Early history of illusions

Illusions are considered in the context of the history of vision rather than the history of psychology. For much of its long history, the study of vision has been confined to naturalistic observation, and many motion illusions were observed in the natural world. With the move to the laboratory, the oddities of visual perception multiplied, and they received ever more detailed scrutiny. This survey examines the origins of research on visual illusions in both the natural world and the laboratory. It commences with celestial illusions and pictorial representation then proceeds to subjective visual phenomena and spatial illusions like ambiguous figures and geometrical optical illusions. However, most attention is paid to motion illusions; these include visual persistence and stroboscopic motion, induced motion, motion aftereffects, visual vertigo, and autokinetic sensations. The basis for the explosion of research on visual illusions in the nineteenth century is speculated upon.