The stage hypnotist's converging spiral and its relatives — rotating patterns that mimic
endless motion, fatiguing direction-selective cells in your visual cortex. Afterwards,
stationary objects briefly appear to swirl. Pure theater… mostly.
⚠️ Photosensitivity note: several of these are high-contrast, repetitive patterns.
If you are sensitive to flashing or rotating patterns (or have photosensitive epilepsy),
please skip them. 30–60 seconds of viewing is plenty for the after-effects.