The Subjective Nature of Objectivity
Stay still froggie or a predator might see you!
The images below appear to contain random dot patterns. These are the first frames from movie (.mpg or .mov) files which you can download by clicking on any of the images. I suggest that you configure your player to loop or recycle.
When you view each frame as a still image there is no hint of a disk shaped object. In the movie, frames are shown in rapid succession and a disc appears to bounce from left to right across the screen. The frame to frame displacement of a group of dots is sufficient disparity to cause us to organize the dots into a moving object. In the oval images above and below, the displacement is a rotation of the dots around a point.
Gestalt psychologists called grouping phenomena like this one, "Common Fate".