Silencing is a type of optical illusion that shows it’s more difficult to notice details when objects are moving. The illusion is the work of Harvard researchers Jordan Suchow and George Alvarez, who developed the eye trick a few years back to illustrate just how easy it is to trick both the mind and the eye.

This particular “color changing dot test” was developed to illustrate silencing, a mental phenomenon where a slight change in appearance becomes nearly impossible to detect.

In order to grasp the full affect, you must first view the video while focusing on the white dot in the center of the circle. Then play the video again, this time focusing on one of the colored dots. If done correctly, you should be able to notice that the dots had been changing color the entire time. It’s just you weren’t able to notice this the first time around.

The illusion is based on the close relationship between motion and the appearance of an object. iO9 reported that by changing where your eyes are focused on a moving object, it is possible to silence the awareness of a visual change. This is because the actual motion interferes with our ability to notice change. In order for our eyes to detect that an object is changing, we must be able to tract the object’s state, Suchow and Alvarez explain.

“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,” the duo concluded.

The science behind what makes silencing work might be a bit hard to digest, but ultimately it means that motion can interfere with your perception of reality, and above all, don’t be so keen to believe everything you (think) you see.