- One of the most useful concepts for understanding optical illusions is negative space.
Negative space refers to the areas surrounding and separating visible objects.
In an ordinary picture, we tend to concentrate on the objects themselves.
We notice the animal rather than the empty space beside it.
We examine the tree rather than the gaps between its branches.
But artists can use those apparently empty spaces to create additional shapes.
A gap between branches might suggest a facialfeature.
A curved boundary could resemble part of a head.
Several disconnected
