2. The horizontal lines in this image are all parallel. https://t.co/Y0o0hd8R15 HT @victoria1skye pic.twitter.com/Sp1JoPGzsb

— Steve Stewart-Williams (@SteveStuWill) October 11, 2018

4. This isn't a GIF – the movement is all in your head. pic.twitter.com/8A9pJigPri

— Steve Stewart-Williams (@SteveStuWill) October 11, 2018

6. We don't directly perceive how light or dark objects are; the perceptual system makes an educated "guess" based on the lightness or darkness of the surroundings. https://t.co/C8VwDBJbYx HT @AkiyoshiKitaoka pic.twitter.com/Uo3U291WLw

— Steve Stewart-Williams (@SteveStuWill) October 11, 2018

8. The Dynamic Müller-Lyer Illusion: The vertical black, green, and blue lines don't change size. https://t.co/bDyeOKXgbC pic.twitter.com/duaY20axxE

— Steve Stewart-Williams (@SteveStuWill) October 11, 2018

10. Rotating Rings: Every time you switch from looking at one wheel to looking at the other, they both change direction. https://t.co/IdAQGgXsJi pic.twitter.com/682GbM9KyK

— Steve Stewart-Williams (@SteveStuWill) October 11, 2018

12. Stare at the centre of the top image for 20 seconds then look at the bottom image… pic.twitter.com/l40EbUBwIL

— Steve Stewart-Williams (@SteveStuWill) October 11, 2018