Abstract

Animation is based on a simple optical principle: showing still images fast enough makes the brain perceive motion. This phenomenon, known as persistence of vision, helps explain how drawings and frames can appear to move. This article explains what persistence of vision is, how simple devices from the 19th century used it, and how modern animators apply it to create moving characters and scenes. It also introduces key terms such as “frame rate”, “keyframe”, and “timing” in a way that is accessible for high school students exploring university animation programs. Understanding this foundational concept gives insight into why 2D animation works and what you will learn if you decide to study it further.

Keywords: animation, persistence of vision, frame rate, keyframe, 2D animation, timing, illusion of motion

What is persistence of vision

Persistence of vision describes how the human eye and brain retain an image for a short amount of time after the image has disappeared. The Peter Mark Roget definition from the nineteenth century says that the retina holds the afterimage briefly, so that when a new image appears soon after, the two overlap in our perception. (adobe.com)

Because of this, when we view a sequence of still images fast enough, our brain blends them into what appears to be smooth motion. (rebusfarm.net)

Early examples of animation-type devices

One of the first simple devices that used this idea is the thaumatrope, a spinning disc with different drawings on each side. When spun, the two images merge in our vision because of the afterimage effect.

Another device is the zoetrope: a cylinder with vertical slits and a strip of pictures inside. As it spins and you look through the slits, successive drawings appear to move. (fiveable.me)

These devices show that the principle of motion illusion has been used long before digital animation, and help you see why animation works.

Frame rate and timing

In animation, “frame rate” means how many still images (frames) are shown each second. If the number of frames is too low, motion appears choppy; if high enough, it looks smooth. For example, showing 24 frames per second (fps) in film is common because the eye perceives it as continuous motion. (studiobinder.com)

“Timing” is how long a movement takes: for instance, if a character takes two seconds to raise an arm or one second. What the animator chooses affects how we interpret the action. A quick raise might feel sharp or excited; a slow raise might feel hesitant or calm.

These terms link together: an animator draws keyframes (main positions) and then fills in between them (in-betweens) so that when frames are played at the right rate the motion appears fluid.

How modern 2D animation uses the principle

Even though the tools are digital today, the principle remains: a series of slightly changing drawings is played back fast enough to give the sense of motion. Traditional hand-drawn cells are now often replaced or supplemented by digital drawings, but timing and frame rate are still crucial.

ccording to Adobe’s explanation, persistence of vision is “the core reason why animation works in the first place.” (adobe.com)

An animator might choose to draw fewer frames (“on twos,” meaning one drawing per two frames) for slower motion, or every frame (“on ones”) for fast motion. (studiobinder.com)

Understanding this helps you when you learn to animate: you will practice drawing key poses, then in-between them, and choose how fast or slow each movement happens.

Why this matters for a high school student considering animation

If you are thinking of studying 2D animation at university, knowing how movement illusions work gives you a head start. You will begin with simple exercises: drawing a bouncing ball, flicking a flipbook, or sequencing a motion. These teach you timing, spacing, and frame rate — the building blocks of animation.

When you move on to character animation, you’ll apply these ideas to more complex motion: a character walking, turning, or reacting. The same principle (sequential frames and correct timing) gives the motion its lifelike quality.

By knowing that animation relies on how our brain processes visual information, you gain insight into why an action looks natural or jarring. That awareness helps you create better work and understand what you will be taught in university courses.

How you can experiment now

Try this: draw a simple flipbook—say, a circle that moves across the page. Flip the pages quickly and watch how it seems to move rather than appear static. Then vary how many drawings you use: five drawings over ten pages versus five drawings over twenty pages. Notice how the motion feels slower or faster.

In digital tools or traditional paper, practice keyframe/in-between workflows: draw a character in pose A and pose B, then draw three or five drawings in between, and play them at about 12–24 fps. This shows how timing and spacing affect the illusion of movement.

The illusion of motion that underpins animation starts in how our eyes and brain perceive still images in rapid sequence. By understanding persistence of vision and related concepts like frame rate and timing, you can begin to grasp the underlying technique of 2D animation and get ready for what you will learn at university.