The ‘Coffer Illusion’ has left people baffled after they were unable to see the circles in the image.

The puzzling image, called the Coffer Illusion, has proved popular on Facebook — even though most people have struggled to solve it within the 30 minute target.

The picture initially appears to be a series of sunken black and white rectangles that doesn’t feature any curved edges.

But creators sat that after a while, your brain’s representation of the image may “flip” and instead you will see 16 circles.

The illusion plays on the fact that the visual brain is heavily geared towards identifying objects that are grouped to form edges and contours.

In this case, a single set of horizontal lines can either form a circle, or be the intersection between two rectangles.

For most people, the grouping into rectangles initially dominates. This may be because rectangles (including the ones we see in door panels) are often more common than circles in our daily environment, and so the brain favours the grouping that delivers rectangular shapes.

But on closer inspection, the 16 circles will jump out at you.

And it you still can’t see it, here’s a tip — look in between each rectangle at the vertical lines.

But even then some people still really struggle to see the circles.

This article originally appeared on The Sun and is republished with permission.