That man isn't actually screaming in horror -- those wires are electrodes, and he's making that expression because electrical currents are contorting his facial muscles against his will. Okay, he may also be screaming in horror.
The mutton chops on the right there belong to Guillaume-Benjamin-Amand Duchenne, a French neurologist who electrocuted the **** out of a mental patient's head meat to make him pull goofy faces, and then photographed those faces in the pursuit of knowledge. Consequently, it looks like a still from Howdy Doody if Howdy was the taxidermied corpse of a homeless man rigged with the same wires they used to make Mr. Ed speak.