At first glance, the winter scene appears almost completely ordinary. Snow covers the forest floor, tall trees disappear into the pale distance, and a deer stands prominently among the frozen landscape. Because the animal is so recognizable, your attention naturally locks onto it first. That obvious subject, however, is what makes the puzzle challenging. Somewhere beyond the deer, a human face has been carefully concealed within the landscape, blending into the trunks, branches, shadows, and patches of snow.

The trick is to stop searching for an actual drawing of a face. Instead, examine the entire picture as a collection of shapes. Look carefully at the spaces between the trees, where dark branches cross lighter areas and where snow creates unusual outlines. Some features appear only when several separate objects are viewed together. The brain automatically tries to organize familiar patterns, which is why the hidden image can remain invisible even when you are looking directly at it. But once you notice the first unmistakable feature, the rest of the face begins to emerge…