We have studied about some effects on the normal color vision under various environmental conditions, and relationships between the abnormal color vision and road signals.
1) Visual acuity standard and color vision
Three classifications of visual acuity are distinguished in the license of car driving in Japan. These are as follows:
(1) 1st. group ordinary license)
visual acuity-1) above 0.7 with both eyes and above 0.3 with each eye.
2) below 0.3 with one eye, the other eye required to be above O. 7, and visual field more than 150°
2) 2 nd. group (professional license)
visual acuity...above 0.8 with both eyes and above 0.5 with each eye
Here, these steps are named 0.8 for (2), 0.7 for (1)-1 and 0.3 for (1)-2, to the normol vision 1.2 provisionaly.
The visual acuity was measured by the color contrast test types, Landolt's ring, which were combinations of six colors using traffic signs. They were illuminated by fluorescent lamp, mercury lamp and sodium lamp. The relative legibility was compared with normal vision 1.2. On an average the rate was 0.8, 70%, 0.7, 60% and 0.3, 55% of the normal viewing distance. Decreasing rates were always almost constant for different color combinations and different light sources. Between the signs of white and color combinations, white on color sign was better recognized than color on white. Under the mercury lamp, red on blue was hard to see.
On the highway experiment, the legibility of same color combination signs varied depending on the conditions of environs and the pattern of signs.
2) Dazzling
Quantitative static perimetry was used to measure the changes of visual threshold by dazzling. At fi rst, the threshold was obtained at eath 5 degrees point from center to 30 degrees tempolo-horizontal axis, then one dazzling light was put on the side of fixation point. The changing ratio of the threshold with or wothout dazzling, at 5 degrees fom fixation point, was about 1/30 and from 15 degrees to 30 degrees it was about 1/20.
After dazzling to whole retina, the retardation time of perception was obtained for nine color test objects from 401 nm to 658 nm. “The time was not the same for each color, after 3, 000 asb, 5” dazzling. At the fixation point, the maximum retarding was found at 401nm (violet), 502nm (bluegreen) and 603nm (red), At 25 degrees periphery from center, the same result was obtained, but at 502nm, the delay was more marked than that of the center.
3) Abnormal color vision
Among 47 drivers of dyschromatopsy, we found considerable numbers with strong daltonism. The classification by anomoloscope was 12 protan, 5 protanope, 21 deutan, 8 deutetanope and 1 protan or deutan. These dyschromats have not experienced any traffic accident caused by an error of the signal colors.
A color name call test, using a frame by with 145 spots of signal colors on one plate, was done with the dyschromats. The rate of errors was as follows: colorblindness 62.0%, colorweakness 32.2%. It is evident that there is some difference in color perception of dyschromatopsy between the experimental results and discrimination of signals on the traffic.
These results suggest that the red signal of the road traffic should be made larger and brighter than the other colors.

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Attractiveness of colored lights was investigated through cinematograghic records of eye movements and verbal reports of ten observers obtained in the situation of paired presentation of colored lights.
Three indices of attractiveness were used; the initial direction of eye movement, the dominant direction of eye movement, and verbal report.
The main results are as follows:
(1) Three indices of attractiveness were almost consistent with each other.
(2) When the luminance was held constant (64 nt) and high purity colors were used, the order attractiveness of colored lights of five different hues was Red, Blue, Yellow, Green, and White (Illuminant A).
(3) When the excitation purity was kept constant, the attractiveness of red light decreased as its luminance decreased.
(4) When the luminance was kept constant, the attractiveness of red light decreased as the excitation purity decreased.
(5) Five red lights having various luminances and purities were compared with the above mentioned high-purity colors whose luminance was constantly 64 nt. The obtained order of attractiveness was as follows: R (64 nt, 99%), B, Y, R (32 nt, 99%), R (64 nt, 84%), G, W, R (32 nt, 84%), and R (16nt, 99%).

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