In the above image we see a square. However, there is no square in this image since there are no four equally long line segments with 90° angles between them. The picture just shows four incomplete black discs that look like Pac-Man figures.

We see a square because we recognize a square. We recognize a square because the picture implies a square. The picture implies a square because it contains enough characteristic features of a square. These characteristic features are sufficient for us to recognize a square because we are familiar with squares. We are familiar with squares because we have seen countless squares and other rectangular shapes in our life such as books, boxes, tiles, doors, rooms, and houses. The civilized world is full of rectangular objects. Living in this world conditions one to see rectangular shapes.

We perceive what we have learned to perceive. It needs curiosity and effort to perceive the truth. Try to see only four Pac-Man figures and no square!

More in my book “Consciousness: Its Nature, Purpose, and How to Use It.”