Coffer Illusion
Educated people and, on average, people in the West tend to see squares first, while others more often see circles first. Just imagine, that some people only see circles, for me that's is not easy at all.
In fact, the image is simple, there are horizontal stripes with 16 circles cut out of them and rotated 90º. Because of this, some people don't notice the rectangles (often called "squares" for simplicity) formed by this arrangement and only see the cut-out circles.
Industrialization and life in cities filled with rectangular objects and buildings develop a new skill in us to recognize these newly formed rectangles. Without this skill, the circles cut out of the stripes are the natural thing to see, and because of how they're cut, the circles are what stand out.
But the skill honed to recognize the pattern of rectangular objects is so strong that people raised in an industrial environment are led to see the illusion of the formed rectangles as the main subject of the image.
Tags: psychology, perception, illusion, culture