title: The Leaning Tower of Pisa effect: an illusion mediated by colour, brightness, and motion.
abstract: We report a novel, easily observed, and extraordinarily striking optical illusion mediated by interactions of colour, brightness, form, and motion perception--the Leaning Tower of Pisa (LTOP) illusion. Under some circumstances, the perception of orientation of coloured forms is radically altered by rotary movement. We demonstrate that this kinetic effect--easily reproduced with a common record turntable--is optimised by particular colour and brightness differences between foreground and background with an illusory tilt of 8 degrees and more. The described illusions can be easily studied at home by downloading the colour figures from www.perceptionweb.com/perc1000/ditzinger, printing them on a common colour printer and placing them on a rotating record turntable.
authors.affiliation: Center for Complex Systems, Florida Atlantic University, Boca Raton, FL 33431, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ditzinger
authors.forename: V A
authors.initials: VA
authors.lastname: Billock
authors.forename: J A
authors.initials: JA
authors.lastname: Kelso
authors.forename: J
authors.initials: J
authors.lastname: Holtz
mesh_terms: D003118:Color Perception / Q000502:physiology*; D006801:Humans; D008029:Lighting; D009039:Motion Perception / Q000502:physiology*; D009903:Optical Illusions / Q000502:physiology*