Perceptions of relative sizes. The most known version This illusion consists of two circles, identical in size, being placed side by side, with circles around one of them. big size, while the other is surrounded by small circles; in this case, the first circle seems smaller than the second.

The illusion is named after the German psychologist Hermann Ebbinghaus (1850-1909) who discovered it. IN English-speaking environment it became popular thanks to the textbook published in 1901 experimental psychology Titchener; This is where another name for illusion comes from - "Titchener circles" .

Although it is generally believed that this optical illusion is related to perception sizes, recently an opinion has emerged that the critical factor in the occurrence of this illusion is the distance of the central circle from the other circles surrounding it, and the closedness of the ring, which makes it possible to consider the Ebbinghaus illusion as a type of Delboeuf illusion. If the surrounding circles are close to the center circle, it appears larger, and conversely, if they are farther apart, the center circle appears smaller. Apparently, the size of the outer circles determines how close they can be to the center circle, leading to confusion between the two measures (size and distance) in many studies.

The Ebbinghaus illusion plays key role in modern scientific debates about the existence in the visual cortex of two separate streams of information processing related to the processes of perception (recognition) and execution of actions ( for more details see: Hypothesis about two streams of visual information processing ). The Ebbinghaus illusion has been proven to distort perception size, but when the subject must respond to visual image action, such as grasping, the dimensions of an object are perceived without distortion. However, a relatively recent publication has appeared claiming that the original experiments were carried out with large errors. In these experiments, the stimuli limited the possibility of error in the act of grasping, thereby making the grasping response more accurate. In addition, two versions of the stimulus - visually large and small - were presented in isolation (that is, there was no second central circle serving for comparison), due to which, according to V. Franz et al., results were obtained that indicate absence of illusion. The authors of the mentioned publication conclude that the Ebbinghaus illusion introduces distortions, regardless of the specific channel (path) of processing visual information (« recognition" or " action»).

In another modern work it is argued that susceptibility to this illusion, as well as the Ponzo illusion, is positively influenced by the size of the primary visual cortex of a particular individual.

In animals

There is information that some species of birds (chickens, pigeons, muslins, gray parrots) are susceptible to the Ebbinghaus illusion (as well as some others).

see also

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Notes

Excerpt characterizing the Ebbinghaus illusion

The Emperor lowered his ear, frowning slightly to indicate that he had not heard.
“I’m waiting, your Majesty,” Kutuzov repeated (Prince Andrei noticed that Kutuzov’s upper lip, while he was saying this I'm waiting). “Not all the columns have assembled yet, Your Majesty.”
The Emperor heard, but apparently did not like this answer; he shrugged his stooped shoulders and glanced at Novosiltsev, who stood nearby, as if with this glance he was complaining about Kutuzov.
“After all, we are not in Tsaritsyn Meadow, Mikhail Larionovich, where the parade does not begin until all the regiments arrive,” said the sovereign, again looking into the eyes of Emperor Franz, as if inviting him, if not to take part, then to listen to what he speaks; but Emperor Franz, continuing to look around, did not listen.
“That’s why I’m not starting, sir,” Kutuzov said in a sonorous voice, as if warning against the possibility of not being heard, and something trembled in his face once again. “That’s why I’m not starting, sir, because we’re not at the parade or in Tsarina’s meadow,” he said clearly and distinctly.
In the sovereign's retinue, all the faces, instantly exchanging glances at each other, expressed murmur and reproach. “No matter how old he is, he should not, in no way should speak like that,” these persons expressed.
The Emperor looked intently and carefully into Kutuzov's eyes, waiting to see if he would say anything else. But Kutuzov, for his part, bowing his head respectfully, also seemed to be waiting. The silence lasted for about a minute.
“However, if you order, Your Majesty,” said Kutuzov, raising his head and again changing his tone to the previous tone of a stupid, unreasoning, but obedient general.
He started his horse and, calling the head of the column, Miloradovich, gave him the order to attack.
The army began to move again, and two battalions of the Novgorod regiment and a battalion of the Absheron regiment moved forward past the sovereign.
While this Absheron battalion was passing, the ruddy Miloradovich, without an overcoat, in a uniform and orders and with a hat with a huge plume, worn on one side and from the field, the march march jumped forward and, with a valiant salute, reined in the horse in front of the sovereign.
“With God, general,” the sovereign told him.
“Ma foi, sire, nous ferons ce que qui sera dans notre possibilite, sire, [Really, Your Majesty, we will do what we can do, Your Majesty,” he answered cheerfully, nevertheless causing a mocking smile from the gentlemen the sovereign's retinue with his bad French accent.
Miloradovich turned his horse sharply and stood somewhat behind the sovereign. The Absheronians, excited by the presence of the sovereign, with a valiant, brisk step, kicking their feet, passed by the emperors and their retinue.
- Guys! - Miloradovich shouted in a loud, self-confident and cheerful voice, apparently so excited by the sounds of shooting, the anticipation of battle and the sight of the brave Absheronians, even his Suvorov comrades, briskly passing by the emperors that he forgot about the presence of the sovereign. - Guys, this is not your first village to take! - he shouted.
- Glad to try! - the soldiers shouted.
The sovereign's horse shied away from an unexpected cry. This horse, which had already carried the sovereign at shows in Russia, here, on the Champs of Austerlitz, carried its rider, withstanding his scattered blows with his left leg, pricking up his ears at the sounds of gunshots, just as he did on the Champ de Mars, not understanding the meaning of either these heard shots, not the proximity of the black stallion of Emperor Franz, not everything that was said, thought, felt that day by the one who rode her.
The Emperor turned to one of his entourage with a smile, pointing to the fellows of Absheron, and said something to him.

Kutuzov, accompanied by his adjutants, rode at a pace behind the carabinieri.
Having traveled half a mile at the tail of the column, he stopped at a lonely abandoned house (probably a former inn) near the fork of two roads. Both roads went downhill, and troops marched along both.
The fog began to disperse, and vaguely, about two miles away, enemy troops were already visible on opposite hills. To the left below the shooting became louder. Kutuzov stopped talking with the Austrian general. Prince Andrei, standing somewhat behind, peered at them and, wanting to ask the adjutant for a telescope, turned to him.

Don't Believe Your Eyes: A Guide to optical illusions

Don't Believe Your Eyes: A Guide to Optical Illusions

Try to imagine that the evolution of life on the planet took a different path and animals (including you and me) were unable to acquire such a sense as vision. Does not work? No wonder - we are so used to relying on our eyes that we cannot even imagine what it would be like the world without optical component. Despite the importance of vision, it is not so perfect - for example, some combinations of signals can “outsmart” the brain (as we know, we “see” with neurons, not with our eyes), forcing a person to get confused about the size of objects or guess “movement” in a static image . Now, attention! Sit comfortably, “turn off” all senses except vision and focus on the screen - we will talk about optical illusions.

Classic optical illusions

The history of optical illusions goes back thousands of years; back in 350 BC, Aristotle wrote: “Our senses can be trusted, but they are still easy to deceive.” Great thinker noticed that if you look at a waterfall for a while, and then turn your gaze to a stationary mountain slope, the rocks may appear to be moving in the opposite direction of the flow. Modern researchers This optical phenomenon is called the motion aftereffect or the illusion of a waterfall.

When we watch the flow of water, some of the neurons in our brain adapt to the unidirectional movement of light signals, as a result, when looking after a waterfall at a static object, we continue to “see” movement for some time, only in the opposite direction.

Illusion of relative size perception

Ebbinghaus illusion

In the 19th century, active study of the properties of perception and the characteristics of the human sense organs began. It was then that researchers developed optical illusions that are now considered classic, primarily the Ebbinghaus illusion.

Even if you are not too interested in the history of psychology, it is probably familiar to you, take a look at the picture. You, of course, understand that the sizes of the orange circles are the same, since you have seen such illusions a thousand times, but your eyes still lie to you - for a split second you get the feeling that they are still different. The human brain determines the size of objects and images based on the size of adjacent objects and inevitably falls into the trap - against the background of large black circles, orange appears smaller than next to small circles.

Depth perception illusion

At the beginning of the 20th century, Italian psychologist Mario Ponzo was one of the first scientists to demonstrate to the world that the perception of the size of objects is influenced not only by adjacent objects, but also by the depth of the background. The Italian developed the classic illusion that now bears his name.

The Ponzo illusion looks very simple - between two inclined lines there are two identical horizontal ones, while one of them is perceived as longer. Slanted lines create perspective, the brain believes that the upper horizontal line is located “further” than the lower one and makes an adjustment for the “distance” - due to this, a curious effect occurs.

"Magic" Müller-Lyer lines

Another textbook optical illusion, which is more than a hundred years old, is the Müller-Lyer illusion. Its essence is also quite simple - the figure shows lines with arrows at the ends; the one framed by the “tails” of the arrows seems larger.

Scientists are still arguing about the mechanism by which the illusion occurs; currently, the following interpretation is the most popular. The brain interprets three converging lines as part of a three-dimensional object, while the lines forming a “tip” are perceived as a closer object (say, the corner of a building when viewed from the outside). “Tail” arrows, in turn, create the illusion of a distant object (“room corner”). As with the Ponzo illusion, the brain “compensates for distance” to the object, causing the lines to appear different.

Helmholtz's riddle

Surprises are presented to the brain not only by converging lines, but also by parallel vertical or horizontal ones. At the end of the 19th century German physicist and the physiologist Hermann von Helmholtz showed that the lined horizontal lines the square looks wider and lower than exactly the same one, but made up of vertical lines.

The phenomenon discovered by Helmholtz is widely used in the production of clothing, however, contrary to popular misconception, horizontal stripes on sweaters and dresses do not “fatten”, but exactly the opposite - they visually make the figure narrower and taller. Glossy fashion magazines often contain advice like: “Wear clothes with vertical stripes to look slimmer,” but science mercilessly refutes this. Take a look at the Helmholtz illusion and see for yourself that the effect is exactly the opposite.

It is worth noting that this optical illusion has been studied far and wide, but scientists cannot yet come to a conclusion unanimous opinion about the mechanisms of its occurrence.

Classic early illusions turned people's ideas about the world around them upside down - as it turned out, you can't always “believe your eyes.” Nicholas Wead, a specialist in the history of optical illusions from the University of Dundee (Scotland), is confident that optical illusions have played a significant role in the study of the properties of perception: “By creating illusions, scientists realized that even understanding the mechanism of the eyes does not provide a holistic understanding of the nature of vision.” Wade notes that the pioneers of optical illusions attempted to combine them into one general theory, however, they were not successful. As it was later discovered, the human brain’s reactions to optical illusions are much more complex and varied than what researchers saw at the turn of the 19th and 20th centuries.

Illusions in the 20th century

In the “age of wars and revolutions,” humanity has witnessed many breakthroughs in ideas about the nature of optical illusions. Advances in science and technology have given specialists the opportunity to look at the problem differently. Let's say that the experiments of Thorsten Wiesel and David Hubel proved what kind of perception different zones different neurons are responsible for the visual field - for this discovery, researchers in 1981 were awarded Nobel Prize in medicine.

A little later than scientists, artists took up visual distortions - in the 1950s, a whole movement in art appeared dedicated to optical illusions, it was called op art (from the English optical art - “optical art”). The French artist and sculptor Victor Vasarely is considered one of the founders of op art; his works are often cited as bright examples optical illusions.

Illusions of our time

At the beginning of the 21st century, interest in visual distortions continues to grow - new scientific theories, with the help of which scientists are trying to explain the mechanisms of optical illusions. According to one of them, distortions occur due to the fact that human brain constantly “predicts” the image to compensate for the delay between the event itself and the moment of its perception. For example, while you are reading this article, your brain is processing light signals coming from a computer monitor or gadget screen. This requires certain time, so in a way you are not seeing the present, but the past.

Neuroscientist Mark Changizi believes that the brain's attempts to "anticipate" a picture explain some visual distortions.

Experiments by Changizi and his colleagues from the Californian Institute of Technology show that this theory is not contradicted by any of the classical optical illusions. Among the most illustrative examples“predictions” of images by the brain Changizi calls the famous Hering illusion. When a person moves forward, the objects he sees move along radial lines, so the brain tends to perceive such images as a sign of movement in space. “These mechanisms work great in real life, but they also force the brain to make mistakes when a person sees radial lines and at the same time remains in place,” notes the researcher.

Necker cube and other “whims” of the brain

The invention of magnetic resonance imaging was a real gift for researchers of optical illusions - science was finally able to at least general outline understand what happens in the human brain when they are perceived. Thus, by studying the brain activity of a person looking at a Necker cube, scientists concluded that the brain ambiguously perceives the depth of the image. The neurons seem to be “arguing” among themselves which picture should be considered “true”, as a result the observer sees the cube in one position or another.

The situation is similar with another well-known optical illusion - the so-called Herman grid. Take a look at the image - with your peripheral vision you “see” gray dots at the intersection of white lines, but as soon as you focus your gaze on one “gray dot”, it immediately “disappears”. According to one of the most popular explanations for this phenomenon among scientists, there is a continuous “struggle” among neurons to process dark and light areas of the image, which causes a person to “notice” flickering dots.

The latest ideas about illusions

Thanks to modern methods research, humanity knows that the perception of shades of color, shapes of objects and their movement in space are responsible different areas brain, but how we get a holistic image remains largely a mystery. Enthusiasts are developing more and more new ways to deceive the eye, reinterpreting and complementing classic illusions. By looking at them, we diligently “allow” our own brain to mislead us, and as a result, more questions arise than answers.

Nowadays, interest in the problem is so high that for the past ten years, experts have annually held a competition for the best optical illusion. For example, in 2014 this award was given to the dynamic Ebbinghaus illusion, which deceives the eye much more convincingly than the classic static version. According to neurologist Suzanne Martinez-Conde, who is part of the competition jury, due to constant change size of adjacent objects, the effect of the new illusion is several times stronger than that of a still image proposed by Hermann Ebbinghaus.

Martinez-Conde admits that most of Modern research into optical illusions builds on the work done by 19th-century scientists. For example, Hermann Helmholtz was the first to understand that human eyes constantly make rapid coordinated movements, so-called saccades. To understand what we are talking about, close one eye and lightly press your finger on the lower eyelid of the other - the “picture” that your brain sees will immediately begin to move. In ordinary life, we do not notice these microscopic “twitches”, because the brain has long ago learned to smooth out the image, but when it is faced with an unusual situation ( mechanical impact on the eyeball), saccades manifest themselves in all their glory.

According to Suzanne, it is saccades that play a key role in the famous “Rotating Snakes” illusion, which was developed by the Japanese psychiatrist Akioshi Kitaoka. In experiments with Snakes, Martinez-Conde and her colleagues found that when looking at the illusion, the same neurons are activated as when looking out of the window of a fast-moving train, when the landscape seems to be “passing by”, rather than vice versa. Moreover, if, with the help of some tricks, the observer is forced to stop saccades, the illusion disappears.

Ebbinghaus illusion or Titchener circle- an optical illusion of perception of relative sizes. The most famous version of this illusion is that when two circles of identical size are placed side by side, with one surrounded by large circles while the other is surrounded by small circles, the first circle appears smaller than the second.

History and interpretations

The illusion is named after the German psychologist Hermann Ebbinghaus (1850-1909), who first described this phenomenon. In the English-speaking environment, it became popular thanks to Titchener’s textbook of experimental psychology, published in 1901, hence another name for illusion - "Titchener circles".

It is generally believed that this optical illusion is related to the perception sizes, However, recently the idea has appeared that the critical factor in the occurrence of this illusion is the distance of the central circle from other chains surrounding it, and the closedness of the ring, allows us to consider the Ebbinghaus illusion as a type of Delboeuf illusion. If the surrounding circles are close to the center circle, it appears large, and conversely, if they are far apart, the center circle appears smaller. Apparently, the size of the described circles serves as a guide to how close they can be to the central circle, leading to confusion in many studies between the two indicators (size and distance).

The Ebbinghaus illusion plays a key role in contemporary scientific debate about the existence of two separate streams of information in the visual cortex concerning the processes of perception (recognition) and execution of actions. The Ebbinghaus illusion has been shown to distort the perception of size, but when the subject must respond to a visual image with an action such as grasping, the object's size is perceived without distortion. However, relatively recently a publication has appeared claiming that the original experiments were carried out with large errors. In these experiments, the stimuli limited the possibility of error in the act of grasping, which made the “grasping” response accurate. In addition, two versions of the stimulus - visually large and small - arose in isolation (that is, there was no second central circle that would serve for comparison), therefore, according to V. Franz et al., results were obtained that indicate the absence illusions. The authors of the mentioned publication conclude that the Ebbinghaus illusion introduces distortions, regardless of the specific channel (path) of processing visual information (“recognition” or “action”).

In a different modern research it is argued that susceptibility to this illusion, as well as the Ponzi illusion, is positively influenced by the size of the primary visual cortex of a particular individual.

In animals

There is evidence that some species of birds (chickens, pigeons, porcupines, gray parrots) are prone to the Ebbinghaus illusion (as well as a number of others).

Perceptions of relative sizes. The most famous version of this illusion is that two circles, identical in size, are placed side by side, with large circles around one of them, while the other is surrounded by small circles; in this case, the first circle seems smaller than the second.

The illusion is named after the German psychologist Hermann Ebbinghaus (1850-1909) who discovered it. In the English-speaking environment, it became popular thanks to Titchener’s textbook on experimental psychology, published in 1901; This is where another name for illusion comes from - "Titchener circles" .

Although it is generally believed that this optical illusion is related to perception sizes, recently an opinion has emerged that the critical factor in the occurrence of this illusion is the distance of the central circle from the other circles surrounding it, and the closedness of the ring, which makes it possible to consider the Ebbinghaus illusion as a type of Delboeuf illusion. If the surrounding circles are close to the center circle, it appears larger, and conversely, if they are farther apart, the center circle appears smaller. Apparently, the size of the outer circles determines how close they can be to the center circle, leading to confusion between the two measures (size and distance) in many studies.

The Ebbinghaus illusion plays a key role in modern scientific debate about the existence in the visual cortex of two separate streams of information processing related to the processes of perception (recognition) and execution of actions ( for more details, see: Hypothesis of two streams of visual information processing). The Ebbinghaus illusion has been proven to distort perception size, but when the subject must respond to a visual image action, such as grasping, the dimensions of an object are perceived without distortion. However, a relatively recent publication has appeared claiming that the original experiments were carried out with large errors. In these experiments, the stimuli limited the possibility of error in the act of grasping, thereby making the grasping response more accurate. In addition, two versions of the stimulus - visually large and small - were presented in isolation (that is, there was no second central circle serving for comparison), due to which, according to V. Franz et al., results were obtained that indicate absence of illusion. The authors of the mentioned publication conclude that the Ebbinghaus illusion introduces distortions, regardless of the specific channel (pathway) of processing visual information (“ recognition" or " action»).

Other recent work suggests that susceptibility to this illusion, as well as the Ponzo illusion, is positively influenced by the size of an individual's primary visual cortex.

In animals

There is information that some species of birds (chickens, pigeons, muslins, gray parrots) are susceptible to the Ebbinghaus illusion (as well as some others).

see also

• Delboeuf illusion

Notes

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Most of us are familiar with the phenomenon of optical illusions thanks to entertainment websites, popular science books and the works of artists, for example, the engravings of the famous Maurits Escher. But optical illusions can do more than just amaze - they help scientists better understand how our sensory perception the surrounding world correlates with the objective physical reality. The American organization Neural Correlate Society promotes such scientific research: every year she holds a competition where anyone can submit an optical illusion they have discovered with an illustration and a short description. T&P chose five winning illusions different years from those published on the competition website and described their action.

The mechanisms responsible for the occurrence of optical illusions are located in different parts nervous system human: from the retina to the visual cortex of the brain. The image that hits the retina contains a huge amount of information, and not all of it is transmitted to the brain. Let the numbers speak for themselves: the retina contains an average of 125 million photoreceptors and a hundred times less number of ganglion cells that generate nerve impulses. Our brains have to use abstract models to complete and piece together scattered pieces of incoming visual information. Sometimes he copes with this task too successfully: he creates a sense of integrity where there is none - in other words, he creates an optical illusion. Using the example of several of them, we will show exactly how our brain misleads us.

The illusion of "impossible movement"

The wooden balls in this video appear to be rolling up the slope as if they were being attracted by a magnet. Their behavior is inexplicable, as it contradicts the laws of physics. The image is not a 3D computer model, it’s just that the location of the gutters is perceived by the observer “in reverse” - in such a way that the downward movement of objects along them is mistaken for an upward one. It is noteworthy that the illusion created by Kokichi Sugihara from the Japanese Meiji Institute for Advanced Study of Mathematical Sciences, uses tangible three-dimensional objects and physical movement instead of a regular 2D image. IN in this case the deceptive effect is achieved by building a certain perspective: it is obvious that if we looked at this structure from any other angle, the illusion would not work. The material model of the Penrose triangle or “impossible triangle”, which was invented by young enthusiastic scientists, works according to the same laws. True, in order to be deceived, you will need to make an effort, because the illusion will work “correctly” only if you look at it from a certain point.

The "rotating mask" illusion

Whether we look at the convex or concave side of a mask, we cannot visually distinguish one from the other and will always perceive each as a face. As already mentioned, everything we see is the result of electrical signals transmitted from the eye to the brain along the optic nerve. It is the brain that processes these signals and constructs a specific image that our consciousness can perceive. Moreover, neuroscientists believe that there are certain areas in our brain that are responsible for recognizing faces. From our experience, we know that faces are convex, and the brain produces an image that corresponds to our expectations and established models. The habit is so strong that even the three-dimensional model of reality that is created by our stereoscopic vision is ignored. Interestingly, people suffering from schizophrenia cannot be deceived and are able to visually recognize the concave side of the mask. In their case, raw visual information is not “rewritten” by higher cognitive processes occurring in the brain. Some psychologists believe that such dysfunction in signal processing (when sensory perception dominates consciousness) increases the feeling of dissociation from reality in patients.

The Leaning Tower Illusion

Despite apparent simplicity, the effect of this illusion was first described in 2007 by scientists at Canada's McGill University. The two images of the Leaning Tower of Pisa are identical, but the observer has a strong feeling that the right tower is tilted more, as if it were photographed from a different angle. The fact is that adjacent photographs are perceived by us as one image. Typically, due to the laws of perspective taken into account by our visual system, the contours of two nearby towers tend to converge on the same point as they move away from the field of view. But if their contours are parallel, our brain assumes that the towers should diverge in different sides. The main discovery of scientists was the fact that our visual system interprets two identical images as a single landscape: no matter how hard we try to perceive them separately, we will always see the “Twin Towers of Pisa”, whose perspective can only be explained by the fact that the tilt of one there are many more of the towers.

Dynamic Ebbinghaus effect

The Ebbinghaus geometric illusion is possible due to our perception of the relationships between the sizes of objects. A person of average height will appear taller or shorter depending on whether he stands next to a professional basketball player or a hobbit. Likewise, the central circle will appear larger or smaller depending on the size of the objects surrounding it. This phenomenon can be explained in the following way: our perception adapts to a certain relationship between an object and its environment and extracts from it a certain criterion, which is then transferred to a new situation. For simplicity, this can be compared to the perception of sounds: if your laptop suddenly stops humming, you will instantly become aware of the silence in the room, although before that you may not have paid attention to the noise it made. IN classical illusion Ebbinghaus objects are static, but it turned out that the visual effect is significantly enhanced in dynamics: according to University scientists Nevada, to the authors of the illusion, the error in the perception of size almost doubles.

Multisensory "disappearing hand" illusion

Originally conceived by University of Nottingham scientists to simulate sensory loss in stroke patients, the illusion uses vision, touch and body position. The participant in the experiment does not notice how his perception of the position of his own hands gradually changes: after special manipulations programmed by scientists, the hands turn out to be much further from each other than it seems to the subject. When right hand disappears from the screen, he reaches for her with his left hand, but all he finds is empty table. The combination of loss of visibility and physical contact with his hand creates the complete illusion of its absence. Such experiments prove that perceptual errors can occur not only when viewing optical illusions - our entire apparatus of perception and interpretation of reality is greatly limited by abstract models developed by our brain during the process of evolution. We don’t know what reality actually looks and sounds like, we don’t know exactly what it feels like, we are easily misled, but it is through scientific research that we can get closer to the most complete perception of the world around us.

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