere exclusion of
color-defective observers is an inappropriate policy for selecting
personnel. In industry, especially, it seems more important to
discover whether a person is fit for a particular job than to classify
him or her as either normal or color defective. What is required in
most situations is to establish whether the employee has the necessary
skill to deal with a particular color task or to satisfy some criteria
acceptable to the employer. In such areas as color research, commercial
painting, color photography, chemistry, papermaking, paint mixing, the
graphic arts, lithography, cartography, and textile dyeing, it is
especially important that those who must make color matches have color
vision that is representative of the majority of consumers. It is well
known that color-matching ability may vary considerably from one
observer to another; those observers who fall at the extremes of the
distribution of normals may be considered to have an atypical form of
normal color vision. Usually such deviations from the mean are not
diagnosed by routine testing, yet they may constitute serious practical
color vision problems by reducing the individual's effective job
performance.
Occupations Requiring Good Color Discrimination
In many professions, individuals are chosen for their ability to make
fine or difficult decisions in color discrimination. Here the exclusion
of color-defective observers is not the prime consideration. Rather,
people are selectively chosen for their precision in matching sample
colors to standards or in classifying colors that differ only very
subtly. In addition, in some occupations the recognition of color at
twilight levels of illumination is required. Only individuals with
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good color discrimination or specific aptitudes can perform these types
of jobs with facility and accuracy.
SELECTING COLOR VISION TESTS
It is possible to design appropriate task-specific field tests in order
to establish the color vision requirements of different jobs, but such
a job-by-job analysis would be inefficient and expensive. On the other
hand, selecting an available clinical color vision test for a particular
application is not simple. First, information concerning the merits of
these tests relative to each other and to various job requirements has
not been readily available. Second, clinical color vision tests are
not designed for the scaling of performance or for multiple cutoff
criteria; the scoring standard for most clinical tests is stated in
terms of a single pass/fail score. Third, the classification of color
discrimination ability by clinical tests might not predict performance
in a real-life situation (Kinney et al., 1979~. Many experts feel that
to generalize from a clinical test to a job requirement is inappropriate
at best and meaningless at worst. Fourth, the determinants of perform-
ance on each test are sufficiently complex, ranging from calorimetric
design to motivational factors, that no test can be considered to
provide a single metric of color vision.
In the absence of good population studies that relate job perform-
ance measures to test scores in batteries of color vision tests, these
problems might be essentially insolvable. However, an understanding of
the existing color vision tests may help an employer who is familiar
with the job requirements to decide whether to use a clinical test or
to have field tests designed to his specifications. This report
surveys the existing clinical tests of color vision and gives some
general indications as to their design and use.
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Representative terms from entire chapter:
vision tests
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