piece continuously. The subject used his pre-
ferred eye.

Subjects who made matches outside the limits
of 38-44 on the instrument’s arbitrary scale of
0-73 were classified as defectives. Ranges less
than 10 were classified arbitrarly as mild defects,
ranges between 11 and 25 as moderate, and ranges
greater than 25 as severe. The anomaly was
classified as extreme for subjects whose range of
matches made with chromatic adaptation was
greater than the range obtained with “neutral”
adaptation. The direction of deviation of the
center of the range of matches from the normal
limits determined the diagnosis of type of de-
ficiency, i.e., subjects who required more green
than normal in their matches were classified as
deutan, while those using more red than normal
were protans. Dichromats, subjects who matched
the entire range of the instrument, were classified
as protanopes if the yellow luminance setting was
very low for matches with red and as deuter-
anopes if the yellow luminance was normal. For
the purpose of comparison with other tests, sub-
jects whose range of matches exceeded 10 units
were considered failing.

N.B. After many subjects in Group 1 had been
examined, it was discovered that the linkage be-
tween the comparison (yellow) slit and the mi-
crometer drum had become misaligned so that the
luminances of/ the yellow field were sharply
attenuated. This condition made it impossible
to distinguish clearly severe protanomalies from
protanopes. To facilitate comparisons the mis-
alignment was maintained for all subjects. The
spectral specifications were not affected by the
misalignment.

9. Each subject received a practical test of his
ability to recognize light flashes of aviation signal
red, white, and green. This test, which was
identical to the test administered by FAA Gen-
eral Aviation District Offices to airman candi-
dates who desire Statements of Demonstrated
Ability for the color vision requirement, was
given outdoors during daylight hours. An FAA
color signal light gun was stationed indoors at a
window at an elevation of 38 feet. The subject
was stationed at distances of 1000 and 1500 feet
from the window and at each distance three five-
second flashes were presented at two-minute in-

tervals, the flash colors being randomly selected
but with the proviso that all three colors be pre-
sented at least once within each six-flash test.
The subject was asked to identify the color of
each flash before the flash terminated. One or
more errors in identifying the colors of the six
flashes is a failing score.

The pass-fail criteria for the A.O. H-R-R
plates, the Dvorine plates, the Color Threshold
Tester, the Farnsworth Lantern, and the Titmus
Vision Tester Plate are criterion scores used by
Aviation Medical Examiners for candidates for
Class II and IIT medical certificates.t The pass-
fail criterion for the Farnsworth Panel D-15 is
the criterion suggested by Farnsworth? for in-
dustrial and military applications, although no
specific aviation criterion was suggested. The
pass-fail criterion for the Farnsworth-Munsell
100-hue test is taken from Farnsworth’s sugges-
tion that error scores exceeding 100 fall beyond
the range of normal competence for color dis-
crimination.’ The pass-fail criterion for the
anomaloscope was arbitrarily selected. No effort
was made, in the current study, to determine if
pass-fail criteria other than those employed in
the current study might produce improved cor-
relations between any of the tests studied and
the color signal light gun test.

Il. Results.

The ranges of anomaloscope matches made by
all subjects in Groups 1 and 2 are shown in
Figures 1 and 2. The ranges for normal, pro-
tanomalous, and protanopic subjects are shown
in Figure 1, while ranges for deuteranomalous
and deuteranopic subjects are shown in Figure 2.

The ranges obtained under chromatic adapta-
tion from subjects labeled extreme anomalies are
indicated by broken lines, while solid lines indi-
cate the matches obtained under “neutral” adap-
tation.

Table 1 indicates the product-moment correla-
tions (phi coefficients) between each clinical test
and the color signal light gun test for Group 1
subjects. All correlations represent significant
chi-squares at the 0.01 level. Examination of
Table 1 indicates the highest correlations were
obtained from the Color Threshold Tester and
from the Farnsworth Lantern.





reveals wide variation in miss rate with relatively
little variation in phi coefficients.

IV. Discussion.

Examination of Tables 1, 2, and 3 suggests
that the tests used in the current study may be
divided into four groups. The first group con-
sists of the A.O. H-R-R, the Color Theshold
Tester, and the Farnsworth Panel D-15—all tests
with very high miss rates. The number of
“misses” is important, from the standpoint of
safety, because these are the per cent of appli-
cants who will receive medical certificates with-

Tanve 2—Correlations between clinical tests and the
color signal light gun test.

Group 2

Phi Percent

Test Coefficient* “Misses”
A. 0. H-R-R- +48 14.1
Anomaloscope- BS 7.0
Color Threshold Tester--.... 38 8.5
Dvorine Plates - AAT 4.2
Farnsworth Lantern. - 45 4,2
Farnsworth 100-hue- _ 83 8.5
Farnsworth Panel D-15...... 54 11.3
Titmus Plate - BE 14

¥*All correlations are significant at the . 01 level.

out color vision restrictions, but who should re-
ceive certificates with restrictions, since they are
unable to discriminate among aviation signal
colors. For this reason, the tests in this group
appear to be unsatisfactory for screening airman
applicants.

The second group of tests consists of the anom-
aloscope, the Dvorine plates, and the Farnsworth-
Munsell 100-hue test—all tests with average cor-
relations and moderate miss rates. None of these
tests is an outstanding measure of color vision
requirements for aviation, but all have some
predictive value without the high miss rate asso-
ciated with the first group of tests.

Tasue 3.—Correlations between clinical tests and the
color signal light gun test.

Groups 1 and 2

Phi Percent

Test Coefiicient* “Misses”
A. 0. H-R-R. +50 14.1
Anomaloscope 4 5.6
Color Threshold Tester - 50 9.6
Dvorine Plates... - +50 6.6
Farnsworth Lantern. - +53 3.5
Farnsworth 100-hue. AT 6.6
Farnsworth Panel D-15_...-- 255 12.6

*All correlations are significant at the .01 level.

The remaining two tests stand alone. Based
on the data in Table 2, the Titmus Vision Tester
Plate appears to have a low predictive value.
This seemingly inferior performance is accom-
panied by the lowest per cent of “misses” en-
countered in the current study. That both the
Titmus phi coefficient and miss rate are low is
due to the high per cent of false positives (39.4%)
obtained with this test. The false positives are
those subjects who failed the Titmus Plate, but
passed the color signal light gun test. Thus a
relatively high number of applicants will fail
this test, when they should be passed. Airman
applicants who fail the color perception plate of
the Titmus Vision Tester should be given an op-
portunity to take another test for the color vision
requirement.

The Farnsworth Lantern consistently yielded
one of the highest correlations with the color
signal light gun test and, at the same time, con-
sistently yielded low miss rates. These data to-
gether with the Farnsworth Lantern’s high face
validity suggest that the Farnsworth Lantern
may be the preferred test for screening airman
applicants.

Examination of Figures 1 and 2 reveals that a
high proportion of the subject population were
dichromats or severe anomalies. Had a test
population with a higher number of mild and
moderate anomalies been used, the correlations
observed in this study would certainly have been
different.



130

131 7

132

iB

138-136 | Normal

137

138-140

141-142

1aa- 145

\ae- 147 — Borderline Defective -
138 Protanomalous
18st

152 i

182, | Mild Protanomalous
155

186

gS

139 7

160

161

162 - 164

165-166

169

170-172

173

178-177 | Severe Protanomalous
1ao-tee | or Protanopic
183

184

185-186

187-188

189

190

191 -

192 7

193

194

195 Extreme Protanomalous
196

197

198 -

ni
fe) 10 20 30 40 50 60

Ficure 1. Range of anomaloscope matches made by normal, protanomalous, and protanopic subjects under condi-
tions of “neutral” adaptation (solid lines) and, where different, chromatic adaptation (broken lines).

Tapix 1—Correlations between clinical tests and the
color signal light gun test.

Group 1

Phi Percent

Test, Coefficient* — ‘Misses’”
A. O. H-R-R___----------- 252 14,2
Anomaloscope. 44 4.7
Color Threshold Tester _ «58 10.2
Dvorine Plates... «52 7.9
Farnsworth Lantern_. 58 3.1
Farnsworth 100-hue_ 254 5.5
Farnsworth Panel D-15_ 54 13.4

¥*All correlations are significant at the .01 level.

Also shown in Table 1 are the percent of
“misses” for each test, ie, the percent of sub-
jects who passed the clinical test, but failed the
color signal light gun test. The highest miss

rates were obtained with the A.O. H-R-R, the
Farnsworth Panel D-15, and the Color Threshold
Tester. Wide variation in miss rate may be seen
for tests with similar phi coefficients.

Table 2 indicates the product-moment correla-
tion between each clinical test and the color sig-
nal light gun test and the per cent of “misses”
for subjects in Group 2. Again, all correlations
are significant at the 0.01 level.

This group was included so that the perform-
ance of the Titmus Vision Tester Plate could be
evaluated relative to the other tests. Table 2
indicates that the Titmus Plate has the second
lowest phi coefficient, but the lowest miss rate.

Table 3 indicates the correlations obtained
when Groups 1 and 2 are combined. As before,

the per cent of “misses” obtained with each test
are also shown. Again, inspection of Table 3


w

Pa

REFERENCES

. Federal Aviation Administration: Guide for Aviation

Medical Examiners. Department of ‘Transportation,
Federal Aviation Administration, Office of Aviation
Medicine, June 1970.

. Lewis, M. F., and F. K, Ashby: Diagnostic Tests of

Color Defective Vision. Annotated Bibliography,
1956-66, FAA Office of Aviation Medicine Report No.
AM 67-8, May 1967.

. Hardy, L. H., G. Rand, and M. C. Rittler: The H-R-R

Polychromatic Plates. I. A Test for the Detection,
Classification, and Estimation of the Degree of De-
fective Color Vision, A.M.A. ARCH, OPHTHAL,
51 :216-228, 1954.

. Hardy, L. H., G. Rand, and M. C. Rittler: The H-R-R

Polychromati¢ Plates. II. Comparison of Qualitative
Quantitative Classifications by H-R-R Plates and Other
‘Tests, A.M.A. ARCH. OPHTHAL., 52:353-368, 1954.

. Farnsworth, D.: The Farnsworth-Munsell 100-Hue and

Dichotomous ‘Tests for Color Vision, J. OPT. SOC.
AMER., 33 568-578, 1943.

6.

n

9%

2

. Rowland, I

Farnsworth, D.: Lhe Marnsworth-Munsell 100-Hue
Test for the FBaamination of Color Discrimination.
Manual, Baltimore, Munsell Color Company, 1957.

S.: Selection and Validation of Tests
for Color V i—Relationship between Degree of
Color Deficiency and Ability to Identify Signals from
a “Biscuit Gun.” School of Aviation Medicine Project
Report No. 187-7, November 1943.

. Farnsworth, D., and P, Foreman: Development and

‘Trial of the New London Navy Lantern as a Selec-
tion Test for Serviceable Color Vision. BuMed Proj-
ect X-457 (AV-241-K), Color Vision Report No. 12,
U.S. Submarine Base, New London, Connecticut,
6 May 1946,

. Farnsworth, D.: The Farnsworth Dichotomous Test

for Color Blindness. Manual, New York, Psycholog-

ical Corporation, 1947.



TECHNICAL REPORT STANDARD TITLE PAGE

~ Report No. 2. Government Accession No. 3. Recipient's Catalog No.

FAA-AM-71- 27

*

3. Report Date
June 1971

|. Title and Subtitle

COLOR DEFECTIVE VISION AND THE RECOGNITION
OF AVIATION COLOR SIGNAL LIGHT FLASHES

& Performing Organization Code

> Author!) 8. Performing Organization Report No.

Mark F. Lewis, Ph.D.
Jo Ann Steen, B. A,

. Performing Organization Name and Address 10. Work Unit No.

FAA Civil Aeromedical Institute

TT. Contract or Grant No.

P. 0. Box 25082
Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

. Sponsoring Agency Nome and Address
Office of Aviation Medicine
Federal Aviation Administration

OAM Report

800 Independence Aye., S.W. 14. Sponsoring Agency Code

Washington, D. C. 20590

. Supplementary Notes

This research was conducted under Tasks AM-B~69~PSY, AM-A-70-PSY~19, and
AMwA-71=PSY-19.

Abstract

Subjects of varying type and degree of color deficiency were tested on a battery
of color tests, including the American Optical H-R-R plates, the Dvorine plates,
the Color Threshold Tester, the Farnsworth Lantern, the Farnsworth-Munsell
100-hue, the Farnsworth Panel D-15, the Titmus Vision Tester Color Plate, and
an anomaloscope examination. Correlations with a practical test of the ability
of subjects to discriminate aviation signal red, white, and green were obtained.
The results generally indicated that the Farnsworth Lantern was a superior
predictor of performance on the practical test.

17. Key Words 18. Distribution Stotement

Color Vision
Signal Lights
Night Flight

Availability is unlimited.

22151, for sale to the public.

Document may
be released to the National Technical
Information Service, Springfield, Virginia

19. Security Classif, (of this report)

Unclassified

Bi. No. of Pages

7

20. Security Classif. (of this page)

Unclassified

22, Price

$3.00

Form DOT F 1700.7 (8-69)







Extreme Deuteranomalous

= Deuteranopic

Severe Deuteranomalous

Moderate Deuteranomalous

19
18
10:
tt
tt
He
113
ts Mild Deuteranomalous
eo 116
mH ike
mm 118
— ig
ee 120
— (24-122
— 123
me 124- 125
re 126
reo 127 -
— 128 2 Borderline Defective -
L 1 n A 1 L 4 wi Deuteranomalous
0 10 20 30 40 50 60 70

Ficure 2. Range of anomaloscope matches made by deuteranomalous and deuteranopic subjects under conditions
of “neutral” adaptation (solid lines) and, where different, chromatic adaptation (broken lines).


to review it and make any changes to correct the
order. The failure criterion was at least two
crossovers in approximately the same direction
on the score sheet: circle.

4. The Farnsworth 100-hue Test (the Farns-
worth-Munsell 100-hue Test for the Examination
of Color Discrimination, Munsell Color Company,
Incorporated, 1957) was designed to measure
color discrimination in the color normal and the
zones of color confusion in the color defective.’
‘The test consists of four hinged boxes, each con-
taining two fixed color reference caps at either
end of one part of the box and one-fourth of the
85 color test caps randomly arranged in the other
part. The subjects were instructed to place the
color caps in order so that each cap was placed
between the two caps most like it in color. Sub-
jects were told to work in any order from either
reference cap. The scoring procedure was iden-
tical to that described by the test author.© An
error score of 100 or more was considered failing.

All of the above tests were administered in a
darkened room with test illuminaton supplied by
a Macbeth easel lamp with daylight filter to ap-
proximate C.I.E. Source C.

5. The Color Threshold Tester (SAM CTT)
(Macbeth Corporation), which was developed
for an Air Force criterion,’ consists of a test
light in front of which are two discs, each con-
taining eight filters. The upper dise contains
neutral density filters for varying the luminance
of the test light, while the lower disc contains
color filters for varying the test color. The sub-
ject was seated ten feet from the instrument in a
dark room. All eight colors, at the highest Iumi-
nance, were shown to the subject and named for
him by the examiner before testing. The subject
was instructed to report the color of each test
light, and to use only the color names shown to
him before testing. The subject was told to guess
when not sure. All colors were shown at the
lowest luminance first in the order prescribed by
the test author. The order was reversed at each
successively higher luminance. The criterion for
failure was a score of 49 or less.

6. The Farnsworth Lantern (Farnsworth Lan-
tern for Testing Color Vision, Macbeth Corpora-
tion) was designed for the screening of Navy
personnel.s The Lantern permits successive pre-
sentation of nine vertically arrayed pairs of lights
representing all possible combinations of the two

positions and of the three colors, red, green, and
white. Subjects were seated eight feet from the
Lantern in a lighted room. Each subject was
instructed to identify the colors of the pairs of
lights presented to him. All nine pairs of lights
were presented in random order and if the sub-
ject made no errors in identifying the pairs in
the series, he was passed. If there were any
errors, two additional series were run. Failure
criterion was an average of more than one error
per series of nine color pairs for the last two
series.

7. The Titmus Plate (Color Perception Plate
of the Titmus Vision Tester, Aeromedical model,
Titmus Optical Company) was added to the test
battery when Group 2 subjects were run. The
test was designed to detect color deficiency, but
not to diagnose the type of defect. It consists of
a transilluminated plate containing six repro-
duced Ishihara Pseudo-Isochromatic Plates. The
plate is viewed binocularly through a stereoscope
that presents an image of the plate at an optical
distance of 20 feet. The test was administered
in an illuminated room. The subject was in-
structed to identify the numbers in each circle
on the plate. Failure criterion was any error.

8. Each subject was given an anomaloscope
examination with a Nagel-type anomaloscope
(Schmidt and Haensch). The instrument pre-
sents a monocular view of a 2°10’ circular bipar-
tite field, The subject is required to match the
two halves of the field to produce the Rayleigh
equation, a variable mixture of wavelengths of
670 nm and 546 nm in one half and 589.3 nm of
variable luminance in the other. The examina-
tion procedure began by asking the subject to
fixate the Trendelenburg adaptation light for
two minutes after which the subject was asked
to match the halves of the bipartite field using
both control knobs. For succeeding matches, the
examiner set the red-green mixture, while the
subject attempted to make a match by varying
the luminance of the yellow field. This proce-
dure was continued until the examiner reached
the limits of the subject’s range. Between
matches the subject was asked to regard the
adaptation field for thirty seconds. After the
subject’s range was determined under conditions
of “neutral” adaptation, the range was redeter-
mined for conditions of chromatic adaptation
by asking the subject to look through the eye-


COLOR DEFECTIVE VISION AND THE RECOGNITION OF AVIATION
COLOR SIGNAL LIGHT FLASHES

I. Problem.

Candidates for Federal Aviation Administra-
tion medical certificates (Classes IT and III)
must be able to discriminate among aviation sig-
nal red, white, and green. To test for this re-
quirement, a variety of commercial color vision
tests have been approved for use by FAA-desig-
nated Aviaition Medical Examiners, although
many of these tests have not been standardized
against specific aviation requirements, Many in-
vestigators® have compared these tests for clinical
efliicacy in classifying and quantifying color de-
fective vision. The purpose of the current study
was to compare several of these tests, together
with some currently non-FAA-approved clinical
tests for predictive value when used with an
aviation criterion.

II. Method.

A. Subjects, Five thousand and sixteen vis-
itors to the 1968 Oklahoma State Fair were
screened using the American Optical H-R-R, the
Dvorine plates and the Farnsworth Panel D-15
(these tests are described below) with 460 of
these fair-goers showing some degree of color de-
ficiency. These 460 people were invited to par-
ticipate in this investigation. From this group,
49 men and five women were tested on the test
battery. Additional subjects were obtained from
Tinker Air Force Base. Arrangements were
made to screen 4000 active duty medical records
for evidence of color defect. Two hundred forty-
seven Air Force personnel were so identified and,
of these, 73 men completed the Group 1 test bat-
tery. These 127 subjects comprise the Group 1
test. population.

One year later, the Air Force medical records
were again screened and 369 additional defectives
were identified. At this time, the Titmus Vision
Tester Color Plate was added to the test battery
and 71 men completed the battery and comprise
the Group 2 test population.

B. Tests and Procedure. The complete test
battery is described below. Because the Titmus
Vision Tester was not used at the time they were
run, Group 1 subjects did not receive that test.

1. The A. O. H-R-R plates (American Optical
H-R-R Pseudoisochromatic plates, 2nd edition,
American Optical Company, 1957), which are
really pseudoachromatic plates, were designed? *
to discriminate color defective vision from nor-
mal color vision, to classify type of defect, and
to indicate the degree of defectiveness. The test-
ing procedure prescribed by the test authors was
followed except that no repetition was given.
Each- subject was shown the four demonstration
plates and asked to identify any symbols he saw.
He was told there would be one, two, or no
figures on each plate. He was then shown the
test plates and asked to identify the figures. The
first response was recorded and no corrections
were allowed. For this study, a subject was
scored as failing if any errors were made in
plates 12-14 of the diagnostic series.

2. Of the Dvyorine plates (Dvorine Pseudo-
Tsochromatic Plates, 2nd edition, Harcourt,
Brace and World, Incorporated, 1953), the 15
numerical plates, including one demonstration
plate, were used. The seven plates for illiterates
and the nomenclature test were excluded from
the study. Each subject was shown the plates
and asked to identify the numbers. ‘The criterion
for failure was 12 or more errors on plates 1-15.

3. The Farnsworth Panel D-15 (Farnsworth
Dichotomous Test for Color Blindness, Panel
D-15, Psychological Corporation) was designed
to distinguish the severely color defective from
the color normal and the moderately color defec-
tive.® The test consists of 15 plastic color caps
plus a rack containing a reference color cap
mounted at one end. Each subject was instructed
to place the color caps in order, so that each cap
was placed next to the caps most like it in color.
After completing the test the subject was asked



ACKNOWLEDGMENTS

The authors express their appreciation to Col. William F. LaFon for
his assistance in acquiring and testing military personnel at Tinker Air Force
Base, Oklahoma City, and also thank Maj. Gerald P. Ellsworth, Lt. Donald
Ashkenase, and Lt. Victor G. Hill for their generous assistance during the
testing procedures. The testing booth at the 1968 Oklahoma State Fair was
set up with the generous help of Dr. Harry L. Gibbons.