Motion From Flashes
You will see two brief visual events that alternate on the screen. Watch the display and decide whether you experience two separate flashes or a single object moving between two positions.
You can then adjust the timing and spacing to see how the appearance changes.
This is a browser-based teaching demonstration, not a calibrated laboratory experiment.
What do you mainly experience?
What happened?
Your response
Physical display
No object actually travelled across the screen. One dot appeared briefly in one position, disappeared, and then another dot appeared briefly in a different position.
What this demonstrates: under some timing conditions, successive flashes at different locations are experienced as continuous motion. This is known as phi motion or apparent motion.
The demonstration shows that perceived motion is not simply a direct copy of a moving object in the world. Motion can be constructed by the visual system from a sequence of discrete events over time.
In a formal experiment, timing, luminance, viewing distance, stimulus size, and refresh rate would need to be precisely controlled. This version is intended for teaching and public engagement.