SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
Impossible trident. This uses the fact that a rectangular bar can be represented in 2 dimensions by 3 lines, whereas a cylinder requires 2. So we have 3 cylinders blending into 2 rectangular bars. The brain tries to identify the shapes but is left confused due to the ambiguities over to which part the edges belong. This object has been used to demonstrate that the visual system compares different regions through counting, since the first thing most people notice is that 2 prongs at the beginning change to 3 at the end.
Model release not required. Property release not required.