Figure 1. Anisotropy of a rotating ring illusion videos.

A: Two Styrofoam rings glued together at an angle are seen to rotate together on the turntable (see Figure S1A). B: When rotated 90°, one ring appears to move independently and wobble against the ring on the turntable (see Figure S1B). C & D: Two circular (C) and octagonal (D) rings physically rotate together with a fixed connection at the junction (see Figure S1C and Figure S1D). E & F: The two pairs of rings physically move independently and wobble against each other. For the circular rings, E is indistinguishable from C. However, with trackable vertices, F is discernable from D (see Figure S1E and Figure S1F). G & H are the same as C & D except that they are rotated 90° and they both look nonrigidly connected (see Figure S1G and Figure S1H).