Shepard tables

The parallelograms of the Shepard tables are twisted, but identical.

Shepard tables are an optical illusion that Roger Shepard , a psychologist of Stanford University , in 1990 with the caption Tables Turn ( "Turning the Tables") in his book Mind Sights on the created by Him perceptual illusions published. It is a very effective optical illusion that usually misestimates the actual length by 20-25%.

Explanation

In A Dictionary of Psychology , the Shepard tables are described as a pair of identical parallelograms that represent the tabletops of two tables and appear distinctly different because our sense of sight decodes them using the rules for three-dimensional objects.

The optical illusion is based on a drawing of two parallograms that - apart from a rotation by 90 ° - are identical. When the parallelograms are recognized as table tops by adding table legs, we see them as objects in three-dimensional space. A table appears almost square because we consider one edge of the table to be shortened in perspective and the other long and narrow.

The MIT Encyclopedia of the Cognitive Sciences explains optical illusion as an effect of uniformity of size and shape that subjectively elongates the posterior length along the line of sight. She classifies the Shepard tables as an example of a geometric illusion in the "Illusion of Size" category.

Roger Shepard, the inventor of the illusion of perception by Shepard tables

According to Shepard, the knowledge we have about optical illusions and the understanding we gain on an intellectual level remain practically powerless to reduce the extent of the illusion.

Surprisingly, autistic children are less prone to the optical illusion when looking at the Shepard tables than their peers, although there is no difference in the Ebbinghaus illusion .

In 1981, Shepard described an earlier, less effective version of optical illusion as "parallelogram illusion." The optical illusion can also be created with identical trapezoids instead of identical parallograms.

A variant of the Shepard tables was chosen as Optical Illusion of the Year (“Best Illusion of the Year”) in 2009 .

Web links

Individual evidence

^ ^A ^b ^c Andrew M Colman: A Dictionary of Psychology , 3rd Edition, Oxford University Press ,, ISBN 9780191726828 : "The illusion was first presented by the US psychologist Roger N (ewland) Shepard (born 1929) in his book Mind Sights : Original Visual Illusions, Ambiguities, and Other Anomalies (1990, p. 48). Shepard commented that 'any knowledge or understanding of the illusion we may gain at the intellectual level remains virtually powerless to diminish the magnitude of the illusion' (p. 128). " And:" a pair of identical parallelograms representing the tops of two tables appear radically different "because our eyes decode them according to rules for three-dimensional objects.
^ ^A ^b Philippe Chouinard: The Psychology of Seeing in Autism . LaTrobe University. Retrieved on February 11, 2019: "[The Shepard tables] illusion is one of the strongest optical illusions that exists, on average the apparent size difference is 20-25%. Our preliminary work and earlier work performed by others (Mitchell, Mottron, Soulieres, & Ropar, 2010) reveal how susceptibility to this particular illusion is diminished considerably in persons with an ASD. "
↑ Christopher W Tyler: Paradoxical perception of surfaces in the Shepard tabletop illusion . In: I-Perception . 3, No. 3, May 19, 2011, pp. 137-141. doi : 10.1068 / i0422 . PMID 23145230 . PMC 3485780 (free full text). "One of the most profound visual illusions .. is the Shepard tabletop illusion, in which the perspective view of two identical parallelograms as tabletops at different orientations gives a completely different sense of the aspect ratio of the implied rectangles in the two cases (Shepard 1990 ). "
^ Arthur Gilman Shapiro, Dejan Todorovic: The Oxford Compendium of Visual Illusions . Oxford University Press, 2012, ISBN 978-0199794607 , p. 239: "For example, the famous Shepard tabletop illusion (Shepard, 1981) is more convincing when the planes are embedded in box shapes than when they are presented in isolation."
^ ^A ^b Robert Andrew Wilson, Frank C. Keil: The MIT Encyclopedia of the Cognitive Sciences . MIT Press, 2001, ISBN 978-0262731447 , pp. 385-386: "Size and shape constancy subjectively expand the near-far dimension along the line of sight to compensate for geometrical foreshortening."
^ RN Shepard: Mind Sights: Original visual illusions, ambiguities, and other anomalies, with a commentary on the play of mind in perception and art . WH Freeman and Company, 1990, ISBN 978-0716721345 , p. 128: "Because the inference about orientation, depth, and length are provided automatically by underlying neuronal machinery, any knowledge or understanding of the illusion we may gain at the intellectual level remains virtually powerless to diminish the magnitude of the illusion. "
↑ , K. Royals: Illusion Strength and Associated Eye Movements in Children with Autism Spectrum Disorder While Viewing Shepard and Ebbinghaus Illusion Displays . In: INSAR 2018 Annual Meeting. International Society for Autism Research.
↑ Susana Martinez-Conde, Stephen Macknik: Champions of Illusion: The Science Behind Mind-Boggling Images and Mystifying Brain Puzzles . Farrar, Straus and Giroux, 2017, ISBN 978-0374120405 , p. 46: "Photocopy this page and then ... cut around the trapezoid shapes ... The effect is a version of the classic Shepard Tabletop illusion."
^ David Phillips: Shepard's tables - What's up? . OpticalIllusion.net. October 14, 2009. Accessed February 10, 2019: "Recently Lydia Maniatis pointed out a puzzling aspect of the illusion, in her prize-winning entry for the Illusion of the Year Competition."
↑ Lydia Maniatis: Another turn: a variant on the Shepard tabletop illusion . In: Best Illusion of the Year Contest . 2009. Retrieved February 10, 2019: “The three pink- and blue-colored parallelograms are the same. All blue lines are equal in length; all pink lines are also equal. Box B is simply Box C rotated counterclockwise. But the three parallelograms look different, and boxes B and C look different. "

[OxfordDP-1] A ^b ^c Andrew M Colman: A Dictionary of Psychology , 3rd Edition, Oxford University Press ,, ISBN 9780191726828 : "The illusion was first presented by the US psychologist Roger N (ewland) Shepard (born 1929) in his book Mind Sights : Original Visual Illusions, Ambiguities, and Other Anomalies (1990, p. 48). Shepard commented that 'any knowledge or understanding of the illusion we may gain at the intellectual level remains virtually powerless to diminish the magnitude of the illusion' (p. 128). " And:" a pair of identical parallelograms representing the tops of two tables appear radically different "because our eyes decode them according to rules for three-dimensional objects.

[Latrobe-2] A ^b Philippe Chouinard: The Psychology of Seeing in Autism . LaTrobe University. Retrieved on February 11, 2019: "[The Shepard tables] illusion is one of the strongest optical illusions that exists, on average the apparent size difference is 20-25%. Our preliminary work and earlier work performed by others (Mitchell, Mottron, Soulieres, & Ropar, 2010) reveal how susceptibility to this particular illusion is diminished considerably in persons with an ASD. "

[Tyler-3] Christopher W Tyler: Paradoxical perception of surfaces in the Shepard tabletop illusion . In: I-Perception . 3, No. 3, May 19, 2011, pp. 137-141. doi : 10.1068 / i0422 . PMID 23145230 . PMC 3485780 (free full text). "One of the most profound visual illusions .. is the Shepard tabletop illusion, in which the perspective view of two identical parallelograms as tabletops at different orientations gives a completely different sense of the aspect ratio of the implied rectangles in the two cases (Shepard 1990 ). "

[OxfordC-4] Arthur Gilman Shapiro, Dejan Todorovic: The Oxford Compendium of Visual Illusions . Oxford University Press, 2012, ISBN 978-0199794607 , p. 239: "For example, the famous Shepard tabletop illusion (Shepard, 1981) is more convincing when the planes are embedded in box shapes than when they are presented in isolation."

[MIT-5] A ^b Robert Andrew Wilson, Frank C. Keil: The MIT Encyclopedia of the Cognitive Sciences . MIT Press, 2001, ISBN 978-0262731447 , pp. 385-386: "Size and shape constancy subjectively expand the near-far dimension along the line of sight to compensate for geometrical foreshortening."

[MindSights-6] RN Shepard: Mind Sights: Original visual illusions, ambiguities, and other anomalies, with a commentary on the play of mind in perception and art . WH Freeman and Company, 1990, ISBN 978-0716721345 , p. 128: "Because the inference about orientation, depth, and length are provided automatically by underlying neuronal machinery, any knowledge or understanding of the illusion we may gain at the intellectual level remains virtually powerless to diminish the magnitude of the illusion. "

[Autism-7] , K. Royals: Illusion Strength and Associated Eye Movements in Children with Autism Spectrum Disorder While Viewing Shepard and Ebbinghaus Illusion Displays . In: INSAR 2018 Annual Meeting. International Society for Autism Research.

[Trapezoid-8] Susana Martinez-Conde, Stephen Macknik: Champions of Illusion: The Science Behind Mind-Boggling Images and Mystifying Brain Puzzles . Farrar, Straus and Giroux, 2017, ISBN 978-0374120405 , p. 46: "Photocopy this page and then ... cut around the trapezoid shapes ... The effect is a version of the classic Shepard Tabletop illusion."

[animation-9] David Phillips: Shepard's tables - What's up? . OpticalIllusion.net. October 14, 2009. Accessed February 10, 2019: "Recently Lydia Maniatis pointed out a puzzling aspect of the illusion, in her prize-winning entry for the Illusion of the Year Competition."

[variant-10] Lydia Maniatis: Another turn: a variant on the Shepard tabletop illusion . In: Best Illusion of the Year Contest . 2009. Retrieved February 10, 2019: “The three pink- and blue-colored parallelograms are the same. All blue lines are equal in length; all pink lines are also equal. Box B is simply Box C rotated counterclockwise. But the three parallelograms look different, and boxes B and C look different. "