More information: Otten, Pinto, Paffen, Seth & Kanai (in press). The Uniformity Illusion: Central stimuli can determine peripheral perception. Psychological Science

Two examples of the uniformity illusion with size as an example. 
  • Open the video fullscreen.
  • Keep your eyes fixated on the centre of the screen for a good amount of time (tens of seconds to minutes).
  • Note, depending on your screen size and your distance to your screen, this illusion may even work without making the example full screen.
For more information, see the text below the examples.

More information
Although the periphery is the same in both cases, the circles there appear to become larger when the central stimuli are larger, and smaller when the central circles are smaller.