Published: April 9, 2025 | Last Updated: April 11, 2025
PERSISTENCE OF VISION DEFINITION & MEANING
Persistence of vision is the optical phenomenon where multiple still images shown in rapid sequence appear as a continuous moving image. Our brains blend those images together because the eye retains each one briefly, making motion possible in film, animation, and video. It’s also what allows for light painting, e.g., when you spell a name or draw a circle or heart with a sparkler.
How persistence of vision works
When you watch animation or film, you’re not seeing motion—you’re seeing still images shown so quickly that your brain connects them. The human eye retains an image for about 1/16th of a second. If the next image appears during that time, the two blur together.
This effect tricks us into perceiving movement even though nothing is actually moving on the screen. It’s the foundation of all animation, from flipbooks to 24fps cinema to digital 3D rendering.
Why 24 frames per second became the standard
Early experiments showed that around 10–12 images per second created flicker-free continuity.
However, 24fps became the standard for motion picture film because it balanced smooth motion with sound sync requirements and economic limitations.
At 24fps, persistence of vision hits its sweet spot—movement feels real, and the illusion is seamless. That’s also why most 2D animation uses techniques like:
- Animating on ones: One unique image per frame (24 drawings per second). Used for fast or smooth motion.
- Animating on twos: One drawing every two frames (12 drawings per second). Used for most character animation to save time while maintaining flow.
- Animating on threes: One drawing every three frames (8 drawings per second). Common in anime or stylistic sequences where minimal motion is offset by strong composition or emotion.
Early optical devices that used persistence
Before film existed, scientists and artists experimented with devices that exploited persistence of vision:
Phenakistoscope (1830s): A spinning disc with sequential images viewed through slits, creating the illusion of motion.
Zoetrope: A cylindrical version with images inside or figurines inside. Spinning it showed a moving animation loop.
Flipbooks: Flipping sequential drawings shows fluid action—basic persistence of vision in your hands.
Scientific background
Peter Mark Roget originally described persistence of vision in the 19th century as an eye-based defect, where a fast-spinning object appeared still. Later theories corrected this. The effect happens not just in the retina, but in how the brain processes continuous visual input.
German psychologist Max Wertheimer studied how the brain interprets quick sequences as motion, developing theories that led to modern understandings of visual perception. Today, it’s clear that motion perception is a product of both image retention and neural processing, not just “afterimages” in the eye.
How it affects animation choices
Understanding persistence of vision helps animators decide how many drawings they need per second and what level of fluidity is needed for each moment.
For action scenes, animating on one provides crisp movement. For dialogue or subtle gestures, twos are often enough. Animation is expensive and time-consuming, so getting the most out of the illusion is part of the craft.
Summing up
Persistence of vision is why still images look like they’re moving. It’s the invisible trick that makes animation, cinema, and video work. By understanding how the brain retains and processes visuals, artists and filmmakers turn static drawings into kinetic stories, one frame at a time.
