Motion - Timing.
Linear motion looks fake. Nothing goes from rest to full speed in a single frame. Everything that moves speeds up, then slows down. Keyframes say where, the curve says how: the module shows a movement and its speed curve side by side, from the eight basic profiles to the most common type moves.
Acceleration and deceleration
Starts from rest and comes back to it. The default profile of a believable gesture.
Don't look at the position, look at the speed. The height of the curve is the speed at that moment; its shape is the intent of the motion.
The ticks above the ball are the 25 frames of the second. Close together, the object slows down. Far apart, it races.
Glossary
- Timing
- The duration of a movement, counted in frames. At 25 frames per second, a one-second gesture takes 25. The same distance in 10 frames feels lively; in 50 it feels heavy.
- Spacing
- The distance travelled from one frame to the next. Close positions slow the object down, wide ones make it race. That's what the ticks above the ball show.
- Linear motion
- A speed that never changes. It's the only profile you never meet in nature, and it looks fake.
- Acceleration, deceleration
- Speed building at the start, then dropping before the stop. Nothing goes from rest to full speed in a single frame: everything that moves speeds up, then slows down.
- Squash and stretch
- The object squashes on impact and stretches in the fall, without changing volume. One of the twelve principles of animation described by Frank Thomas and Ollie Johnston (The Illusion of Life, 1981).
- Overshoot
- The motion goes slightly past its final position, then settles back in a few frames. It gives momentum and weight.
- Anticipation
- A small move in the opposite direction before the main action: the eye is warned. One of the twelve principles of animation.
- Stagger
- The same motion repeated across several elements, letters or layers, a few frames apart. In a text Animator, the Offset of the Range Selector makes it travel.
- Onion skin
- Neighbouring frames shown transparently around the current one, so the spacing can be read at a glance.
- Frame rate
- The number of frames per second: 25 in Europe for television and advertising, 24 in cinema.
- Graph Editor <span class="mtm-gae" title="After Effects">Ae</span>
- The timeline view where you adjust curves rather than values (Shift + F3). It shows either the value graph or the speed graph: you choose in the graph type menu at the bottom of the editor.
- Speed graph
- Speed over time. The height of the curve is the speed at that moment; its shape is the intent of the motion. At 0, the object is still.
- Value graph
- The value of the property over time: position, rotation, opacity. It shows where the object goes, less clearly at what pace.
- Bézier handle
- The lever coming out of a keyframe in the editor. Its height sets the speed at the keyframe, its length sets the influence.
- Influence <span class="mtm-gae" title="After Effects">Ae</span>
- The length of the handle, as a percentage of the time to the neighbouring keyframe. The longer it is, the more violent the profile. Easy Ease sets 33.33% on each side.
- Speed profile
- The shape of the curve between two keyframes. Eight profiles cover almost everything you animate: linear, acceleration, deceleration, both in a row, and their extreme versions.
- Keyframe
- A value fixed at a point in time. Keyframes say where; the curve between them says how.
- Stopwatch
- Nothing animates while it's off. Twirl down the layer, find the property (position, rotation, scale or opacity) and click the stopwatch: the first keyframe lands there.
- Interpolation
- How the frames between two keyframes are calculated. The keyframe's shape tells you which: the left half describes how you arrive at the keyframe, the right half how you leave it. A point facing outward is linear, a point facing the centre is eased.
- Temporal, spatial
- Temporal interpolation sets the speed: that's the speed graph. Spatial interpolation sets the path in the frame, straight or curved. An animation can be perfectly eased in time and still follow an angular path.
- Linear
- The diamond. Constant speed from start to finish. It's the keyframe the stopwatch sets.
- Hold
- The value stays frozen until the next keyframe, then jumps. Cmd + Option + click the keyframe (Ctrl + Alt + click on Windows).
- Auto Bezier
- The circle. Smoothed on both sides, calculated by the software. Cmd + click the keyframe (Ctrl + click on Windows); the same gesture turns it back to linear. Touching a handle turns it into Continuous Bezier.
- Easy Ease
- The hourglass. F9: zero speed at the keyframe, 33.33% influence. Each half exists on its own: Easy Ease In (Shift + F9) and Easy Ease Out (Cmd + Shift + F9, Ctrl + Shift + F9 on Windows).
- Keyframe Assistant
- The right-click submenu on a keyframe that groups the eases.
The eight speed profiles
Linear. Speed never changes. It's the only profile you never meet in nature.
Deceleration. Sharp start, soft landing. The gesture sets off fast and settles.
Sharp deceleration. Almost everything happens in the first frames. An impact, a snap.
Acceleration. Slow start, fast finish. A heavy mass getting going.
Extreme acceleration. Nothing happens, then everything at once. A suction, a fall.
Acceleration and deceleration. Starts from rest and comes back to it. The default profile of a believable gesture.
The spike in the middle. Everything happens in a few frames. A flash past.
Rise then hard stop. The motion builds, reaches its peak, and cuts.
After Effects keyframe shapes
Linear. Constant speed from start to finish. It's the keyframe the stopwatch sets.
Hold. No interpolation: the value jumps. Cmd + Option + click the keyframe (Ctrl + Alt + click on Windows).
Auto Bezier. Smoothed on both sides, set on its own. Cmd + click the keyframe (Ctrl + click on Windows). The same gesture turns it back to linear.
Easy Ease. Gradual start, cushioned arrival. F9, or right-click > Keyframe Assistant > Easy Ease.
Easy Ease In. Cushioned arrival, linear exit. Shift + F9, or right-click > Keyframe Assistant > Easy Ease In.
Easy Ease Out. Linear arrival, cushioned exit. Cmd + Shift + F9 (Ctrl + Shift + F9 on Windows), or right-click > Keyframe Assistant > Easy Ease Out.
Type motion
Overshoot. The word slides in, overshoots its place by a few pixels and settles back in three or four frames. Overshoot gives momentum and weight. Three position keyframes: the start, one slightly past the final position, then the final position three or four frames later, eased (F9).
Damped bounce. Several back-and-forths, each smaller, before it settles. More playful: keep it for light subjects. One keyframe per bounce, each closer to the final position and closer in time. A bounce expression on the property does the same without keyframes.
Slide in. The word arrives fast and brakes into place. It's the most common type move. Two position keyframes, the second with Easy Ease In (Shift + F9). Lengthen its influence in the Graph Editor for a stronger brake.
Scale pop. The word grows from a point, gets slightly too big, then settles: 0%, 110%, 100%. Three scale keyframes a few frames apart: 0%, 110%, 100%. Ease the last two.
Letter by letter. The same move for each letter, offset by two frames. The word reads like a wave. On the text layer, Animate > Position adds an Animator. Give it a vertical offset, then animate the Offset of its Range Selector: the move travels from letter to letter.
Typewriter. The letters appear one by one, all at once, with no transition. An Opacity animator at 0% whose Range Selector you move forward, or Hold keyframes. The Typewriter animation preset does the same.
Anticipation. A small step back before leaving. The eye is warned, and the exit feels stronger. It's one of the twelve principles of animation. One more keyframe just after the start, a few pixels in the opposite direction, then an accelerating exit: Easy Ease Out (Cmd + Shift + F9) on that keyframe.
Whip. The word crosses the screen in a few frames: almost the whole trip happens in the middle. Motion blur does the rest. Two eased keyframes, influence pushed to 80 or 90% in the Graph Editor, and motion blur switched on for the layer and the composition.
Mask reveal. The word rises from behind an invisible line: it doesn't appear, it comes out from somewhere. A shape layer used as an alpha track matte above the text (or a mask), and a vertical slide in with deceleration.
Sources: the course pack Du brief au master (Xavier Reyé, 2026), pages 41 to 43 · Frank Thomas & Ollie Johnston, The Illusion of Life: Disney Animation (1981), for squash and stretch and anticipation · Adobe After Effects: keyframe interpolation and keyboard shortcuts, checked in November 2026 (Mac shortcuts, Windows in brackets).
Ten questions: four movements to match with their curve, six on the Graph Editor, keyframes and type.
