OpticalDose

This wearable app allows you to take instant doses of an effective optical illusion.

As soon as you launch the app, a black-and-white GIF starts playing and, as you focus on the center of your wearable screen, a waterfall illusion might be triggered and you'll see things around you moving.

You just need to look at your screen for a few seconds and you'll start feeling the motion aftereffect provoked by the Phi phenomenon.