Silencing by Motion

from Michael’s   Visual Phenomena & Optical Illusions


What to see

On the right, there is a rotating ring consisting of many coloured discs; best fixate the central cross. Notice anything special? Well, the ring changes rotation direction, we all can easily agree on that.

What to do

Untick the ‘Turn’ box. Unsurprisingly, the ring stops. Now it becomes obvious that all the small disks change their colour; going through the rainbow so to speak.

Starting the ring rotation now and looking closely reveals that the colour change happens all the time, but it is barely noticable during rotation. This can be demonstrated using the ‘Hue’ (change) checkbox during rotation: Whether hue is changing is nearly invisible during ring rotation.


This effect was published in 2011 by Jordan W. Suchow and George A. Alvarez from Harvard University. It subsequently won, deservedly, the “Best Illusion of the Year Contest”.

In the paper by Suchow and Alvaraz and their 2011-VSS poster, not only interesting variants but also several concrete mechanisms are discussed and tested, which I need not go into here. An intuitive explanation: processing global motion presents an overload, which impairs coding of the local details. This is a really new effect, and I think it may be related to “motion blindness”.

A later paper (Turi & Burr 2013) reports that (1) there is a speed threshold (0.2 rps {depending on the absolute spatial arrangement}) and (2) crowding explains the silencing (crowding: “the fact recognition of target in the periphery is difficult when surrounded by other stimuli”). Crowding is well established also for central vision (where small details are more difficult to detect when more details are nearby), but becomes stronger at larger eccentricities.


Suchow JW, Alvarez GA (2011) Motion Silences Awareness of Visual Change. Current Biology 21:1–5.

That provides links to demonstration movies with a number of interesting variants.

You can find them also at their demonstration page.

Burr D (2011) Visual Perception: More Than Meets the Eye. Curr Biol 21:R159–R161 (thoughtful editorial)

Peirce JW (2013) Is it just motion that silences awareness of other visual changes? JOV 13:7, 17

Turi M, Burr D (2013) The “motion silencing” illusion results from global motion and crowding. J Vision 13(5):14, 1–7

I thank Jordan for gracefully allowing me to present this demonstration, closely modeled after their publication.