BrightKidz Library
Subjects

The Movement That Is on None of the Pages

About 12 minutes

Take any flipbook apart and look at the pages one at a time. Page one: a ball near the bottom. Page two: a ball slightly higher. Page three: higher again.

Every page is a still drawing of a ball sitting completely still. There is no page anywhere in that stack with a moving ball on it, because a drawing cannot hold movement — it is ink that stays where it was put.

Flick the stack and the ball rises smoothly through the air.

So where did the movement come from?

Not from the pages, and not from your eye holding on

You may have heard that your eye keeps each picture for a fraction of a second after it goes, so the pictures smear into each other. It is a tidy explanation and it is not what is happening.

If your eye simply held on to old pictures, a flipbook would look like a blur — three balls at once, faintly, in three places. That is not what you see. You see one ball, sharp, in one place, going somewhere.

Blurring together and moving are different results, and the one you get is movement.

Your brain fills the gap

What actually happens is closer to a decision than a smear.

Your visual system is built to track things. Objects in the world move, and something that appears here and then almost-here a moment later is nearly always one object that travelled, rather than two objects taking turns.

So when two similar shapes appear in quick succession, slightly apart, your brain reports the far more likely story: one thing, and it moved. It builds the journey between them and hands you the finished version.

Three still pages, and the movement that is on none of them Three separate pages stand side by side on the left with clear gaps between them, so no page touches another. Each page carries a single dot, and the dot sits a step higher on each page than on the one before. Nothing on any page is moving; each is a still picture of a dot resting in one fixed place. A faint upright line divides the picture, and to the right of it a bold dashed curve climbs from low on the left to high on the right and finishes in an arrowhead. That climbing curve appears on no page at all. It is the movement a reader builds for themselves when the three still pages are flipped past the eye one after another.
Three pages, three still dots, nothing moving on any of them. The climbing curve on the right is on no page at all. It is what a reader adds when the three arrive one after another.
Three still pages, and the movement that is on none of them Three separate pages stand side by side on the left with clear gaps between them, so no page touches another. Each page carries a single dot, and the dot sits a step higher on each page than on the one before. Nothing on any page is moving; each is a still picture of a dot resting in one fixed place. A faint upright line divides the picture, and to the right of it a bold dashed curve climbs from low on the left to high on the right and finishes in an arrowhead. That climbing curve appears on no page at all. It is the movement a reader builds for themselves when the three still pages are flipped past the eye one after another.

Step through the three pages one at a time and watch what each page actually contains.

  1. Page one. A dot, low down, sitting still. Nothing here is moving.
  2. Page two. A dot, a little higher, sitting still. Still nothing moving — and this dot is not the same dot, it is a fresh drawing.
  3. Page three. A dot, higher again, sitting still. Three still pictures, no movement anywhere. The rising you can feel building is yours.

If this sounds familiar, it should. It is the same job a reader does in the white gap between two comic panels — you draw two moments and they invent the bit in between. A flipbook is that same trick run at speed, many times a second, on a gap so small you never notice you are crossing it.

The two ways to break it

Because the movement is built rather than shown, you can push it until it stops working, and both failures are worth causing on purpose.

Go too slow. Below roughly ten pictures a second the illusion collapses. Your brain stops joining them and starts reporting the truth: separate pictures, one after another. Flick a flipbook very slowly and you can feel the exact moment it gives up.

Move too far. If the ball jumps a long way between pages, the two shapes are no longer near enough to be read as one thing. You get a flicker between two different balls. Small steps read as movement; large steps read as a change of scene.

Which gives you the whole craft of animation in one sentence: small enough steps, fast enough to join.

Make one

  1. Work on the corner furthest from the staple, the part your thumb will release last. Keep every drawing in that corner.
  2. On the last page, draw a small dot near the bottom edge.
  3. Turn to the page in front of it. You should be able to see the dot faintly through the paper — draw a new one just above where it shows.
  4. Keep going, one page at a time, moving the dot a little higher each time. Twenty pages is plenty.
  5. Bend the pad, release the pages under your thumb, and watch it rise.
  6. Now make a second one where the dot jumps a long way between pages. Flick it. Compare the two. The first moves; the second flickers.

Once that works, try a dot that rises, slows, stops for two pages and falls back. Bunching the drawings closer together makes the movement slower, and spreading them out makes it faster — even though you are turning the pages at the same rate throughout.

Your flipbook character moves in awkward jerks. The drawings are all good. What is most likely wrong?

The part worth keeping

Every film, cartoon and game you have ever watched is still pictures shown quickly. Not one of them contains any movement — the movement is manufactured, every time, by the person watching.

Which makes an animator's real job an unusual one. They are not drawing movement. They are choosing exactly which still moments will make a viewer build the movement they had in mind.