30 The MllerLyer Illusion Which line is longer

30. The Müller-Lyer Illusion Which line is longer? The top horizontal line (with arrow heads pointing inwards) appears to be longer than the bottom horizontal line (with arrowheads pointing outwards). However, they are in fact the same length. www. mastermathmentor. com It is thought that the inwardpointing arrowheads gives our brain an appearance of greater length of the lines. But it happens with circles too. In the 3 -D world, we use angles to judge depth and distance. We have grown accustomed to seeing corners everywhere. The brain is used to viewing such angles and interpreting them as far and near corners, and also uses this information to make size judgments. When looking at the Müller. Lyer arrows, the brain interprets them as far and near corners, and overrides the retinal information that says both lines are the same length.

31. The Shaking-Head Illusion Can you see anything “between the lines? ” Dr Michelle Dickinson, a nanotech engineer posted the illusion on Twitter in early 2019 with the advice: “You can only see this optical illusion if you shake your head (I’m serious)” vigorously left and right. It went viral on the Internet. You can also possibly see it if you squint. Here are 2 more, one obvious and the other very subtle. If you are viewing this in a classroom, you might have no problem seeing the image because of the distance you are to the screen. The closer you are to the screen, the more problems you will have. www. mastermathmentor. com Why does this happen? The high contrast between the black and white lines is causing our perception to overlook the mild mid-tones in the white spaces. Our visual system often responds much stronger to sharp contrasts than to gradual changes.

32. Enigma Illusion This is called the Enigma by the Israeli painter Isia Levuiant, 1995. When you stare at the center of the figure for a while, you will see a circular rotation within the violet rings as if things are running around in circle. It’s all in your mind. www. mastermathmentor. com

33. Vanishing Dots Illusion There are 12 black dots in this image. But you cannot see them all at the same time. Fix your gaze on one of the dots and then shift your gaze in small steps towards the next one. About halfway there, it becomes visible. www. mastermathmentor. com

34. Ebbinghaus Illusion You see a ring of large blue disks around an orange disk. The blue disks change size. It seems that the orange disk is changing size as well with it being largest at its location at the bottom right. The illusion is enhanced when you fix on the dot on the top left blue disk. A pair of parallel lines appears to indicate that the orange disk has constant diameter throughout. But the illusion is so strong that the lines seem to bulge. The surrounding smaller or larger blue disks affects our judgement of size. www. mastermathmentor. com

Sources 30. Muller-Lyer - https: //www. illusionsindex. org/ir/mueller-lyer 31. Shaking Head - https: //www. insider. com/optical-illusion-hidden-animal-shake-head-2019 -1 32. Enigma - https: //michaelbach. de/ot/mot-enigma/index. html 33. Vanishing Dots - https: //michaelbach. de/ot/lum-Ninio. Dots/index. html 34. Ebbinghaus - https: //michaelbach. de/ot/cog-Ebbing. Dyn/index. html www. mastermathmentor. com