Believed to be the first animation device, the phenakistoscope was invented in 1832.? Sequenced images circle a disc with corresponding slits?. ?The viewer peers through the slits whilst spinning the disc to see the animation reflected in a mirror?. ?The phenakistoscope is based on the phi phenomenon which refers to an optical illusion wherein the brain conjures a fluid animation between separate images in motion?. ?The slits prevent? ?the images from blurring together and presents the illusion of a single moving picture?.