TABLE 1,--Validity coefficients for the AOC, Dvorine, and equation-derived pseudoisochromatic

plate tests (using total, accepted pass/fail, and optimal pass/fail scores for each) with

the pass/fail score on the signal light gun (SIGLIGUN) test as the criterion, The values

in parentheses are the estimated cross-validation coefficients..

Daytime SIGLIGUN Administration Nighttime SIGLIGUN Administration

Total Test Accepted Optimal Total Test Accepted Optimal
Plate Score for Pass/Fail Pass/Fail Score for Pass/Fail Pass/Fail
Test Pilates Score - Score Plates Score Score
AOC (1965) 0.78 0.77 0.78 0.50 0.44 0.46
Dvorine 0.79 0.75 0.77 0.48 0.47 0.47
Equation-derived
by unit weight 0.81 none 0.81 0.51 — 0,52
multiple regression (0.81) (0.51)

Note: Although not best suited for these data,
using a least-squares multiple regression model prov:

validity coefficients for an equation-derived test
ide a comparison that might interest some investigators,

The computations yielded validity coefficients of 0,84 and 0.64 and cross-validation coefficients of 0,82
and 0.59 for daytime and nighttime criteria, respectively,

The same procedure was followed using the
nighttime SIGLIGUN test scores as the cri-
terion. The best set of predictors consisted of
eight AOC plates (plate numbers 1, 2, 5, 6, 7, 9,
11, and 12) and seven Dvorine plates (plate
numbers 5, 6, 7, 10, 11, 12, and 13). The corre-
lation (phi) coefficients for each test are given
in Table 1. There were no significant differ-
ences between any of the correlations, an indi-
cation that all three plate tests are equally good
as predictors of nighttime performance on the
SIGLIGUN test.

When the validity coefficients for the daytime
and the nighttime administrations of the SIGLI-
GUN test were compared, the differences (e.g.,
0.78 versus 0.50, the respective correlations of
the AOC total test score with the daytime and
nighttime administrations of the SIGLIGUN
test) were significant for all plate tests. This
finding agrees with previous research?! and
indicates that, although the pseudoisochromatic
plate tests may be good predictors of daytime
SIGLIGUN test performance, they may not be
adequate predictors of nighttime performance.
However, in making this type of comparison, it
should be noted that the ratio of ‘color normals
to color defectives determines one set of the
marginal totals and can thereby greatly affect
the obtained phi coefficients. Therefore, caution
is advised in making comparisons of phi co-

efficients (or product-moment coefficients on
dichotomized data) when the ratios of color
normals to color defectives differ for the groups
being compared (for example, the difference in
this study between the percentages of subjects
failing the nighttime SIGLIGUN test and those
failing the daytime test).

B. Efficiency of Tests and Evaluation of Cut
Scores. Previous evaluations of color vision
tests as predictors of SIGLIGUN test perform-
ance*®»® have used pass/fail categories based
on only one cut score (the “recommended” one)
for each test. However, it might be useful to
evaluate the predictive validity of a clinical test
independently of the cut score, as in signal de-
tection theory (TSD) where such an evaluation
of the sensitivity of a measure is a standard
procedure.* To evaluate predictive validities of
the tests in this study, we used the probability
of a false alarm and the probability of a miss
(ie. the probabilities of making the two types
of incorrect decisions). Other studies have
evaluated color vision tests in terms of the per-
centage of misses and false alarms, where a miss
occurred when a subject passed the clinical
(predictor) test and failed the SIGLIGUN
(criterion) test® and a false alarm occurred when
the subject failed the predictor test and passed
the criterion test.1° In the present study, a miss
rate and a false alarm rate are described in the



‘As the tests are presently used by the FAA,
scores of 5 or more errors on the AOC and 12 or
more errors on the Dvorine are classified as fail-
ing. Our data indicate that the cut score pres-
ently used for the AOC test may be somewhat
too strict while the cut score for the Dvorine
test appears to be too lenient (p(miss) =0.18) ;
a lower cut score for the Dvorine test (e.g., nine
or more errors classified as failing, thus lowering
p(miss) to about 0.07) could be adopted; how-
ever, since a change on the AOC test would
involve allowing only one additional error, no
modification of this test appears warranted.

D. Farnsworth Lantern Test. Figure 3 pre-
sents the false alarm and miss rates with the
Farnsworth Lantern test given in both a dark-
ened room and a lighted room as the predictor.
For both conditions of administration of the
Lantern test, with the daytime administration
of the SIGLIGUN as the criterion, the miss
rates are low, and for a given miss rate, the false
alarm rate is low, which are indications that this
test is a good predictor of performance on the
daytime SIGLIGUN test. These data also in-
dicate that the presently used cut score (an aver-
age of more than one error per trial is failing)
is appropriate when the Farnsworth Lantern
test is given in a lighted room (at this cut score,
the p(miss) <0.06 and the p(false alarm) <0.08).
The miss rate was slightly higher (p(miss) <0.12)
when the Farnsworth Lantern test administered
jn a darkened room was the predictor test. Since
the present instructions recommend administra-
tion in a lighted room and since the present data
do not indicate any advantage to testing in the
dark, no change in the administration procedure
for the Farnsworth Lantern appears useful.

When SIGLIGUN test scores from the night-
time administration of the test were used as the
criterion, the Farnsworth Lantern test given in
a darkened room and a lighted room yielded
similar results (Figure 3). For any Lantern
test cut score suggested in the literature (i.e., up
to three errors’), both test conditions yielded
very low miss rates. The false alarm rates were
slightly higher for nighttime than for daytime
administration, an indication that the Lantern
test, like the pseudoisochromatic plates, is a
stricter predictor of performance on the night-
time SIGLIGUN test than on the daytime test
(ie., there is an increase in the false alarm rate
and a decrease in the miss rate).

E. Anomaloscope. In Figure 4, the miss rates
and false alarm rates are presented with the
absolute value of the matching range on the
anomaloscope as the predictor to allow a com-
parison of two methods for obtaining a matching
range score on the anomaloscope; Le. neutral
and chromatic adaptation. The data suggest
that the use of the matching range value ob-
tained under chromatic adaptation is a more
appropriate predictor, since it yielded false alarm
and miss rates that were lower than those ob-
tained with the matching range under neutral
adaptation. We suggest that, as a predictor of
performance on the daytime SIGLIGUN test,
a range of less than 30 scale units is preferable
(p (miss) <0,05) and a range between 31 and 40
scale units is acceptable (0.05<p(miss) <0.15).
As a predictor of performance on the nighttime
test, a range of 43 scale units or less appears
preferable (p(miss) <0.05) and a range between
44 and 48 units is acceptable (0.05<p(miss) <
0.15).

F. Color Threshold Tester. In Figure 5, miss
and false alarm rates are presented for the CTT
as the predictor. Unlike the results of other
tests in this study, CTT test scores reflect the
number of correct responses rather than the
number of errors. When daytime SIGLIGUN
test performance is used as the criterion, for the
cut score presently used (ie. a score of 50 or
better is passing) and for adjacent cut scores,
the false alarm rates are comparable with the
other tests but the miss rates are slightly higher.
If a stricter cut score were to be selected (eg.,
one so. that the p(miss)=0.05), then the false
alarm rate would be higher than for the other
tests (e.g., p=0.20 as compared with p=0.10 for
the pseudoisochromatic plate tests). With night-
time SIGLIGUN test performance as the cri-
terion and with the presently used cut score (or
adjacent cut scores) for the predictor test, the
p(miss) =0 and the p(false alarm) =0.20 (these
data values are not given in Figure 5). There-
fore, as a strict test for predicting performance
on the nighttime SIGLIGUN test, the CTT with
its presently used cut score is satisfactory be-
cause its false alarm rate is lower than that of
the other tests at this miss rate.

G. 100-Hue Test. The 100-Hue test, a very
sensitive clinical device that is not-currently used
by the FAA in testing pilot applicants, might


we recorded the pass/fail score on each plate and
the total number of errors on each test. For the
Farnsworth Lantern test (given in a lighted
room and a darkened room) and the 100-Hue
test, the total number of errors was recorded.
For the Panel D-15 test, the number of cross-
overs was tabulated; for the anomaloscope, the
absolute value of the range and midpoint of
matches for neutral and chromatic adaptation
were recorded; and for the CTT, the number of
correct responses was recorded. Separate pass/
fail scores were recorded for the daytime and
the nighttime administrations of the SIGLIGUN
test.

III. Results and Discussion.

‘As an estimate of test-retest reliability for the
AOC and the Dvorine tests, we calculated co-
efficient alpha or KR-20° from the data obtained
by Steen e¢ al. (coefficient alpha is a measure of
internal consistency of the test). Our reliability
estimate of 0.94 for the AOC test is in close
agreement with Seefelt’s* test-retest reliability
coefficients of 0.94 when the test was given in a
mass-testing situation (i.e, on a limited-time,
assembly line basis) and of 0.98 when it was
given in a clinical setting (N=183 color defec-
tives and 226 color normals). Our reliability
estimate for the Dvorine test was 0.98; we know
of no other test-retest reliability data for this
instrument.

Since the test-retest measures we obtained with
the SIGLIGUN were for tests given in both
daytime and nighttime hours (i.e., nonparallel
measurements), we used Guttman’s* Lambda
four and obtained a reliability estimate of 0.64.
Note that this is a lower bound estimate of the
reliability; if the retest measurements for the
nighttime SIGLIGUN condition had been ob-
tained at night and those for the daytime condi-
tion had been obtained in the daytime, the
test-retest reliability coefficients for both condi-
tions of test administration would probably have
been much higher than this reliability estimate.
There appear to be no other published test-
retest reliability data for the SIGLIGUN.

A. An Equation-Derived Set of Pseudoiso-
chromatic Plates. The correlations of the indi-
vidual plates from the AOC and the Dvorine
tests with the pass/fail scores for the daytime
and nighttime administrations of the SIGLI-

GUN test ranged from 0.26 to 0.79. Using the
28 plates from these two tests (demonstration
plates were omitted) as the predictors anu the
pass/fail scores on the daytime and the night-
time SIGLIGUN tests as the criteria, we calcu-
lated two multiple regression equations in a
stepwise manner to select a series of plates that
would act as the best predictor of SIGLIGUN
performance.

For daytime scores on the SIGLIGUN test,
the best set of predictors consisted of eight AOC
plates (plate numbers 1, 2, 3, 4, 6, 8, 12, and 13)
and six Dvorine plates (plate numbers 2, 5, 6,
10, 11, and 14). The rationale for including
only 14 plates was that the squared semipartial
correlation had approximately reached asymp-
tote when the 14th plate was added. Since pre-
diction using a least-squares multiple regression
equation is not generally recommended when
prediction is based on individual test items.rather
than tests in a battery, a unit-weight multiple
regression equation with the 14 selected plates
was used.

Using the procedure explained in the next
section, we chose optimal cut scores for each of
the three plate tests (ie, the AOC, Dvorine,
and equation-derived tests). The cut scores se-
lected for failure were seven or more errors on
the AOC test, seven or more errors on the
Dvorine test, and six or more errors on the
14-plate equation-derived test. The correlations
for the total test score, currently accepted pass/
fail score, and selected optimal pass/fail score
for each of these tests with the pass/fail score
on the SIGLIGUN test were calculated. These
validity (phi) coefficients for the daytime ad-
ministrations of the SIGLIGUN test are pre-
sented in Table 1. There were no significant
differences (F<1.0) between tests or between
types of scores on the tests (e.g., the difference
between the correlation of 0.78 for the AOC
total test score versus 0.77 for the accepted pass/
fail score on the AOC test was not significant,
nor was the difference between 0.77 for the cur-
rently accepted pass/fail score on the AOC test
versus 0.75 for the accepted pass/fail score on
the Dvorine test). This indicates that all three
plate tests are equally effective as predictors of
a pass/fail score for the daytime administration
of the SIGLIGUN test.


same way. The four possible TSD events in the
present study are defined in Figure 1, where, for
instance,
p(miss) =p (pass predictor | fail criterion).

The above equation is read as: “The probability
of a miss equals the probability of passing the
predictor test given that the criterion test will be
failed.” Other equations in Figure 1 are read in
a similar manner.

Signat light gun (criterion) test

Pass Fall
Pass Hit Miss
Clinical
(predictor)
test
False Correct
Fail Alarm Rejection

p (Hit) = p(Pass predictor | Pass criterion)
p (Miss) © p(Pass predictor | Falt criterion)

p (False Alarm) = p (Fall predictor | Pass criterion)
p (Correct Rejection) = p (Fall predictor | Fall criterion)

Freuge 1, Predictor test-criterion test matrix and defi-
nition of decision theory events.

Fach color vision test used in this study was
evaluated against two criteria: the SIGLIGUN
test given in the daytime and at night. Figures
2 through 7 show the probability of a miss
(p(miss)) plotted against the probability of a
false alarm (p(false alarm)). The cut score for
a given miss rate and false alarm rate combina-
tion can be determined by referring to the scale
for each test at the top of the appropriate figure.
(Miss and false alarm rates were plotted after a
p-to-z transformation’; no misses occurred for
cut scores below the lowest value on the error
scales in the figures.) For all tests, as the cut
score is made more stringent, the miss rate de-
creases and the false alarm rate increases, and
as the cut score is made more lenient, the miss
rate increases and the false alarm rate decreases.
In many practical testing situations (g., avia-

tion), a miss is considered more serious than &
false alarm. For example, if a miss occurs in
aviation, a pilot may be allowed to fly under
circumstances for which he may not be qualified ;
however, if a false alarm occurs, a pilot can
request a “second chance” (ie. a chance to dem-
onstrate his ability to discriminate color in a
practical situation). Therefore, in the compari-
son of tests, an “acceptable” miss rate (or the
probability of a miss) should be selected and
then the false alarm rates for the tests at that
miss rate should be compared. The test with
the lower false alarm rate for a given miss rate
is the better predictor of performance oni the
SIGLIGUN test. (We recommend a miss rate
of approximately 0.01 to » maximum of 0.15.)
Since a miss rate of 0.50 (ie. 50 percent) or
greater in a practical testing situation is unsatis-
factory, data for miss rates greater than 0.50 are
not given.

C. Pseudoisochromatic Plate Tests. Figure 2
shows the miss and false alarm rates for the
pseudoisochromatic plate tests with each of the
two SIGLIGUN test administrations as the cri-
terion. On the nighttime administration, all
three plate tests were approximately equal in
efficiency (ie, for a given miss rate, the false
alarm rates were approximately equal). On the
daytime administration, the AOC and Dvorine
tests were again approximately equal in ef-
ficiency; however, for miss rates below p=0.15,
the false alarm rates for the equation-derived
plate test were somewhat lower than the false
alarm rates for the AOC and Dvorine tests.
This suggests that the equation-derived test may
be slightly preferable to the AOC or Dvorine
test as a predictor of performance on the day-
time SIGLIGUN test. A more definitive state-
ment would require a cross-validation study with
a different subject sample.

In a comparison of the day and night admin-
jstrations of the SIGLIGUN test, two factors
should be noted concerning the nighttime con-
dition: (a) for a given miss rate the false alarm
rate was much higher, and (b) for a given cut
score there was a general trend for the p(miss)
to be lower and the p(false alarm) to be higher.
These findings are in agreement with the results
of previous research on the AOC and Dvorine
tests® #° and indicate that, for a selected cut score,


80r
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Ficure 7. Miss and false alarm rates for the D-15 test as a predictor of performance on the daytime (D) anu
nighttime (N) administrations of the SIGLIGUN test.

4, As a predictor of daytime SIGLIGUN test
performance, the Farnsworth Lantern test ad-
ministered in a darkened room (the instructions
specify a lighted room) affords no advantage
(and perhaps some loss of predictive efficiency).

5. The 100-Hue and Panel D-15 tests (not
currently used by the FAA) are not good pre-
dictors of performance on the SIGLIGUN test.

6. When the absolute value of the matching
range on the anomaloscope is used as a predictor
of performance on the SIGLIGUN test, the

matching range obtained under chromatic adap-
tation has greater predictive efficiency than the
range obtained under regular adaptation.

7. All the tests cited above were stricter pre-
dictors of SIGLIGUN test performance at night
than during the day.

The findings and suggestions made in the pres-
ent study apply only to the situation in which
an attempt is being made to predict performance
on tests’ using the SIGLIGUN (or a similar
device).

REFERENCES

p

Browne, M. W.: Precision of Prediction. (Interoffice

memorandum) Research Bulletin RB-69-69, Prince-

ton, New Jersey, Educational Testing Service, 1969.

2. Federal Aviation Administration: Guide for Avia-
tion Medical Examiners, Washington, D.C. FAA
Office of Aviation Medicine, 1970.

3. Guttman, L.: A Basis for Analyzing Test Retest.
Reliability, PSYCHOMETRIKA, 10 :255-282, 1945,
4. Green, D. M., and J. A. Swets: Signal Detection
Theory and Psychophysics, New York, John Wiley

and Sons, Inc., 1966.

5. Lewis, M. F., and J. A. Steen: Colour Defective
Vision and Recognition of Aviation Colour Signal
Light Flashes. In The Perception and Application
of Flashing Lights: Proceedings of an International
Symposium Held at Imperial College, London, in
April 1971, London, Adam Hilger Ltd., 1971.

6. Lord, F. M., and M. R, Novick. Statistical Theories

of Mental Test Scores, Reading, Massachusetts,

Addison-Wesley Publishing Company, 1968.

7. Schmidt, I.: Comparative Evaluation of the New
London Navy Lantern for Testing Color Perception.
Project Number 21-29-00, Randolph Field, Texas,
USAF School of Aviation Medicine, 1951.

8 Seefelt, E. R.: An Evaluation of the Validity and
Reliability of the AOC 15-Plate Pseudo-Isochromatic
Test in Routine Testing, AMERICAN JOURNAL
OF OPTOMETRY AND ARCHIVES OF THE
AMERICAN ACADEMY OF OPTOMETRY, 41:371-
381, 1964.

9. Steen, J. A., W. E. Collins, and M. F. Lewis: Utility
of Several Clinical Tests of Color Defective Vision
in Predicting Daytime and Nighttime Performance
With the Aviation Signal Gun, AEROSPACE
MEDICINE, 45 :467-472, 1974.

10. Steen, J. A, and M. F. Lewis: Color Defective
Vision and Day and Night Recognition of Aviation
Color Signal Light Flashes, AEROSPACE MEDI-
CINE, 48:34-36, 1972.



Technical Report Documentation Page

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FAA-AM- 75-1

4. Title and Subtitie 5. Report Date
PREDICTIVE VALIDITIES OF SEVERAL CLINICAL j—panuary 1975 =i
COLOR VISION TESTS FOR AVIATION SIGNAL "Performing Organization Code

LIGHT GUN PERFORMANCE

8. Performing Organization Report No.

7 Avbor's) Karen N. Jones, M.S., Jo Ann Steen, B.A.,
and William E, Collins, Ph. D.

9. Performing Organization Name and Address. 10. Work Unit No. (TRAIS)
FAA Civil Aeromedical Institute
P.O, Box 25082 TI. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name ond Address

Office of Aviation Medicine OAM Report
Federal Aviation Administration
800 Independence Avenue, SW, 14. Sponsoring Agency Code

Washington, D.C. 20591

15. Supplementary Notes

This research was conducted under Tasks AM-A-73-PSY-45 and AM-D-74-PSY-45,

16. Abstract

Scores on the American Optical Company (AOC) test (1965 edition), Dvorine test,
Farnsworth Lantern test, Color Threshold Tester, Farnsworth-Munsell 100-Hue test,
Farnsworth Panel D-15 test, and Schmidt-Haensch Anomaloscope were obtained from 137
men with color-defective vision and 128 men with normal color vision, The validity
of each of these tests in predicting scores on the aviation signal light gun was
assessed by using daytime and nighttime administrations of the light gun as the
criteria. Two "best sets" of plates from the AOC and Dvorine tests were selected
by calculating a multiple regression equation in a stepwise manner with the night-
time and then the daytime administration of the signal light gun test as the
criteria, Based on a graphic presentation of the miss and false alarm rates for
each test at various possible cut scores, suggestions were made regarding the use
of each test and the selection of optimal pass/fail scores,

17. Key Words 18. Distribution Stotement
Aviation Signal Light Gun [Document is available to the public through
Color Defect the National Technical Information Service,
Color Vision Tests Springfield, Virginia 22151,
Test Standards
19. Security Classif. (of this report) 2. Security Classif. (of this page) Bi No. of Pages | 22, Price
$3.00 PC
Unclassified Unclassified 9 $ .95 MF

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized



each test was a stricter predictor of performance
on the nighttime as compared to the daytime
SIGLIGUN test. This finding is not unexpected,

80

7 e ° 10

since previous research” has indicated that it is
easier to pass the SIGLIGUN test at night than
in the daytime.

80 -

8 9 10 " 2
AOC test AOC test
40F 7a 9 ON 2 3 AO 910," 12 134
Dvorine test Dvorine test
ed 7 8 9 0 " 2 Or 910,11 2 “3 7
‘Unit weight mult. regression Unit weight mutt. regression
= 20
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1 1 1 a n L 1 a
05 410 +20 30.40.80 0S 10 20 3040.80
p (Miss) p (Miss)

Figure 2. Miss and false alarm rates for the pseudoisochromatie plate tests as predictors of performance on the
daytime (D) and nighttime (N) administrations of the SIGLIGUN test,

& 4
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08 10

p (Miss)

+20 30 40.80

Lantern as a predictor of performance on the daytime

(D) and nighttime (N) administrations of the SIGLIGUN test.

5





PREDICTIVE VALIDITIES OF SEVERAL CLINICAL COLOR VISION
TESTS FOR AVIATION SIGNAL LIGHT GUN PERFORMANCE*

I. Introduction.

To obtain an airman medical certificate
(Classes II and III) issued by the Federal
Aviation Administration (FAA), an airman
must demonstrate the ability to discriminate
aviation signal red, green, and white by- passing
an approved clinical color vision test.2 If he
fails the clinical color vision test, he can request
a practical examination using the aviation signal
light gun (SIGLIGUN).° Unless he takes and
passes the practical test, he is issued a medical
certificate with the limitation: “Not valid for
night flight or by color signal control.” Since
an airman can appeal to take the practical test
after failing the clinical test and since the instru-
ment used for administering the practical test
is the same as that used for directing air and
ground traffic at airports, it would appear desir-
able to use clinical color vision tests that have
high predictive validity for performance on the
SIGLIGUN test.

A color vision test approved by the FAA
should be reliable; ie, it should give consistent
results across different testing sessions. If a
test has high reliability, the examiner can be
fairly certain that if the test were readministered
the examinee would make the same, or a very
similar, score and would receive the same “color
normal” or “color defective” classification. Al-
though the results of a color vision test can
greatly affect a person’s life, reliability data on
many of the devices are often inadequate (e.g.,
based upon a small sample size) or unavailable.

In a previous study, several clinical color
vision tests were evaluated in terms of predicting
performance on the aviation SIGLIGUN. These

*This paper is based on the first author's thesis,
which completed her M.S. degree requirements in the
Department of Psychology at the University of Okla-
homa. Constructive criticism and guidance from
Charles F. Gettys and W. Alan Nicewander, members
of her thesis committee, are gratefully acknowledged.

tests included four pseudoisochromatic plate
tests (both the 1940 and 1965 editions of the
American Optical Company (AOC) test, the
Dvorine test, and the color plate from the Titmus
Optical Company (T/O) Vision Tester), the
Farnsworth Panel D-15 test, the SAM Color
Threshold Tester (CTT), the Farnsworth 100-
Hue test, the Schmidt-Haensch (Nagel-type)
Anomaloscope, and the Farnsworth Lantern test
(given in both a lighted room and a darkened
room). The purpose of the present study was
to further analyze the data obtained by Steen
et al.® in order to (a) estimate the reliability of
the AOC (1965 edition), Dvorine, and SIGLI-
GUN tests; (b) select a “best set” of plates
from the AOC and Dvorine tests for use in pre-
dicting performance on the SIGLIGUN and
obtain an estimate of the cross-validation co-
efficient’ of this set; (c) compare the efficiency
of seven tests independently of the “approved”
cut score (i.e. the score representing the lowest
number of errors for failure, as recommended
by the FAA or the manufacturer); and (d)
determine if we could select, on any of the tests,
a different: cut score that would act as a better
predictor of a cut score on the SIGLIGUN test.

II. Method.

In a previous study,? 137 men with color-
defective vision and 128 men with normal color
vision were given a battery of clinical color
vision tests and sets of flashes from an FAA
SIGLIGUN in the daytime and at night. We
selected for further analysis seven of the tests:
the 1965 edition of the AOC test, the Dvorine
test, the CTT, the Farnsworth Lantern test, the
Panel D-15 test, the 100-Hue test, and the
Schmidt-Haensch Anomaloscope. Each test was
treated as a predictor of a pass/fail score on the
SIGLIGUN test given in the daytime and the
same test given at night. For both sets of the
pseudoisochromatic plates (AOC and Dvorine),