Theories Cognitive Psychology 10 Cool Optical Illusions and How Each of Them Work By Kendra Cherry Kendra Cherry Facebook Twitter Kendra Cherry, MS, is an author and educational consultant focused on helping students learn about psychology. Learn about our editorial process Updated on March 17, 2020 Fact checked Verywell Mind content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Emily Swaim Fact checked by Emily Swaim LinkedIn Emily is a board-certified science editor who has worked with top digital publishing brands like Voices for Biodiversity, Study.com, GoodTherapy, Vox, and Verywell. Learn about our editorial process Print Optical illusions, more appropriately known as visual illusions, involve visual deception. Due to the arrangement of images, the effect of colors, the impact of the light source, or other variables, a wide range of misleading visual effects can be seen. If you've ever struggled to see the hidden image in a single-image stereogram, you may have discovered that not everyone experiences visual illusions in the same way. For some illusions, some people simply are not able to see the effect. Optical illusions can be fun and fascinating, but they can also tell us a great deal of information about how the brain and perceptual system function. There are countless optical illusions out there, but here is a sampling of some of the most fun and interesting. 1 The Hermann Grid Illusion Rob Patrick Robpatrick / Flickr CC Sometimes we see things that aren't really there, and the Hermann Grid illusion is a great example of this. Notice how the dots at the center of each intersection seem to shift between white and gray? Like many optical illusions, different theories have been proposed to explain exactly why this happens. 2 The Spinning Dancer Illusion The popular illusion made the rounds on blogs and websites a few years ago, supposedly as a test to determine if you are "left-brained or right-brained." In reality, the illusion occurs because our brains must attempt to construct space around the spinning figure. 3 The Ames Room Illusion Mosso - http://www.flickr.com/photos/39325045@N00/355613728/ Would you be surprised to learn that the two people in the image at the left are actually the same size? Learn more about how this classic illusion works and how the effect has been put to use in special effects such as in the movie The Lord of the Rings. 4 The Ponzo Illusion Wikimedia Commons When you look off into the distance, objects seem closer together as they become further away. For example, the outside borders of a road or railroad appear to converge as they recede into the distance. The Ponzo illusion involves placing two lines over an illustration of a railroad track. Which line is longer? In reality, they are exactly the same length. 5 The Zollner Illusion Fibonacci / Wikimedia Commons Sometimes the background of an image can interfere with how your brain interprets the image itself, as is the case with the Zollner illusion. This is one illusion that can actually make a viewer start to feel slightly queasy if you stare at it for too long! 6 The Kanizsa Triangle Illusion Wikimedia Commons According to the Gestalt law of closure, we tend to see objects that are close together as a related group. In the case of the Kanizsa Triangle, we even see contour lines that don't exist and ignore gaps in order to form a cohesive image. 7 The Muller-Lyer Illusion Fibonacci / Wikimedia Commons Here's a classic illusion that still manages to stump a lot of people. Which line is longer? Actually, both lines are the same length. Surprised? Find out about how the Muller-Lyer Illusion works. 8 The Moon Illusion If you've ever spent any time gazing up at the night sky, then you've probably noticed the moon illusion, in which the moon looks bigger on the horizon than it does higher up in the sky. Why does this happen? Many theories have been proposed, although there is no universally agreed-upon explanation. You can read about how the moon illusion works and some of the possible theories that have been suggested. 9 The Lilac Chaser Illusion TotoBaggins / Wikimedia Commons In the lilac chaser illusion, the viewer observes several different visual effects over the span of about 30 seconds. First described in 2005, the illusion is caused by a number of different factors including negative afterimages and what is known as Troxler fading. Check out the illusion yourself and learn more about how the lilac illusion works. 10 The Negative Photo Illusion geloo, modified by Kendra Cherry Here is another fun example of negative afterimages that produce a startling result. In the negative photo illusion, your brain and visual system essentially take a negative image and turn it into a full-color photo. Check out the illusion to give it a try and learn more about how it works. 9 Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Ross Lab, University of Pittsburgh. Making sense of the Hermann Grid illusion. Song S, Liu Y, Zhang J. Decoding the subjective rotation direction of the spinning dancer from fMRI data. Proceedings. 2015;94171. doi:10.1117/12.2081570 Qian L, Liu S, Lei Q. Illusory distance modulates perceived size of afterimage despite the disappearance of depth cues. PLOS ONE. 2016;11(7):e0159228. doi:10.1371/journal.pone.0159228 Kreiner WA. Algebraic functions describing the Zöllner illusion. Open Access Repositorium der Universität Ulm. 2012. doi:10.18725/OPARU-2597 Wagemans J, Elder JH, Kubovy M, et al. A century of Gestalt psychology in visual perception: I. Perceptual grouping and figure-ground organization. Psychol Bull. 2012;138(6):1172–1217. doi:10.1037/a0029333 Weidner R, Boers F, Mathiak K, Dammers J, Fink R. The temporal dynamics of the Müller-Lyer illusion. Cerebral Cortex. 2010;20(7):1586-1595. doi:10.1093/cercor/bhp217 Weidner R, Plewan T, Chen Q, Buchner A. The moon illusion and size-distance scaling - evidence for shared neural patterns. Journal of Cognitive Neuroscience. 2014;26(8):1871-1882. doi:10.1162/jocn_a_00590 Bertamini, M. Lilac chaser illusion. In: Programming Visual Illusions for Everyone. Vol 2. Springer International Publishing; 2017: 153-161. Powell G, Bompas A, Sumner P. Making the incredible credible: afterimages are modulated by contextual edges more than real stimuli. J Vis. 2012;12(10). doi:10.1167/12.10.17 Editorial Process Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit