Silencing by Motion
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
Press the ‘stop’ button. Unsurprisingly, the ring refrains from rotating. Now it becomes obvious that all the small disks change their colour; going through 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 by pressing the ‘hue±’ button during rotation; this has nearly no effect during ring rotation.
This effect was published early 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”.
Suchow JW, Alvarez GA (2011) Motion Silences Awareness of Visual Change. Current Biology 21:1–5.
Burr D (2011) Visual Perception: More Than Meets the Eye. Curr Biol 21:R159–R161 (thoughtful editorial)
I am thankful to Jordan for gracefully allowing me to present this demonstration, closely modeled after their publication.