Optical illusion in the context of "Op art"

Persistence of vision is the optical illusion that occurs when the visual perception of an object does not cease for some time after the rays of light proceeding from it have ceased to enter the eye. The illusion has also been described as "retinal persistence", "persistence of impressions", simply "persistence" and other variations. A very commonly given example of the phenomenon is the apparent fiery trail of a glowing coal or burning stick while it is whirled around in the dark.

Many explanations of the illusion seem to describe positive afterimages or smear (comparable to motion blur in photography, film and video).

The term beta movement is used for the optical illusion of apparent motion in which the very short projection of one figure and a subsequent very short projection of a more or less similar figure in a neighbouring location are experienced as one figure moving.

The illusion of motion caused by animation and film is sometimes believed to rely on beta movement, as an alternative to the older explanation known as persistence of vision. However, the human visual system can't distinguish between the short-range apparent motion of film and real motion (where the successive positions of figures in successive impressions largely overlap), while the long-range apparent motion of beta movement is recognised as different and processed in a different way.

The Necker cube is an optical illusion that was first published as a rhomboid in 1832 by Swiss crystallographer Louis Albert Necker. It is a simple wire-frame, two dimensional drawing of a cube with no visual cues as to its orientation, so it can be interpreted to have either the lower-left or the upper-right square as its front side.

Attribute substitution is a psychological process thought to underlie a number of cognitive biases and perceptual illusions. It occurs when an individual has to make a judgment (of a target attribute) that is computationally complex, and instead substitutes a more easily calculated heuristic attribute. This substitution is thought of as taking place in the automatic intuitive judgment system, rather than the more self-aware reflective system. Hence, when someone tries to answer a difficult question, they may actually answer a related but different question, without realizing that a substitution has taken place. This explains why individuals can be unaware of their own biases, and why biases persist even when the subject is made aware of them. It also explains why human judgments often fail to show regression toward the mean.

The theory of attribute substitution unifies a number of separate explanations of reasoning errors in terms of cognitive heuristics. In turn, the theory is subsumed by an effort-reduction framework proposed by Anuj K. Shah and Daniel M. Oppenheimer, which states that people use a variety of techniques to reduce the effort of making decisions.

An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people.

Illusions may occur with any of the human senses, but visual illusions (optical illusions) are the best-known and understood. The emphasis on visual illusions occurs because vision often dominates the other senses. For example, individuals watching a ventriloquist will perceive the voice as coming from the dummy since they are able to see the dummy mouth the words.

The Crooked House was a pub in South Staffordshire, England. Its name and distinctive appearance were the result of 19th-century mining subsidence which caused one side of the building to be approximately 4 feet (1.2 m) lower than the other. It was known as "Britain's wonkiest pub", and optical illusions inside the building made objects appear to roll uphill.

Located in Himley in England's Black Country, the building was originally an 18th-century millhouse before it was converted into a pub in the 1830s. In July 2023, the pub closed and was sold. The following month, the building was gutted in a fire and the new owners demolished it against the instructions of South Staffordshire Council. Criminal charges of arson with intent to endanger life have been brought against multiple people, and the landowner has been issued with an enforcement notice which requires them to reconstruct the building. The landowner lodged an appeal against the order, and their offer to relocate the pub has been opposed by campaigners.

Trompe-l'œil (French for 'deceive the eye'; /trɒmpˈlɔɪ/ tromp-LOY; French: [tʁɔ̃p lœj] ) is an artistic term for the highly realistic optical illusion of three-dimensional space and objects on a two-dimensional surface. Trompe-l'œil, which is most often associated with painting, tricks the viewer into perceiving painted objects or spaces as real. Forced perspective is a related illusion in architecture, and Op art a modern style mostly dealing with geometric patterns.

Forced perspective is a technique that employs optical illusion to make an object appear farther away, closer, larger or smaller than it actually is. It manipulates human visual perception through the use of scaled objects and the correlation between them and the vantage point of the spectator or camera. It has uses in photography, filmmaking and architecture.

The term illusory motion, or motion illusion or apparent motion, refers to any optical illusion in which a static image appears to be moving due to the cognitive effects of interacting color contrasts, object shapes, and position. The stroboscopic animation effect is the most common type of illusory motion and is perceived when images are displayed in fast succession, as occurs in movies. The concept of illusory motion was allegedly first described by Aristotle.

Louis Albert Necker de Saussure FRSE MWS FGS (10 April 1786 – 20 November 1861) was a Swiss crystallographer and geographer.

He is best remembered for devising the optical illusion now known as the Necker cube.

Edgar John Rubin (September 6, 1886 – May 3, 1951) was a Danish psychologist/phenomenologist, remembered for his work on figure-ground perception as seen in such optical illusions like the Rubin vase.

Born to Jewish parents, Rubin was born and raised in Copenhagen. Enrolling at the University of Copenhagen in 1904, he majored in psychology and finished his magister artium examination in philosophy in 1910.

The checker shadow illusion is an optical illusion published by Edward H. Adelson, professor of vision science at MIT, in 1995. It demonstrates the context-dependent nature of human color perception.

The antisolar point is the abstract point on the celestial sphere directly opposite the Sun from an observer's perspective. This means that the antisolar point lies above the horizon when the Sun is below it, and vice versa. On a sunny day, the antisolar point can be easily found; it is located within the shadow of the observer's head. Like the zenith and nadir, the antisolar point is not fixed in three-dimensional space, but is defined relative to the observer. Each observer has an antisolar point that moves as the observer changes position.

The antisolar point forms the geometric center of several optical phenomena, including subhorizon haloes, rainbows, glories, the Brocken spectre, and heiligenschein. Occasionally, around sunset or sunrise, anticrepuscular rays appear to converge toward the antisolar point near the horizon. However, this is an optical illusion caused by perspective; in reality, the "rays" (i.e. bands of shadow) run near-parallel to each other.

Louis-Léopold Boilly (French pronunciation: [lwi leɔpɔl(d) bwɑji] ; 5 July 1761 – 4 January 1845) was a French painter and draftsman. A creator of popular portrait paintings, he also produced a vast number of genre paintings documenting French middle-class social life. His life and work spanned the eras of monarchical France, the French Revolution, the Napoleonic Empire, the Bourbon Restoration and the July Monarchy. His 1800 painting Un Trompe-l'œil introduced the term trompe-l'œil ("trick the eye"), applied to the technique that uses realistic imagery to create the optical illusion that the depicted objects exist in three dimensions, though the "unnamed" technique itself had existed in Greek and Roman times.

Peter Mark Roget LRCP FRS FRCP FGS FRAS (UK: /ˈrɒʒeɪ/ US: /roʊˈʒeɪ/; 18 January 1779 – 12 September 1869) was a British physician, natural theologian, lexicographer, and founding secretary of The Portico Library. He is best known for publishing, in 1852, the Thesaurus of English Words and Phrases, a classified collection of related words (thesaurus). In 1824, he read a paper to the Royal Society about a peculiar optical illusion which is often (falsely) regarded as the origin of the ancient persistence of vision theory that was later commonly, yet incorrectly, used to explain apparent motion in film and animation.

Mach bands is an optical illusion named after the physicist Ernst Mach. It exaggerates the contrast between edges of the slightly differing shades of gray, as soon as they contact one another, by triggering edge-detection in the human visual system. The Mach band illusion is sometimes called the Chevreul illusion.

The Müller-Lyer illusion is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they tend to place it more towards the "tail" end. The illusion was devised by Franz Carl Müller-Lyer (1857–1916), a German sociologist, in 1889.

Research suggests all humans are susceptible to the illusion across cultures.