Quick Answer: The Parrot in Cage Model STEM Lab demonstrates persistence of vision with a balanced disc showing a parrot on one face and a cage on the other; spun fast on its belt-driven mount, the two pictures merge into a parrot inside the cage.
Last updated: October 2026
Key Features
Two-sided disc: parrot on one face, birdcage on the other
Matte laminated graphics to cut glare
Pulley and belt drive turned by hand crank
Steel ball bearings for long spin-down
Supplied with the rotating assembly, target discs, drive belt and guided workbook
At rest the parrot and the cage are seen separately; turned slowly, at 1 to 2 rotations per second, the two flicker in turn. Above about 16 picture changes per second the eye can no longer separate them and the parrot appears inside the cage, which explains how film, animation and screen refresh rates give smooth motion.
Frequently Asked Questions
At what speed does the parrot appear in the cage on the Parrot in Cage Model STEM Lab?
Once the disc gives more than about 16 picture changes per second, the two images merge; at 1 to 2 rotations per second they still flicker separately.
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