Double shock for two researchers at the Techno University of Toyohoshi (Japan): they discovered a new optical illusion and shed new light on a century-old paradox at the same time.
Helsen-Judd Effect vs. Kirschmann’s Third Rule
Back in the 19th century: Michel-Eugène Chevrolet, a French chemist, was the director of dyes for royal factories in Goblin. He then became aware of some unexpected incidents related to textile dyes. In his treatise on “the simultaneous opposite law of colors and colored objects”, his son states in the preface that “Mr. Chevrul had received complaints about the quality of some colors emanating from his workshop.“.”It was noted that the lack of vigor due to its dark color was due to the color contrast and came from the color that was applied there“”This observation was the starting point of studies that inspired my father to establish the rules of the ‘law of contrasting colors simultaneously’“”, Continued the chemist’s son. The incident also collided two different theories. Kirschmann’s Third Law and the Helsen-Judd Effect.
“Kirschmann’s third law is one of the five laws of color contrast reported by the German psychologist August Kirschmann in 1891, explain to Science and future Japanese researcher Kova Koida. Color contrast refers to the effect of surrounding colors on the central target, causing the perception of colors to contrast with the environment, called complementary colors.“”The color contrast is more pronounced when the brightness of the circumference and center is equal: this is the fact that krishnavidya excludes“, The researcher continues.
The Helsen-Judd effect is named after the psychologist Harry Helson who saw it in 1938, and the physicist Dean B. who produced it two years later. “When we look at an object, we usually see light reflected by light, Remarried Kova Koida. If the color or brightness of the light changes, the reflected light from the object will also change. However, our visual system can immediately experience the same color as the object. It is an important process that allows a consistent perception of the object at all times“.
But this consistency of colors can sometimes be compromised by “errors”. “An example is the Helsen – Judd effect, an event during which the appearance of color changes according to the brightness of an object (albido, reflection).“, Japanese researchers point out. This effect is determined by the brightness of the environment: if the center of the image is bright, the periphery loses its effect.”But if the center is dark, the contrast from the environment becomes stronger and complementary colors are seen.“, Researcher Concludes. To add more:”Kirschman’s third law states that the contrast is stronger when the brightness between the circumference and center is equal. On the other hand, the Helsen – Judd effect shows that the deeper the center, the stronger the contrast. These theories are clearly contradictory“.
A gray line that turns red
In a study published in the journal November 2020 Scientific report, Kova Koida and his colleague Tama Kanemetsu present a new optical illusion that may well assimilate these two theories. This occurs when a gray line appears red on the border by two white lines on a cyan background.
Therefore this white outline creates optical illusion. If it gets darker, the optical illusion disappears (see video above). But if the gray line becomes darker and the white line persists, the confusion continues. By making the central gray line lighter or darker, researchers were able to play the contrast.
“Results showed that the deeper the gray line, the stronger the contrast effect, which is consistent with the Helsen – Judd effect., Remarried Kova Koida. And on the other hand, when the white outline is removed and the gray line is placed directly on the colored background, the contrast is stronger when the brightness is the same everywhere. This corresponds to Kirschmann’s third law“. Finally, it is the presence or absence of white lines that allows switching between two conflicting theories … and to go from gray to red.