This optical illusion contains a hidden number that not everyone perceives in the same way.

What happens if you don’t see the same thing as your neighbor?
The fascinating thing about this spiral is that each person sees something different in it. It’s not a brain defect, but simply a combination of several factors:
Your visual sensitivity: Some eyes are more adept at perceiving subtle contrasts. It’s not a matter of good or bad vision, but of individual sensitivity.
The quality of the screen: brightness, contrast, resolution… A recent screen will display more detail than an older model or a worn-out tablet.