A coloured figure on a different coloured ground begins to lose sharpness and simplifies its form, when its brightness approaches that of the ground on which it lies. In other words, this means that a mere colour difference without an accompanying difference in brightness has a very low organizing power . This phenomenon has been already discovered and investigated by S. Liebmann (Psychol. Forsch., 9, 1927.), and further K. Koffka and M. R. Harrower, who called this phenomenon “Liebmann effect”, have inquired into it.by taking into account the interdependence of “colour and organization” (Psychol . Forsch., 15, 1931,). They have proved that the colour in any part of the field depends upon the formal characteristics of this figure. From such a standpoint, we attempted to confirm the influence of form upon the Liebmann effect.
1. (Experiment 1) What will happen to a figure (in our experiment, a green figure)on a ground (blue), if the difference between the bnightness of the figure and the ground changes gradually,( in our experimental procedure,t here was no difference in their brightnesses at first and then the brightness of the figure was gradually increased by rheostat without changing that of the ground)? Under such a condition, we observed the changing appearances of many various figutes which had been used by M. Wertheimer in order to demonstnate the factors of “Prägnanzgesetz”. We could divide these appearances into five stages.
a) At first, it seemed that we saw green clouds in blue sky . There was almost no form.
b) Those green clouds began to segregate themselves but we could not say what it was.
c) In the third stage, the segregated form could be slightly observed . The parts of the whole figure, however, appeared, as it were floating and being unstable at every moment, separately and disorderly on the blue ground.
d) In the fourth stage, all the parts of the figure were organized in accordance with “Pägnanzgesetz” for example, two lines, which were relatively nearer, were phenomenally grouped into one rectangle. And in this stage, the better the form of a part, the more stable and saturated was it.
e) In the last stage, all the parts of the whole figure were distinctly localized on the ground and were organized in one definite order. Now, its colour showing a good saturation, had “Eindringlichkeit” and appeared as if it spreaded out of the contour of its figure.
2. (Experiment 2-6) In these experiments, we proved quantitatively by measuring the critical zone of Liebmann effect that the better the form of figure, the more difficult it was to enter into the state of Liebmann effect. Otherwise expressed, the rank order of the width in the critical zone of each figure which had the equal area, was as follows: circle, square, triangle and the irregular form gure (see Fig. 10 in the Japanese text). The same was true of the three dimfeinsional figures.
The explanation for such a behaviour of various figures concerning the Liebmann effect as we have described above, is not difficult to give. We shall be able to understand its behaviour by considering “the simplicity of form” and moreover “the interdependence of organization and saturation”
3. (Experiment 7-9) In Fig. 24 a, b and c in the Japanese text, the V-part (we called it c-pt.) was led into the state of Liebmann effect by changing its brightness, while the other part (u-pt.) of the same figure remained in clear articulation. Under these conditions, the Liebmann effect was more difficult to take place in the V-part of Fig. a than those of Fig.
