The experiment was carried out by Giovanni Aldini, who, by the time he zapped Forster in public, had not only mastered his core technique, but developed a theatrical flair. First, he applied the electrified conducting rods to Forster's face, which caused Forster's jaw to quiver and grimace horribly. His left eye popped open. Aldini then applied the rods to Forster's torso, causing the body to jiggle and contort and even blow out a candle. What, you couldn't flex the jaw and make it talk in a funny voice? The audience had to have been disappointed by that, but way to show some restraint there.
Wait, we take that back. Because nothing could have prepared audiences for the grand finale, in which Aldini shoved a conducting rod into the cadaver's rectum, causing it to punch a fist in the air (really, this is the type of climax that no one is prepared for).
"You keep your eyes open, people. This is the world."
Aldini continued touring with his show, but only used decapitated heads, presumably because they're much easier to travel with. His experiments would ultimately inspire Mary Shelley to write Frankenstein, which may explain why the monster staggers around like it has a stick up its ass.