blivit

Blivet is an optical illusion and an example of an impossible object. In its most familiar form, a black-and-white line drawing depicts a three-pronged fork with cylindrical prongs at the top that appear to transform into two rectangular prongs at the bottom. The conflicting cues of perspective and depth make the shape seem to exist in two incompatible ways, creating a paradoxical figure that cannot exist in three-dimensional space.

Origins and naming of the term are uncertain. The blivet has circulated in puzzle collections, cartoons, and discussions of visual perception since the mid-20th century, and it has taken on several names such as the devil’s fork or the impossible trident. As with many optical illusions, the exact source of the image is difficult to trace, but it has become a standard example in studies of perception and cognitive psychology and in discussions of non-Euclidean or ambiguous figures. The concept is closely related to other famous impossible objects, such as the Penrose triangle and Escherian stairs, though the blivet is typically presented as a flat drawing that challenges the viewer’s interpretation of depth.

Variations of the blivet exist, with different prong shapes or connects, but the core illusion—prongs that cannot coherently attach to a single three-dimensional form—remains the essential feature. The image continues to appear in books, magazines, and online collections as a simple, accessible illustration of how visual cues can be misleading.