system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why do crash test dummies have those black and yellow checkered circles on them?
gpt
The circle serves as a reference point to track how the dummy moves in a crash. It can be hard to tell a cheek from a chin in a video of a featureless dummy disintegrating, but if you have a brightly colored, high-contrast reference point it becomes much easier to track, for example, the movement of the dummy's head upon impact.