Animation that demos moving contrast

This came past in my twitter stream:
https://twitter.com/InertialObservr/status/1225508300290248710


alt = An animation with a black and white vertically striped background. A dark blue block and light yellow block mov horizontally across the stripes.
It looks like the two blocks are ‘stepping’ across the screen, i.e. one moves forward then the other.
When the background fades to grey, you see that the blocks are actually moving forward at a constant speed, staying exactly in line with each other.

The illusion comes from the lack of contrast with blue on black and yellow on white, so when a block meets an area of low contrast it appears to stop moving.

Not a bad analogy of why high-contrast focus indicators are easier to follow… or do I just have WCAG on the brain??

Kind regards,

-Alastair

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www.nomensa.com<http://www.nomensa.com/> / @alastc