Flicker

nothing on this screen has ever moved.

a marquee of chasing bulbs and a speed fader: run it fast and a light races round; hold to freeze it and nothing moved

Every bulb stays in its socket and only switches on or off; a third are lit at once and the pattern shifts one bulb per step. Slow, you see bulbs blink. Faster, your visual system links each light to the nearby one that lights next and reports one light running: apparent motion, the phi phenomenon. Film and every screen use the same trick.

Concepts: perception, motion.

An interactive you play with one thumb, on Wundr.