Visual perception begins with our retinas locating the edges of objects in the world. Downstream neural mechanisms analyze those borders and use that information to fill in the insides of objects, constructing our perception of surfaces. What happens when those borders—the fundamental fabric of our visual reality—are tweaked? Our internal representation of objects fails, and our brain's ability to accurately represent reality no longer functions. Seemingly small mistakes lead to the very distorted perceptions of an illusory world.
Further Reading
Brightness Induction and the Café Wall Illusion. M. E. McCourt in Perception, Vol. 12, No. 2, pages 131–142; 1983.
Shifts of Edges and Deformations of Patterns. B. Pinna and R. L. Gregory in Perception, Vol. 31, No. 12, pages 1503–1508; 2002.
This article was originally published with the title "Your Twisted Little Mind" in SA Special Editions 22, 3s, 22-25 (September 2013)
doi:10.1038/scientificamericanillusions0913-22
ABOUT THE AUTHOR(S)
Stephen L. Macknik is a professor of opthalmology, neurology, and physiology and pharmacology at SUNY Downstate Medical Center in Brooklyn, N.Y. Along with Susana Martinez-Conde and Sandra Blakeslee, he is author of the Prisma Prize-winning Sleights of Mind. Their forthcoming book, Champions of Illusion, will be published by Scientific American/Farrar, Straus and Giroux. Follow Stephen L. Macknik on Twitter Credit: Sean McCabe
Susana Martinez-Conde is a professor of ophthalmology, neurology, and physiology and pharmacology at SUNY Downstate Health Sciences University in Brooklyn, N.Y. She is author of the Prisma Prize–winning Sleights of Mind, along with Stephen Macknik and Sandra Blakeslee, and of Champions of Illusion, along with Stephen Macknik. Follow Susana Martinez-Conde on Twitter Credit: Nick Higgins
