暗黒中での見えの距離の問題

刺激の大きさと見えの距離の関係について

抄録

The relation of the apparent distance of an object to its visual angle was explored in situations somewhat similar to that reported by Ittelson (8, 9).
Two objects were presented in darkness. The standard stimulus was a luminous square which moved back and forth between two points 150 and 300cm. from the observer. When the tracks, the size controlling device, were set parallel, the size of the square would be constant in spite of its motion (stimulus X). Then the near end of the tracks was narrowed and the far end widened, the size of the square would decrease rapidly as it approached the O (stimulus Y). Stimulus Y at all times subtended the same angle as stimulus X did. In addition, the size of the square could be varied continuously in the static presentation. The standard stimulus was viewed monocularly.
The comparison stimulus, the King of Japanese chess-man (2.3×2.8cm.) was viewed binocularly 30° left to the standard. The O could shift it back and forth smoothly by turning a wheel.
Exp. I. Radial motion situation. Stimulus X and Y were used, whose size at their extreme distance were shown in Table 1. They travelled between both extremes two times and then were turned off. The O was allowed to shift the comparison stimulus and set it at equi-distance to the apparently farthest (or nearest) point of the standard. Four trials for each point were made (Table 2). On stimulus Y, apparent direc tion of movement was in the opposite direction of physical movement. The dif ferences of apparent distance between stimulus X and Y were insignificant for both of the farthest and the nearest point. The distance-ratio of the farthest point to the nearest was 1.90 in stimulus X and was 1.75 in stimulus Y.
Exp. II. Static presentation. The procedure was identical with Exp. I except the static presentation of the standard stimulus (Table 3). The results were shown in Table 4. The differences between A and D, and those between B and C were insignificant. The distance-ratio of B, C to A, D was 1.48.
The apparent distance of stimuli, for both situations, was determined by their visual angle subtended, and the reduction of distance-ratio in Exp. II showed the effect of motion of the stimuli.
Exp. III. The standard stimuli (Table 3) were presented in randomized order. The starting point of the comparison stimulus was at 73cm, from the O. Eight trials for each stimulus were made (Table 5). Remarkable individual differences were found, which could be classified in two types. One was characterized by the differences of distance-ratios (see Fig. 1 and Fig. 2). It would correspond with the “set” in comparison process. The other was characterized by the differences of apparent distance rather than that of ratios. The apparent distance for group II (Fig. 6) was significantly farther than group I (Fig. 5). All of the Os, who previously experienced such experiment, fell in group II. More than half of the unexperienced Os were included in group I. These differences might correspond with the effect of experience.