1. Optical illusions These are interesting since we may have similar perception problems as we read our exams

2. None of these below are actually moving

6. The horizontal lines are parallel

7. These are not spirals, but circles !

8. After some time you may not see the pink dots anymore, just the moving green dot. Focus on the + sign, note the appearance of a moving green dot

9. Fixer le point central en se rapprochant de l’écran puis en s’éloignant Focus on the central dot and move closer and away from the screen