To the lecture series English top page

Comments on Lecture 3 "Height-Reversing Staircase"

Comment 1. Trick of the color change of the car

In the mirrir image, not only the orientation of the staircase changes but also the color of the car changes. This is because the car we see in the mirror is different from the car we see directly. Actually there are two cars, one is red and the other is green. The main object including the staircase is a horizontal picture, but it is not placed on the desk surface directly. It is placed a little higher than the desk surface. So it can hide one of the cars behind. We changed the desk surface to black in this scene; this is because the shadow casted on the desk surface is less visible and it is relatively difficult to recognize the real height of the picture. (Please note that this color change is not optical illusion; it is just a trick like magic.)

Comment 2. For those who want to construct the height-reversing staircase

The first object shown in the lecture is the left picture. Copy it, cut it along the boundary, rotate it by 45 degrees clockwise and place it horizontally in front of a vertical mirror. Then you can enjoy the illusion of the height-reversing staircase. If you close one of your eyes, the illusion will become stronger.

Comment 3. Reference on the height-reversing staircase

K. Sugihara: Height reversal generated by rotation around a vertical axis. Journal of Mathematical Psychology, vol. 68-69 (2015), pp. 7-12.