P-EYE is an eye tracking system for practicing digits of π. Users recall the digits by looking left (smaller numbers) or right (larger number).
The system generates feedback through music. An algorithm determines the pitch, the instrument that is sampled, and the number of times it is repeated.
π-Eyed began as a wearable version of PEYE that also serves to limit and control the user's perception. It was ultimately developed into a freestanding object that provides feedback through solenoid motors that strike the devices from the side.