Penrose Staircase

The Penrose stairs, also known as the impossible staircase or the Penrose steps, is a visual illusion in the form of an impossible object created by the mathematician and physicist Roger Penrose.

The illusion is a two-dimensional representation of a staircase that appears to ascend or descend indefinitely, yet is physically impossible to climb or descend because the steps are not connected in a logical manner.

It is often used as an example of the type of optical illusion that can occur in the human brain and is used in cognitive psychology to study perception and attention.

Pensrose Staircase
The Penrose Staircase Illusion

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How does the Penrose Staircase Illusion work?

The Penrose stairs work by creating an illusion of a staircase that appears to be physically impossible.

The steps of the staircase are arranged in such a way that they appear to be connected, but in reality, they are not.

The human brain is fooled into perceiving the steps as being connected and therefore the illusion of a staircase that could be climbed or descended is created.

This illusion is created by using certain geometrical shapes such as rhombus and rectangles, which are arranged in a specific pattern.

The steps of the staircase are made up of two different types of rhombus shapes, one of which appears to be slanting upwards while the other appears to be slanting downwards.

This creates the illusion of a staircase that appears to be ascending or descending, while in reality, it is not possible to climb or descend the stairs.

The Penrose stairs have been used to study cognitive psychology and perception as it is a good example of how the human brain can be deceived by visual illusions, and also how we perceive and interpret visual information.

Versions of the Penrose Staircase Illusion

The following are some alternate versions of the Penrose Staircase Illusion:



From Wikimedia Commons



From Wikimedia Commons


Illusions like the Penrose Staircase Illusion

Paradox illusions are a type of optical illusion that involve images that appear to be self-contradictory or impossible. They typically involve the manipulation of visual cues such as size, shape, movement, and depth perception to create an image that appears to be impossible or defies our understanding of the physical world.

In general, these illusions work by exploiting the way the visual system processes information. The brain relies on certain cues, such as perspective, shading, and texture, to infer the 3D structure of an object. When these cues are manipulated in a certain way, the brain can be fooled into perceiving an impossible or self-contradictory image.

Some related illusions include the following:

The Penrose triangle, also known as the Penrose tribar, is an optical illusion that depicts a three-dimensional object that is physically impossible to construct.

Penrose Triangle

The Rubin vase, also known as the Rubin face or the figure-ground vase, is a famous optical illusion in which the image of a vase can also be perceived as two faces in profile looking at each other.

Rubin Vase Classic Black and White


The duck-rabbit illusion is an optical illusion that is an image that can be perceived as either a duck or a rabbit depending on how the viewer looks at it.

Duck Rabbit Illusion

The Necker cube is an optical illusion that features a simple wireframe drawing of a cube. The cube appears to switch back and forth between two different orientations.

Necker Cube

The My Wife and My Mother-in-Law illusion is an optical illusion with an image of a young woman’s face that can also be perceived as an older woman’s face.

Wife and Mother In Law

The Schröder Staircase is an optical illusion that features a drawing of a staircase. The staircase appears to be either ascending or descending, depending on how the brain interprets the angles of the lines.

Schroeders_stairs
From Wikimedia Commons

The impossible cube is an optical illusion that depicts a three-dimensional object that is physically impossible to construct.

Impossible Cube Illusion


The impossible trident is a three-pronged impossible shape resembling a trident. It is usually depicted as a three-pronged fork with each prong appearing to be a continuation of the next, creating an impossible shape.

Impossible Trident
From Wikimedia Commons

The spinning dancer illusion is a visual illusion that depicts a silhouette of a dancer spinning clockwise or counterclockwise. The direction of the dancer’s spin can appear to change depending on the viewer’s perception

Spinning Dancer Gif
From Wikimedia Commons

The Monroe-Einstein illusion works by playing with the viewer’s expectations about the relationships between the features of the faces and the viewer’s sense of facial proportions.

Monroe-Einstein

Discovery of the Penrose Staircase Illusion

It was first created by the British mathematician and physicist Roger Penrose and his father Lionel Penrose, a psychiatrist and mathematician, in the 1950s.

Sir Roger Penrose is a renowned British mathematical physicist and Nobel laureate. He was born in 1931 and is still active today. He is known for his work in the fields of cosmology, general relativity, and quantum mechanics. He was awarded the Nobel Prize in Physics in 2020, jointly with Reinhard Genzel and Andrea Ghez, for his contributions to the understanding of the properties of black holes.

Penrose’s research has focused on the fundamental nature of space and time and the structure of the universe, he proposed new ways of understanding the Big Bang, black holes, and the nature of the universe itself. He has also been interested in the connection between physics and mathematics, particularly in the area of geometry. Penrose has written several books on these topics, which have been widely read and discussed by both scientists and the general public.

Penrose is also known for his work on the concept of “cosmic censorship” which is a theory that states that the singularities that occur in black holes are always hidden from the outside observer. He also developed new mathematical techniques, such as the Penrose diagram, which are used to describe the behavior of black holes and other singularities. Penrose is considered one of the most influential theoretical physicist of the 20th century and his work has had a significant impact on our understanding of the universe.

References and Resources

Check out our complete list of illusions.

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