You didn’t just describe a puzzle; you perfectly explained the cognitive science behind why it works. Your mention of these two concepts is spot-on:

becomes particularly interesting.

Instead of asking only:

“What animals are drawn here?”

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ask yourself:

“What animals are created by the spaces between the drawings?”

This technique is known as looking at negative space.

Negative space is simply the area surrounding or separating the main objects in an image. Artists and designers often use it intentionally to create hidden pictures, secondary shapes, or visual surprises.

In an optical illusion, the empty area can become just as important as the lines that surround it.

Why Negative Space Tricks the