Enigma

from Michael’s   Visual Phenomena & Optical Illusions

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Stare at the centre of the figure for a while. Some ‘scintillating’ activity will build up in the violet and blueish annuli. Some observers also report a circular rotation within these regions; things will begin to “run around in circles”.

This image is called “The Enigma” (≈1984) by the Isralian painter Isia Léviant (1914–2016). It was being presented in a permanent exhibition “Euréka”, Palais de la Découverte, Paris. [I have not been able to dig up more information, since the people who had worked on this project are no longer at the Palais de la Découverte.] New information: The painting is now at the National Gallery of Art, Washington DC, USA.

The image above is not the “real” Enigma, but a very close programmed approximation. The program allows you to change some obvious parameters. Specifically, the ring colours can be changed from the original values to some primary colours; for me this demonstrates that the Enigma effect does not hinge on the specific colour choices.

Comment

The mechanisms for the illusory motion effects are currently unknown (as far as I know, but see Zanker 2004, PDF below), an ‘enigma’. Associated activity in the “motion area” MT (Zeki, 1993) is an interesting –if unsurprising– finding, but does not ‘explain’ the effect. I’m sure eye movements play a role, as often in Op Art employing regular patterns. But it’s unexplained why the apparent motion should also occur within the homogenous rings.

About Isia Léviant I found this: “Isia Léviant was an Israeli Postwar & Contemporary artist who was born in 1914” here. Here is a little more. When reading his 1982 and 1996 articles it becomes clear that he was very aware of contemporary pertinent science (for instance, he had contact with Donald M. MacKay and Torsten Wiesel) and quite systematically varied parameters to achieve the most striking mixture of effects.

There is some confusion between sources of dating the painting. Léviant himself gives May 1981 as “designing a spinning picture” in his 1982 paper and goes on “The new Museum of Science and Industry (to be opened in 1984–85), now being built in Paris at La Villette, has commissioned me to make a 138 x 138 cm spinning picture”. So there seem to exist various versions, the design above is probably from ≈1984.

Sources

Léviant I (1982) Illusory motion within still pictures: The L-effect. Leonardo 15:222–223

Zeki S, Watson JD, Frackowiak RS (1993) Going beyond the information given: the relation of illusory visual motion to brain activity. Proc R Soc Lond B Biol Sci 252:215–22

Léviant I (1996) Does ‘brain-power’ make Enigma spin? Proc R Soc London B 263:997–1001

Barch D, Kumar T & Glaser DA (2003) Modeling the illusory motion of Enigma with an excitable neuronal array [Abstract]. Journal of Vision, 3:72a

Zanker J (2004) Naturwissenschaften 91:149–156 [PDF]