Visual Seal

A baby's eyes don't work the same way as an older child's. They are less precise, can't make out small details and can't follow pictures that move quickly. That's why we need a set of rules that the AI assistants must follow to draw suitable pictures for each age group. The Visual Seal is our way of setting these rules: how the pictures look and move, and how they adapt to each child's eyes.

The pictures

There is always a music box, with its crank, centred and clear: that's what makes them recognisable.
Characters that seem to come in or out of the music box, or that fly above it.
Nothing scary, no aggressive expressions and no letters.
For babies and toddlers, dark, warm backgrounds: never white or blue.

The movement

Gentle and predictable: no jumps, and it always returns to where it started.
Never more than 3 sudden changes of light per second (the international accessibility standard, WCAG).
The picture moves as a whole, in one piece.
It goes with the music, it doesn't compete with it.
If the device has "Reduce Motion" turned on, the music box respects it.

The background colours, and why, are explained in The colours.

For each age

	Baby	Toddler	Child
Picture	Big, simple shapes, high contrast	Familiar objects and animals	More detail and small scenes
Movement	Very slow: rocking, breathing, slow turning	Calm	Livelier, never hurried

Speed

For a young child's eyes, what matters is not how far the picture goes, but how fast it moves. So the music box looks at the fastest-moving point of the picture, whether it is moving, turning or changing size, and compares it with the speed a child can follow with their eyes. It is measured in degrees of the field of view per second, with the device about 40 cm away.

	Baby	Toddler	Child
Maximum speed	7.5 degrees per second	15 degrees per second	30 degrees per second

If an animation is faster, the music box slows it down: the movement keeps its shape, but goes more slowly. And the picture never leaves the screen.

What the studies say

Studies measure how fast a moving object can be and a baby still follow it smoothly with their eyes:

Age	What they follow well
First weeks	About 7.5 degrees per second
1 to 4 months	8 to 32 degrees per second, less precisely than an adult
2 to 6 months	Tracking matures very quickly
6 months	Almost like an adult, up to 30 degrees per second

If the object is faster, the eyes lose it and catch up in jumps. The studies don't say which speed calms a child: they say how fast they can follow without effort. The music box stays below that. This is why the child's age matters: with the age in weeks or months, the movement can be adjusted even better.

Sources

Kremenitzer et al. (1979). Smooth-pursuit eye movements in the newborn infant. Child Development.
Lengyel et al. (1998). Smooth pursuit in infants from 1 day to 16 weeks.
Phillips et al. (1997). Smooth pursuit in 1- to 4-month-old human infants. Vision Research.
von Hofsten and Rosander (1997). Development of smooth pursuit tracking in young infants. Vision Research.
Pieh, Proudlock and Gottlob. Smooth pursuit in infants. British Journal of Ophthalmology.