Moving dots optical illusion reveals the power of silencing

The world is constantly moving and changing all around us, but we're not always able to perceive these changes as they happen. A new optical illusion reveals just how powerful change blindness really is through the mental magic of silencing.

To see the illusion, watch the following short video. Focus on the white speck at the center of the image. As you watch the speck, you'll see in your peripheral vision that the dots are changing color. Then something a bit odd happens...

When the ring of dots started to rotate, the colors seemed to stop changing colors, didn't they? And yet the colors never stopped changing, even when they were rotating. Try playing the video again and, when the ring starts to rotate, shift your focus to a specific dot. The difference should be obvious, but the even more startling thing is that, as long as you keep your focus on your white speck, the change blindness will kick right back in. Knowing an illusion exists doesn't dispel its powers.

This illusion is the work of Harvard researchers Jordan Suchow and George Alvarez. The changing dots illustrate a mental phenomenon known as silencing, in which visual change suddenly becomes nearly impossible to detect. They explain:

Silencing demonstrates the tight coupling of motion and object appearance. Simply by changing the retinotopic coordinates-moving the object or the eyes-it is possible to silence awareness of visual change, causing objects that had once been obviously dynamic to suddenly appear static...This motion-induced failure to detect change, silencing, persists even though the observer attends to the objects, knows that they are changing, and can make veridical judgments about their current state.

So what's misfiring in your vision to create this effect? Suchow and Alvarez argue that it's all down to how we map out our field of vision in our heads:

To detect that a moving object is changing, the visual system must track the object's state. Presumably, the mechanisms that carry out these measurements are local-i.e., each monitors a fixed location in the visual field that corresponds to a fixed location on the retina. Because a fast-moving object spends little time at any one location, a local detector is afforded only a brief window in which to assess the changing object. This brief exposure may be insufficient to detect any changes, or perhaps insufficient to properly attribute detected changes to anything other than motion.

And silencing isn't just limited to changing colors, and the researchers have even more videos to prove it. The illusion is just as strong for brightness...



...size...



...and even shape...

[Original paper and videos]