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

Four examples of the uniformity illusion with orientation 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).
  • The first two examples contain no fixation spot, the latter two are identical to the first two, but they do contain a fixation spot. Some people find that the illusion works better without a fixation spot, but you can try out which works best for yourself. 
  • 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 lines in the background all have orientation of 20 or 60 degrees, when the central lines have orientations of 45 degrees, all lines seem to take on this orientation; and when the central lines have orientations of 35 degrees, all lines appear to take on an orientation of 35 degrees.